1
Committee 376
Concrete Structures for RLG Containment
Agenda ACI 376-C Analysis Sub-Committee Meeting,
Sunday, March 23, 2014, 3 PM – 5 PM
Grand Sierra Resort, Reno, NV
Room: N-12
1. CALL TO ORDER and APPROVAL OF AGENDA
2. INTRODUCTIONS
3. ANNOUNCEMENTS
4. DISCUSSION: TN on Design and Analysis of the TCP Embedment Zone Resolution of remaining negative votes and comments.
5. OTHER BUSINESS / INFORMAL DISCUSSION OF PROJECTS
6. ADJOURNMENT
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Technical Note on TCP (TCP – TN) Approved Sections Section Approved with Comments to be resolved Negative Vote 2013.04.13 376-C Minneapolis 2014.02.14 376-Webinar
Members that Voted Voting Members that did not vote 2013.04.13 – 376 D Minneapolis 2014.02.14 – 376 D Webinar
Voting Members that voted (79%) 1. Hjorteset, Kare 2. Brannan, Mike S 3. Allen, Junius 4. Ballard, Thomas A 5. Garrison,Jeffrey 6. Hatfield,Alan 7. Hoff, George C 8. Hoffmann, Richard A
9. Hoptay,Joseph 10. Howe, Thomas R 11. Jiang,Dajiu 12. Khalifa, Jameel U 13. Krstulovic-Opara, Neven 14. Legatos, Nicholas A 15. Malhotra,Praveen 16. Mash,Keith 17. Moncarz, Piotr D
18. Nussmeier, Robert W 19. Oliver, William H 20. Pawski, Rolf P 21. Rushing, William E 22. Wu,Sheng-Chi
Associate Members
Roetzer, Josef Widianto, Widianto
23. Hanskat, Charles S 24. Douglas,Hamish 25. Hashmi, Humayun 26. Rajan, Ramanujam S 27. Sward,Robert 28. Thompson,Eric
Members Attending: 1. Brannan, Mike 2. Hjorteset, Kare 3. Ballard, Thomas 4. Garrison. Jeffrey 5. Hoff, George 6. Hoptay, Joseph 7. Howe, Thomas 8. Khalifa, Jameel 9. Pawski, Rolf 10. Hanskat, Charles 11. Roetzer, Josef
Participating: 1. Allen, Junius 2. Brannan, Mike 3. Douglas, Hamish 4. Garrison. Jeffrey 5. Hjorteset, Kare 6. Hoptay, Joseph 7. Howe, Thomas 8. Jiang,Dajiu 9. Legatos, Nick 10. Krstulovic-Opara, Neven 11. Mash, Keith 12. Mehta, Sanjay 13. Oliver, Billy 14. Pawski, Rolf 15. Roetzer, Josef 16. Vossoughi, Fariborz
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
1
Brannan
I am not sure the TCP can be constructed as detailed because it would be impossible to weld both sides of the TCP plate to the embedment plate. It would also be better to radius the sharp corner shown on the TCP plate. Would it be possible to simply lap weld the TCP plate to the embedment plate? Should the embedment zone also extend 2X the wall thickness below the embedment plate?
The comment found partially persuasive. It is not intended that the TN covers TCP construction details. Furthermore, welding requirements should be as per API 620. Address the comment by revising text on page 1 lines 11-14: INTRODUCTION ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner Protection (TCP) embedment zone. The purpose of this Technical Note document is to provide further guidance for on (a) design and analysis of the TCP embedment anchorage detailing and (b) TCP liquid-tightness analysis (i.e., crack width calculations) in the TCP embedment zone (i.e., crack width calculations).
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Humayum, Howe, Wu, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with comment - Hoffman
With Respect to M. Brannan’s Comments, it is my opinion this can be welded from both sides, by making this attachment weld first and then going on with the construction. There will be a “fill-in plate that is required to build up the TCP side wall.
UPDATE NOTES (2013.01.08) a) 2013.10.21 Phoenix discussion items are on pg 14 of 15. b) See the following Ref. no. for NEGATIVES REQUIRING FURTHER DISCUSSION: 1, 18, 32, 37, 41, 44 & 47, 49, 63, 74. c) Pg. 16 of 16 has Legatos negative that requires further discussion. WEBINAR NOTES (2014.02.14) ~ no quorum a) Resolved Ref.No. 1, 32, 41, 44 & 47. Ref. No. 63 changed to editorial; RP to propose moving text. b) Ref. No. 18 and 49 to be discussed further in Reno. Ref. No. 37 and 74 need further discussion – missing notes of resolution.
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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1st Ballot Results (Approved w. Comment) 2nd Ballot Results
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Text Author Comments 2ND BALLOT:
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Suggested Change
Update title to read: Thermal Corner Protection Design & Crack Analysis Design and Analysis of the TCP Embedment Zone
I have no objection to the proposed changes
Disagree – Ballard
I believe the embedment zone should extend at least to the bottom of the TCP plate since migration of cracks in this zone would compromise the leak tightness of the detail.
2013.04.13 – 376-C Minneapolis: Agreed and that Tom Ballard to propose wording. From TB email dated 2013.04.15: “Although the code and this TN do not explicitly define leak tightness criteria for the anchorage and embeddment, the design and construction of these components should be carried out with the clear objective of protecting the corner joint from product temperatures.” 2014.02.14 Webinar Ballard wording ok
8 Page 5, line 2, item 3
Mash
Suggest rewording and removing 'substantially' link to definitive acceptance criterion to avoid confusion. Suggest exact acceptance criterion words such as - under the spillage condition the crack widths on the inside face shall be limited to xx, compressive stresses in both the meridional and vertical directions shall be minimum y, max z,
The comment found partially persuasive. Limiting values are covered in the Code (e.g., compressive zone size, crack width limits, etc.) and do not need to be repeated here. Revise text for clarity to read: “The concrete wall above the TCP, directly exposed to spilled product, should remain liquid and substantially vapor tight during the spill condition. This is assured by maintaining a compression zone in the wall exposed to the spill and by and limiting the crack width cracking on the inside face of the wall in the vicinity of the TCP embedment plate zone during a spill.”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with editorial changes – Khalifa, Roetzer, Krstulovic
“The concrete wall above the TCP, directly exposed to spilled product, should remain liquid tight and substantially vapor tight during the spill condition. 2013.04.13 – 376-C Minneapolis: Agree with comment.
10 Page 5 Line 10
Hoptay
The material selection is temperature dependent and to state that the TCP is 9% Ni infers an LNG tank and not RLG tanks in general.
The comment found persuasive. Change text to read: “Material selection and material requirements used in the
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum,
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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1st Ballot Results (Approved w. Comment) 2nd Ballot Results
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Suggested Change
design of the 9% nickel-steel TCP and secondary bottom plates may be performed in accordance with API 620.”
Howe, Wu, Ballard, Malhotra, Garrison, Mash, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic Disagree - Douglas This may still be ambiguous as API 620 does not refer to
TCP
2013.04.13 – 376-C Minneapolis: Change last line to read: “… should be in accordance with API 620.”
11 Page 5, line 4, item 6
Mash
Assurance is through cracks + compression zones not through cracks alone. Crack width limitation in the vicinity of the embed is to prevent liquid migration behind the TCP area.
No action. Covered in previous response.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
13 P. 5, Line 15
Wu
add “seismic Aftershock load”. The comment found persuasive. Change text to read:
“The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both (a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition including SSEAFT. The TCP design consists of the following steps:”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
15 Page 5, line 21, item 10
Mash
Starting temperatures and conditions should be selected so as to maximise the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby creating maximum straining across the section.
The comment found persuasive. Add proposed text to line 22: 1.2.1 – STEP 1: TCP Load Definition Finite element analyses is performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Legatos, Widianto, Hoptay, Roetzer, Hatfield, Krstulovic
2013.04.13 – 376-C Minneapolis: To address all comments, replace last three sentences with: “Initial temperatures and conditions should be selected to obtain the most severe design conditions. For instance the most severe condition for design of the anchors is likely to be a warm wall (summer) with a cold thermal shock to the embedment.”
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Text Author Comments 2ND BALLOT:
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Suggested Change
pressure, hydrostatic pressure and hydrodynamic pressure due to seismic aftershock. Starting temperatures and conditions should be selected so as to maximize the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby creating maximum straining across the section.
Agree with editorial changes - Hoff
For instance, for the design of the anchors, the critical condition is likely to be a warm wall (summer) and with a cold shocking to the embedment, thereby creating maximum straining across the section.
Agree with minor comment - Humayum
last sentence - straining or strain?
Agree with minor comment - Brannan
consider using “Design” instead of “Starting”.
Agree with editorial changes - Pawski
Starting temperatures and conditions should be selected so as to maximize the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking thermal shock to the embed. Whereby creating maximum straining across the section.
Agree with editorial changes - Douglas
Pawski 2013.04.23 – Allen comment below shown incorrectly as Douglas and deleted here. Correct comment is: "…....... cold shock to the embed which results in the maximum strain across the section " Douglas additional comment1 at end of Ballot Summary: "1. Page 5, Para 1.2.1 Line 24: Also Comment LE27: What is the advantage of the use of the term "demand" as opposed to load? If a new term is to be introduced then it's use must be defined: When is a load a demand?" Pawski 2013.04.23 – this is addressed by 376-C Minneapolis response above.
Agree with editorial changes - Allen
For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby Thereby creating maximum straining across the section.
Agree with changes - Oliver
Agree with suggested grammatical revision: Starting temperatures and conditions should be selected so as to maximize the resulting stresses in the component under consideration. For example for the design of the anchors, the critical condition is likely to be warm wall (summer) and cold shocking to the embed, creating maximum straining across the section. Comment: What does demand mean in this context? If not revised, add “demand” to definitions.
16 P. 5, Line 22, at the end of the paragraph
Wu
Add “and hydrodynamic pressure due to seismic aftershock”.
The comment found persuasive. Change text to read:
“Finite element analyses is performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the embedment
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Allen, Legatos,
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Suggested Change
will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, hydrostatic pressure and hydrodynamic pressure due to seismic aftershock (SSEAFT).”
Widianto, Hoptay, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with editorial change – Khalifa, Douglas, Roetzer, Krstulovic
“Finite element analyses is are performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall.
18 Page 5, line 28, item 12
Mash
Suggest inclusion of the words 'in the absence of a defined leak rate all intermediate levels shall be investigated. In practice this may be achieved by running a number spill levels to so as adequately bound the demands. Typically 5 levels may be used dividing the spill height into 4 equal units. In addition levels in close proximity to the TCP must be investigated.
Agree in principle with comment. Revise as noted and address spill levels in a future edition of the Code.
“Various spill levels should be considered to determine the most severe effect on the embedment and concrete wall. This should include a spill levels located just below the top of the TCP which will place the largest temperature differential between the TCP and the concrete wall. as well as various Also a minimum of three levels should be considered for spill levels above the TCP up to, at top of the TCP embedment zone, at mid-height, and full spill height. “
Agree – Jiang, Moncarz, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Allen, Legatos, Widianto, Roetzer, Hatfield, Brannan, Krstulovic
2013.04.13 – 376-C Minneapolis: Mash comment non-persuasive. Three is a minimum and does not preclude specifier from requiring or the designer choosing more.
Agree with suggested change -Khalifa
This should include a spill levels located just below the top of the TCP which will place generate the largest temperature differential between the TCP and the concrete wall.
Agree with editorial changes – Hoff, Pawski
This should include a spill levels located just below the top of the TCP which that will place the largest temperature differential between the TCP and the concrete wall Also A minimum of three levels should be considered for spill levels above the TCP up to,1) at top of the TCP embedment zone, 2) at mid-height, and 3) at full spill height.
Agree with editorial changes - Douglas
This should include a spill levels located just below the top of the TCP which will place result in the largest temperature differential between the TCP and the concrete wall
Agree with editorial changes - Hoptay
“…at the top of the TCP embedment zone, at mid-height, and full spill height”
Agree with editorial comment - Oliver
Change “place” to “produce”. Observation: The proposed text requires four levels, not so far from five.
Disagree - Mash Statement of 3 levels does not reflect the significance of the analysis. This is the most important analysis carried out for the outer tank and it is essential that an appropriate amount of levels be considered. Suggest that the text is amended to the following: Also a minimum of three five levels should be considered 2014.02.14 Webinar Discuss in Reno the issue of safety. Mash insists 5 minimum is a good starting point and contractor must demonstrate they have identified critical
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Suggested Change
condition.
20 Page 5, line32, item 14
Mash
Must be achieved through mechanical anchoring! The comment found persuasive. Revise to read: “The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall or by other suitable means (e.g., ???). Anchor bolts (studs) should be placed in continuous (circumferential) rows along the concrete wall.”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with suggested change -Khalifa, Roetzer
Delete second sentence completely as the same is essentially said in the next sentence. “The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall. Anchor studs should be placed in continuous (circumferential) rows along the concrete wall.” 2013.04.13 – 376-C Minneapolis: After discussion it was agreed delete second sentence as suggested.
Agree with suggested change -Garrison
Modify last sentence: “Anchor studs should be welded in continuous circumferential rows along the embed plate.”
2013.04.13 – 376-C Minneapolis: Withdrawn after discussion on deleting second sentence as per Khalifa, Roetzer, and Hoptay.
Disagree -Hoptay Delete second sentence because next sentence covers the same information
2013.04.13 – 376-C Minneapolis: After discussion it was agreed delete second sentence as suggested.
21 Page 6, line 1, item 1
Mash
When? Embedment must be anchored with studs? The comment found persuasive. Revise to read as noted below. Address questions on spacing and gap size in future: “When the The embedment plate isshould be anchored with
circumferential studs, a minimum of two rows of circumferential studs should be used to anchor the embedment plate. The spacing between mechanical anchors (studs) has significant impact on the TCP emebedment
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto,
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Text Author Comments 2ND BALLOT:
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Suggested Change
performance and thus should be considered in the design. should be limited to ensure that the axial, bending and shear stresses in the embedment plate are within the allowable stresses.”
Hoptay, Roetzer, Oliver, Hatfield, Krstulovic
Agree with comments -Pawski
Bullet points 1 & 2 should be combined Use “studs” or “bolt studs” consistently
Agree - Brannan Note that our Figure 1.1a shows four rows of circumferential studs. Should it show two rows of studs in solid line ink and the other two in shaded or dashed ink to indicate the potential for using more than two rows? 2013.04.13 – 376-C Minneapolis: Agree, annotate sketch to state “2-rows minimum.”.
Agree with editorial changes - Khalifa
Also recommend deleting bolts from first line under section 1.2.3
2013.04.13 – 376-C Minneapolis: “Anchors” to be used throughout. Edit TN and replace bolts & studs with “anchors.”
Disagree - Hoptay Disagree – studs are not always used for consistency suggest the following rewording The embedment plate should be anchored with a minimum of two circumferential rows of anchors. The spacing between anchors has significant impact on the TCP embedment performance and thus should be considered in the design. 2013.04.13 – 376-C Minneapolis: Persuasive, use proposed wording.
26 Page 6, line 19, item 4
Mash
Nothing mentioned regarding detailing? Suggest inclusion of words such as. Ideally crack control is best achieved through the introduction of smaller bars at closer spacings as opposed to larger bars at wider spacings. In this regard it is suggested that the bar spacing be selected so as to enable the subsequent introduction of lacer bars to the system. Therefore adoption of bar spacings of between 150 and 200mm is recommended in the vicinity of the TCP whereby allowing additional bars top be slotted in. Anchor spacings should be selected to as to be multiples of the bar spacing to enable a clash free design.
The comment found non-persuasive regarding suggested inclusion of bar detailing because this is normal everyday concrete detailing. Add the following after line 7 on page 6. “Anchor spacings should be selected to as to be multiples
of the bar spacing to enable a clash free design. “ Delete lines 6 and 7 on page 6. “Allowable stresses i.e., material selection and material
requirements used in the design of the embedment plates, may be selected in accordance with API 620.”
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Hoff, Hoptay, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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Suggested Change
NEW Page 6 Para 1.2.4
This comment inserted by Pawski 2013.04.23 Douglas additional comment 2 at end of Ballot Summary: The liquid tightness criteria are specified in Para 2.1, items 1 & 2. Additional tightness criteria on “embedment plates” should not require to be defined by owner. I am not in favour of definitions to be provided by owners. The statement is vague and ultimately provides no guidance.The code is to provide guidance to all, including owners.
Douglas
28 Page 7, line 1 4, item 1
Mash
Suggest using nomenclature such as demand as opposed to load.
The comment found persuasive in part. Revise to read. “When subjected to During the spill condition, the concrete wall will be loaded with subjected to high forces due to mechanical loads and thermal effects and mechanical forces. These forces that will lead to significant wall cracking. During the spill condition, integrity Integrity of the concrete wall must be maintained. As specified in the ACI 376 Code, the wall should remain liquid and substantially vapor tight. More specifically:”
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with editorial changes - Hoff, Krstulovic
During the spill condition, the concrete wall will be subjected to high forces due to mechanical loads and thermal effects that will can lead to significant wall cracking. 2013.04.13 – 376-C Minneapolis: Discussed and agree with comment.
Disagree - Hoptay Suggest rewording sentence as follows to cover both the transient and steady state condition. The integrity of the concrete wall must be maintained during the entire spill. 2013.04.13 – 376-C Minneapolis: Withdrawn.
32 Page 7, line 20, item 6
Mash
EN only calculates characteristic widths. Historically US codes have cocooned the crack width requirements into the detailing rules, These were based on the Gergely Lutz expressions which used mean widths. Replace 'as per' with 'in accordance with'
The comment found persuasive. Revise page 7 lines 20-21 to read. “3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean calculated crack widths. as per EN 1992-1-1.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Ballard, Malhotra, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2013.04.13 – 376-C Minneapolis: Agree with Wu. NEW BUSINESS for CODE - JG write the new business item on code change form Q1.
Disagree - Wu Suggest that: a) EN 1992-1-1 should stay, as stated in ACI 376 to delete “as characteristic and not mean”
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2013.04.13 – 376-C Minneapolis: Persuasive since crack widths calculated by EN 1992-1-1 will be characteristic. Proposed wording to be adopted.
Disagree - Garrison b) Committee needs to review the ability of the contractor / designer to meet the requirement of 0.008” max crack width using EN equations for the spill condition (2 cryogenic temperatures). Experience shows that this is a difficult requirement to meet. Instead, perhaps ACI 376 should specify minimum rebar size and spacing within the TCP embedment zone.
2013.04.13 – 376-C Minneapolis: Withdrawn pending future action by main committee. Jeff Garrison to prepare New Business (code change form Q1) proposal to address crack width values and method of calculation.
Disagree - Mash By removing the design code there is potential for use of codes that do not generate characteristic levels. In particular Model Code 90 is not prohibited, also Ven der Veen’s approach generates mean expectation of crack widths. There are some Contractors still purporting to MC90 and reviewer has a concern this will continue if left unchecked. Without guidance the Client is without a Captain and I uninformed. Note the NL Analysis is in accordance with EN so there should be no objection to using EN for crack widths. 2014.02.14 Webinar Mash ok as long as Charcateristic is the basis. Discuss Wu comment in Reno concerning reference to EN 1992-1-1. Webinar consensus was to include reference to EN 1992-1-1 for clarity.
34 Section 2.2.1 Page 7, Line # 31
1) Modeling
Jiang
Suggest to change to: 1) Modeling including modeling geometry and
material thermal properties
The comment found persuasive. Revise page 7 lines 20-21 to read.
1) “Modeling including specific tank geometry and material thermal properties”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
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37 Section 2.2.1 Page 8, Line # 2 4) Continue analysis until steady state final temperatures are reached
Jiang
Suggest to change to: 4) Continue analysis until steady state final temperatures are reached and the temperature distribution is obtained
The comment found persuasive. Revise page 7 lines 20-21 to read. 4) “Continue analysis until steady state final temperatures are reached temperature distribution is obtained”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Disagree - Garrison Committee needs to define analysis / design requirements. Considering the variability in the possible loading conditions, variability in material properties and variability in modeling techniques it seems that a steady state analysis would be sufficient. 2013.04.13 – 376-C Minneapolis: Withdrawn. 2014.02.14 Webinar ??????
41 Section 2.2.2 Page 8, Line # 8 “Apply dead load, prestressing and any other steady state load, iterate to equilibrium”
Jiang
Suggest to change to: “Apply dead, prestressing and any other steady state load”
The comment found persuasive. Revise page 7 lines 20-21 to read. “To establish initial conditions, aApply dead load, prestressing, normal-operating thermal and any other steady state load, then iterate to equilibrium”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Disagree - Garrison Committee needs to define analysis / design requirements. 2014.02.14 Webinar Mash delete "then iterate to equilibrium" is not losing anything Pg 8 line 11 & 13 delete as suggested.
44 Page 8, line 10, item 3
Mash
Determine strains in section, check for Residual Compressive Zone (RCZ), check for max comp stress etc.
The comment found persuasive. Change text to read: 5) “Beginning with the initial condition defined in step 2, cCompute crack widths at time steps times throughout the transient where reinforcing strains are the greatest. and exceed the material yield stress Furthermore, at each time step determine the adequacy of the compression zone.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan,
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 11 of 16
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
Krstulovic
Disagree - Garrison Considering the variability in the possible loading conditions, variability in material properties and variability in modeling techniques it seems that a steady state analysis would be sufficient.
47 Section 2.2.2 Page 8, Line # 11 5) Computer crack widths at times throughout the transient where reinforcing strains are the greatest and exceed the material yield stress
Jiang
Suggest to change to: 6) Computer crack widths at times throughout the transient where reinforcing strains are the greatest and the stresses exceed the material yield stress
2014.02.14 Webina straw poll Is Garrison negative persuasive? Yes - 0 No - 9 Abstain - 1
49 Page 8, line 18, item 7
Mash
What does this mean? The comment found persuasive. Change Page 8, lines 17-18 to read: “Calculation of cracking and crack widths for the RLG LNG spill condition and/or external fire condition shall be performed using a rational engineering analysis. Both linear Linear or non-linear finite element (FE) analysis should be used as discussed in 2.3.1 and 2.3.2.” 2014.02.14 Webinar Mash withdrawn Ballard comment : NKO comment is not relevant & discuss with Ballard in Reno. As written spill condition does not preclude spill + fire as per referenced code. Canadian code.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Garrison, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Disagree - Ballard CSA Z276 requires that fire and spill be considered concurrently. I believe that this needs to be addressed in this paragraph.
Disagree - Mash Rational to one uninformed Engineer could be irrational to informed Engineer. Rational requires defining. 2014.02.14 Webinar straw poll Mash withdrawn NKO regarding Ballard comment: It is not relevant & discuss with Ballard in Reno. As written spill condition does not preclude spill + fire as per referenced code, Canadian CSA Z276.
50 Section 2.3.1 Page 8, Lines # 21 to 23 “In this case a non-linear finite element program is used in conjunction with
Non-linear FE material constitutive models for
Jiang
Suggest to change to: “In this case a non-linear finite element program is used by:
Implementing the non-linear material constitutive relationship for concrete and steel
Carrying out FE analysis to obtain stress counters, and
Performing FE analysis post process to calculate crack width as per Eurocode 2 1992-1-1
The comment found persuasive. Change text to read: “In this case, a non-linear finite element program is used in conjunction with by:
Non-linear FE material constitutive models Implementing the non-linear material constitutive relationship for concrete and steel and
Carrying out FE analysis to obtain stress/strain contours, and
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 12 of 16
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
concrete and steel, and
Crack width calculations as per E
Performing FE analysis post-process to calculate characteristic crack width, calculations following a method, such as as per Eurocode 2 EN 1992-1-1 (see section 2.5 in this TN).”
Agree with minor changes - Khalifa
Performing FE analysis post-processing to calculate characteristic crack width, following a method, such as Eurocode 2 EN 1992-1-1 (see section 2.5 in this TN).”
Agree with minor changes - Ballard
Change word “contours” to “distribution” or change sentence to “Carrying out FE analysis to obtain stresses and strains.”
Agree with changes - Widianto
To be consistent with Sections 2.3.1 and 2.3.2, suggest the sentence is re-worded as follows: "Non-linear or simplified finite element (FE) analysis should be used as discussed in 2.3.1 and 2.3.2" To be consistent with the last sentence in Section 2.3, I suggest that we switch the order between the current Sections 2.3.1 and 2.3.2 (i.e., present Simplified FE analysis in Section 2.3.1 and present non-linear FE analysis in Section 2.3.2. This will also be consistent with the progression of the actual design, where Simplified FE analysis is done in the preliminary design, before non-linear FE analysis.
53 Section 2.3.2 Page 9, Lines # 2 & 3 “However, it should be noted that this is a very time consuming process and is thus usually used in the preliminary design.”
Jiang
Suggest to change to: “However, it should be noted that this is a very time consuming process and is thus usually used for focusing on more critical load cases after a preliminary screen for load cases has been performed in the preliminary design.”
The comment found persuasive. Remove the whole sentence. “However, it should be noted that this is a very time consuming process and is thus usually used for focusing on more critical load cases after a preliminary screen for load cases has been performed in the preliminary design.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 13 of 16
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
56 Section 2.3.2 Page 9, Lines # 4 & 5 “Moment-Curvature Approach: The moment curvature response is obtained using a concrete section analysis program in conjunction with:”
Jiang
Suggest to change to: “Moment-Curvature Approach: The moment curvature response is obtained using a concrete section analysis program by implementing:” Comment: Weather should this approach be considered as “Linear Analysis” or “Non-linear Analysis”? May be this approach could be considered as a simplified non-linear analysis approach and should be used for preliminary only.
The comment found persuasive. Change text to read: “2.3.2 Simplified Linear FE Analysis Simplified Linear FE analysis is usually used only in the preliminary design. …… “Moment-Curvature Approach: The moment curvature properties are response is obtained using a concrete section analysis program by implementing:” non-linear stress-strain material properties, and a non-linear shell formulation that accounts for the cracking
induced stiffness redistribution. This moment-curvature approach would only be suitable for
consideration of the steady state linear thermal gradient case and should also be used only for preliminary design.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
63 Page 9, line 34, item 4
Mash
Seems out of place in terms of the flow of the document. 2014.02.14 Webinar Oliver withdraw negative to editorial RP review if moving to another location
The comment found persuasive. Edit text as shown below: “2.3.4 Loading The RLG spill case should …… Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite difference solution. The thermal model used for determining nodal temperatures This thermal model is also a high density model which should include concrete foundation, soil thermal boundary condition, walls, roof and outside or inside ambient temperature boundary conditions. This model should also include the base slab insulation and the thermal corner protection insulation. “
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Pawski, Hatfield, Brannan, Krstulovic
Disagree - Oliver This response does not address the basic comment that this whole paragraph doesn’t below under “Loading”. Suggest moving it to Section 2.3.3 “Mesh Type and Size”, or inserting a new section before “Loading” called “Thermal Model”. 2014.02.14 Webinar straw poll Oliver negative withdrawn. Consider editorial. RP to review if another location is more appropriate considering concern.
66 A Page 10 Line 10
Hoptay
On the code side of ACI 376 ASTM A706 is not referred to as low temperature reinforcing, only in the commentary. Can it be referred to as low temperature reinforcing in the technical note?
The comment found persuasive. Change text to read: “The concrete wall internal temperatures from the thermal model are also typically used for selection and to determine the placement of normal (A615), cold-temperature (A706) and cryogenic reinforcing complying with the requirements of ACI 376.” Furthermore, in a future Coed revision, revisit the use of A706 materials in ACI 376 section 4.7.2.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 14 of 16
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
74
Garrison
1) Code and TN need to define conditions for transient thermal analysis for the spill condition (leak rate).
2) Why does TN reference withdrawn version of Eurocode
2 (DD ENV 1992-1-1:1992)? Current version is BS EN 1992-1-1:2004.
The comment found partially persuasive. 1) Definition of the spill loading is beyond the scope of the current TN
and will thus be addressed in a separate document defining LNG spill conditions.
2) Update and change the model to the latest 2004 edition of the Eurocode,
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with comment - Ballard
Garrison was going to forward a copy of EN 1992-1-1:2004 to Ballard for updating the code equations in the TN.
???? - Garrison Agreed, loading and consideration of need for transient analyses needs to be reviewed. 2014.02.14 Webinar ??????
75 Appendix A Pages 15-16
Pawski
It is redundant because it repeats paragraphs 2 through 4 in section 2.1 (page 7, lines 9-21)
The comment found non-persuasive. The comment found to be an editorial comment. Appendix A is a “copy” of what is in the Code. It is provided for reader’s convenience.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
76 Page 16, last paragraph in section R8.1.1.7
Thompson
Remove the last sentence from the Code Commentary: “Due to the non-homogeneous nature of concrete, calculated crack width values measured in the field will vary from calculated values, and therefore they cannot be directly compared to calculated crack widths.”
Section R8.1.1.7 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 15 of 16
ADDITIONAL COMMENTS included with the ballots
Ref No.
Text Author Comments 2ND BALLOT:
RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS Page 4, line 8; Section 1.1
Oliver EDITORIAL: Add “the” “The primary function of TCP is to protect the already highly…”
Page 6, Lines 28 - 30 Hoff Can we provide some guidance to the owner in this section? 10-21: Hoff comment resolution: The crack width requirements in section 6 are provided to for this purpose. DELETE 1.2.4
Hjorteset Wu Biily Brannan Pawski Howe Garrison Hoff Hanskat
Wu
The liquid tightness criteria are specified in Section 2.1, Items 1 & 2. Why do we need additional tightness criteria on “embedment plates” to be defined by owner?
Page 7, line 8 Pawski
Referenced section does not match final 376-10 1) ACI 376 section 6.3.3 6.3.2”
Page 7, line 14 Pawski
Referenced section does not match final 376-10 2) ACI 376 section 6.3.4 6.3.3”
77 Page 9, section 2.3.3, lines 19, Khalifa Add ‘separate’ before ‘model’ for clarity. 78 Page 8, section 2.3.1, line32, 33
Khalifa Revise to: Either a proprietary or one of several commercially available FE programs can be used for performing this calculation.
Page 9, line 24 Hoff
Change this sentence to read: “If Liners are considered as structural members, they should be included if they are considered as structural members too.”
10-21-13 editorial
Page 10, line 28 Pawski
Use “should” in a non-mandatory TN “Recognized concrete constitutive models shall should be used in the analysis.”
10-21-13 editorial
79 Page 10, section 2.4.1, line 30 Khalifa
Revise to: …account for reduction in tensile stiffness after cracking of concrete including the effects of tension stiffening.
10-21-13 Account for reduction in tensile stiffness after cracking of concrete .
Page 11, line 7 Hoff, Widianto
The stress symbols are missing 10-21-13 editorial
Page 12, lines 10, 11
Hoff
Change to read: “Since For the RLG spill case, it is critical that cryogenic liquid be prevented from migrating behind the TCP, and conservative assumptions should be used when selecting material properties.”
10-21-13 editorial
Page 13, Section 2.5
Wu
The specified Code, EN2 part 1- 4.4.2.4 does not contain the equations for crack width calculation. The crack width calculation is shown in Section 7.3.4 of EN 1992-1-1 (2004 edition). Also, the equations shown here are not the same as the equations shown in EN 1992-1-1 (2004 edition). Please provide clarification.
10-21-13 Modify to address to match code and equations. Same as item 74
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 2 / 14 / 2014 - 376-D webinar Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 16 of 16
To be addressed as future business:
Author Comments Legatos Conspicuous by its absence in the TCP-TN write-up is any reference to outer-wall designs that incorporate an impervious, continuous liquid-tight and vapor-tight liner.
This omission overlooks the crucial role such a liner plays in the formulation of criteria and parameters as they pertain to (a) the serviceability of the outer wall following a spill and/or thermal shock; (b) the specified limits on crack-width, residual wall compression, etc., etc.; and (c) the function, scope and design of the TCP itself. Moreover, this omission overlooks the differences between inner-versus-outer, and metallic-versus-non-metallic liners; and the role these differences similarly play in (a) through (c) above. If I am not mistaken, the only Code section that fleetingly mentions this subject with respect to the TCP is Section 6.3.3. This article provides guidance on what to do if a “leak-tight membrane/liner” is not used, but does not say anything about what to do in cases where such a liner is in fact used. The subject is also covered in 6.3.16.1 1nd 16.3.16.2, but those sections do not relate to the TCP. While I have not thoroughly perused the rest of the Code itself to see exactly where else this subject “belongs” and how it should be covered, I believe that TCP-TN coverage might fit in the following sections:
Section 1.1 (add a fifth paragraph) Fig. 1.1 (add Fig. 1.1 c) Section 1.2.4 Section 2.1
2014.02.14 Webinar Discuss NAL negative in Reno. Note - subsequent to webinar NAL staed he would provide draft wording.
ACI 376 TCP Design & Analysis
1 11 / 16 / 2011
ACI 376 Technical Note on 1
Thermal Corner Protection Design & Crack Analysis 2
3
Reported by ACI Committee 376 4
5
Concrete Structures for Refrigerated Liquefied Gas Containment 6
7
* Contributing Member 8
9
INTRODUCTION 10
ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner 11
Protection (TCP). The purpose of this document is to provide further guidance on (a) TCP detailing and 12
(b) TCP liquid-tightness analysis (i.e., crack width calculations). The document therefore consists of 13
two parts: 14 15
1. Part 1 – Detailing & Construction Issues: TCP detailing and related design issues are presented in 16
the first part of this document 17 18
Neven Krstulovic-Opara*
Chair
Piotr D. Moncarz
Secretary
Junius Allen
Thomas A. Ballard*
Dale Berner
Mike S. Brannan
Hamish Douglas*
Jeffrey Garrison*
Charles S. Hanskat
Alan D. Hatfield
Humayun Hashmi
Kare Hjorteset
George C. Hoff*
Richard Hoffmann
John Holleyoak
Joseph M. Hoptay*
Thomas R. Howe
Dajiu Jiang
Jameel U. Khalifa
Nicholas A. Legatos
Praveen K. Malhotra
Keith A. Mash*
Stephen W. Meier
Robert W. Nussmeier
Rolf P. Pawski*
Ramanujam S. Rajan
William E. Rushing
Robert W. Sward
Eric S. Thompson
Sheng-Chi Wu
ACI 376 TCP Design & Analysis
2 11 / 16 / 2011
2. Part 2 – Crack Width for Liquid Tightness: One of the key TCP-performance criteria is related to 1
assuring adequate liquid tightness during a spill condition. ACI 376 Code specifies liquid tightness 2
limits in terms of limiting concrete crack widths. The liquid tightness / crack width analysis 3
procedure is presented in the second part of this document, followed by an example outlining 4
proposed analysis steps that would meet ACI 376 Code requirements. 5
6
ACI 376 TCP Design & Analysis
3 11 / 16 / 2011
CONTENTS 1
2
INTRODUCTION 3
4
CHAPTER 1 � TCP DESIGN 5
1.1—General 6
1.2—Embedment Plate and Anchor Studs 7
8
CHAPTER 2 � LIQUID TIGHTNESS AND CRACK WIDTH ANALYSIS 9
2.1—General 10
2.2—Analysis Procedure 11
2.3—Numerical Model 12
2.4—Material Constitutive Models 13
2.5—Crack Width Calculations 14
15
APENDICES 16
17
APENDIX A � ACI 376 TCP CODE ERQUIREMENTS 18
19
REFERENCES 20
21
A
1
2
3
4
5
16
T7
s8
s9
b10
c11
12
T13
F14
a15
e16
d17
ACI 376
1.1—Genera
The thermal c
secondary con
stressed wall
both (a) a liq
cryogenic tem
The TCP is c
Figure 1.1 a.
as shown in
embedment w
designed to re
al
corner protec
ncrete wall, a
to slab joint f
quid and (b) a
mperatures dur
connected to
The TCP is a
Figure 1.1 b
will be subje
emain intact a
C
a)
Figure 1
ction (TCP) i
as shown in
from addition
a thermal bar
ring a spill co
a secondary
attached to th
b. During th
ected to signi
and in place d
CHAPTER
.1: Thermal C
s an insulated
Figure 1.1 a
nal thermal lo
rrier at the w
ondition.
bottom plate
e concrete wa
he spill condi
ificant therm
during the spil
4
R 1 – TCP
Corner Protec
d and liquid
a. The primar
oads during sp
wall to slab jo
e that provid
all through an
ition, the con
mal and mech
ll condition.
P Design
ction (TCP) D
tight system
ry function o
pill condition
oint, thus pro
es a liquid b
n embedment
ncrete wall a
hanical loads
b)
Detail
located at th
of TCP is to
ns. The TCP
otecting the j
barrier above
t plate located
above the TC
. The TCP e
TCP Design
11 / 16 / 20
he bottom of
protect alrea
is designed t
joint from ex
the slab, as
d at the top of
CP, the TCP
embedment s
& Analysis
011
f the outer
ady highly
to provide
xposure to
shown in
f the TCP,
and TCP
should be
ACI 376 TCP Design & Analysis
5 11 / 16 / 2011
1
The concrete wall above the TCP, directly exposed to spilled product, should remain liquid and substantially 2
vapor tight during the spill condition. This is assured by limiting cracking in the vicinity of the TCP embedment 3
plate during a spill. 4
5
The scope of this section is to provide guidelines and best practices for the detailing of the TCP region, i.e., the 6
TCP, the TCP embedment plate and TCP embedment plate anchorage to the outer concrete wall. Information is 7
provided for the evaluation of the embedment plate, design of the anchor studs and attachment to the concrete 8
wall, and for the evaluation of cracking in the embedment zone. Material selection and material requirements 9
used in the design of the 9% nickel-steel TCP and secondary bottom plates may be performed in accordance with 10
API 620. 11
12
1.2—Embedment Plate and Anchor Studs 13
The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both 14
(a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition. The TCP design 15
consists of the following steps: 16
17
1.2.1 - STEP 1: TCP Load Definition 18
Finite element analyses is performed first to determine forces resulting from thermal gradients applied to the 19
TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the 20
embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, 21
hydrostatic pressure. 22
Various spill levels should be considered to determine the most severe effect on the embedment and concrete 23
wall. This should include spill levels below the top of the TCP which will place the largest temperature 24
differential between the TCP and the concrete wall as well as various spill levels above the TCP up to the full 25
spill level. 26
The analysis should be based on both steady state and transient conditions, as specified in ACI 376 Code section 27
8.4.8. R8.4.8 specifically indicates that during transient conditions an embedment such as the TCP will frequently 28
experience the greatest self-straining forces. 29
30
1.2.2 - STEP 2: Embedment Plate Design 31
The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall or by other 32
suitable means (e.g., ???). Anchor bolts (studs) should be placed in continuous (circumferential) rows along 33
the concrete wall. 34
ACI 376 TCP Design & Analysis
6 11 / 16 / 2011
When the embedment plate is anchored with circumferential studs, a minimum of two rows of studs should be 1
used to anchor the embedment plate. The spacing between mechanical anchors (studs) should be limited to 2
ensure that the axial, bending and shear stresses in the embedment plate are within the allowable stresses. 3
Embedment plate and mechanical anchor material as well as the TCP material should be suitable for the 4
product temperature. 5
Allowable stresses i.e., material selection and material requirements used in the design of the embedment 6
plates, may be selected in accordance with API 620. 7
8
1.2.3 - STEP 3: Anchor Bolt Design 9
The mechanical anchors bolts (studs) and concrete at the anchor location should meet the requirement for 10
anchoring to the concrete wall defined in the ACI 350 Appendix D. 11
The steel strength of the anchor in tension should be as per ACI 350 section D.5.1. 12
The concrete breakout strength of the anchor in tension should be checked per ACI 350 section D.5.2. 13
The pullout strength of the anchor in tension should be checked per ACI 350 section D.5.3. 14
The steel strength of the anchor in shear should be checked per ACI 350 section D.6.1. 15
The concrete breakout strength of the anchor in shear should be checked per ACI 350 section D.6.2. 16
The concrete pry-out strength of the anchor in shear should be checked per ACI 350 section D.6.3. 17
Interaction of tensile and shear forces should be checked per ACI 350 section D.7. 18
19
20
ACI 376 TCP Design & Analysis
7 11 / 16 / 2011
CHAPTER 2 – PART 2: Liquid Tightness and Crack Width Analysis 1
2
2.1—General 3
When subjected to the spill condition, the concrete wall will be loaded with high thermal and mechanical forces. 4
These forces will lead to significant wall cracking. During the spill condition, integrity of the concrete wall must 5
be maintained. As specified in the ACI 376 Code, the wall should remain liquid and vapor tight. More 6
specifically: 7
8
1) ACI 376 section 6.3.3: “Unless a leak-tight membrane/liner has been used, a minimum portion of the concrete 9
should remain in compression in accordance with the following: 10
a) A compressive zone of either 10% of the section thickness or 3.5 in., whichever is greater should be provided; and 11
b) A minimum average compressive stress within the compressive zone of 145 lb/in2 should be maintained.” 12
13
2) ACI 376 section 6.3.4: “Calculated crack widths should be considered at TCP embedment when cracking would 14
result in liquid product migrating behind the TCP and compromising its effectiveness. The embedment zone should 15
extend a minimum of two times the wall thickness above the TCP anchorage. Calculated crack widths should not 16
exceed 0.008 in. within the TCP embedment zone. Recommendations for crack width calculations are provided in 17
8.1.1.8.” 18
19
3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean 20
calculated crack widths as per EN 1992-1-1. 21
22
Non-linear finite element analysis should be performed to ensure that these requirements are met. 23
24
25
2.2—Analysis Procedure 26
The analysis procedure consists of the following steps: 27
28
2.2.1 - STEP 1: Thermal Analysis 29
Thermal analysis is performed using Finite Element or Finite Difference approach. Steps include: 30
1) Modeling 31
2) Thermal boundary condition definition/application to equilibrium 32
3) Application of LNG spill or external fire temperature loads obtained by considering rate of leakage into 33
annular space and exposed to transient temperatures 34
ACI 376 TCP Design & Analysis
8 11 / 16 / 2011
1
4) Continue analysis until steady state final temperatures are reached 2
5) Repeat for all thermal load cases 3
4
2.2.2 - STEP 2: Structural Analysis 5
Structural Analysis is performed using the Finite Element approach. Steps include 6
1) Modeling 7
2) Apply dead load, prestressing and any other steady state load, iterate to equilibrium 8
3) Check crack widths 9
4) Apply LNG spill temperature transients and iterate to equilibrium 10
5) Compute crack widths at times throughout the transient where reinforcing strains are the greatest and 11
exceed the material yield stress 12
6) Repeat for all thermal load cases 13
14
15
2.3—Numerical Model 16
Calculation of cracking and crack widths for the LNG spill condition and/or external fire condition shall be 17
performed using a rational engineering analysis. Both linear or non-linear finite element (FE) analysis 18
19
2.3.1 Non-Linear FE Analysis 20
In this case a non-linear finite element program is used in conjunction with 21
non-linear FE material constitutive models for concrete and steel, and 22
crack width calculations as per Eurocode 2 1992-1-1. 23
Either a proprietary or a commercially available FE programs can be used. There are several commercially 24
available FE programs that are adequate for performing this calculation. A few of more widely used non-linear 25
FE programs available in the United States include ANSYS1, ABACUS2, ADINA3 and NX NASTRAN4. There 26
are also many proprietary FE programs that have been designed specifically to consider the cracking problem for 27
reinforced concrete containment structures. 28
29
2.3.2 Linear FE Analysis 30
Linear FE analysis is usually used only in the preliminary design. Two possible approaches include: 31
ACI 376 TCP Design & Analysis
9 11 / 16 / 2011
a) Reduced-Stiffness / Cracked-Section Approach: The calculation is performed using a linear finite element 1
analysis where the reduction in stiffness due to cracking is considered. However, it should be noted that this 2
is a very time consuming process and is thus usually only used in the preliminary design. 3
b) Moment-Curvature Approach: The moment curvature response is obtained using a concrete section 4
analysis program in conjunction with: 5
non-linear stress-strain material properties, and 6
a non-linear shell formulation that accounts for the cracking induced stiffness redistribution. 7
This moment-curvature approach would only be suitable for consideration of the steady state linear 8
thermal gradient case and should also be used only for preliminary design. 9
10
2.3.3 Mesh Type and Size 11
The linear or non-linear FE model will usually be axisymmetric or a small slice 3D model of the containment for 12
consideration of the general case of a symmetric LNG spill loads and a larger sector model for consideration of 13
the LNG spill case where non-axisymmetric discontinuities are considered. 14
15
Typically, the structural model contains a fine-mesh or a high density of solution points. The model includes the 16
base slab, foundation springs, containment wall, roof structure and local discontinuities, such as the prestressing 17
buttresses. If the liners are considered as structural members, they should be included too. 18
19
A more detailed substructure model of the region above the TCP anchorage might be considered in order to 20
reduce the computational demand, provided it can be demonstrated that the boundary conditions and loadings 21
correctly represent the global model. 22
23
The reinforcing and prestressing steel may also be modeled and the prestressing forces applied as part of the 24
loading or construction sequence. 25
26
2.3.4 Loading 27
The LNG spill case should include hydrostatic pressure from the LNG fluid in the annular space. Dead load, live 28
load and steady state temperatures coincident prior to the LNG spill, shall be applied prior application of the 29
temperature transients. 30
31
32
Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite 33
difference solution. This thermal model is also a high density model which should include concrete foundation, 34
ACI 376 TCP Design & Analysis
10 11 / 16 / 2011
soil thermal boundary condition, walls, roof and outside or inside ambient temperature boundary conditions. This 1
model should also include the base slab insulation and the thermal corner protection insulation. 2
3
2.3.5 Heat Analysis 4
The heat transfer analyses should consider both maximum (95th percentile) and minimum (5th percentile) ambient 5
temperatures. The LNG spill is applied internally to the containment and the adjacent tank fire case is applied 6
externally. The LNG spill load case should also include the vapor temperature generated from the spill above the 7
liquid level. Nodal temperature time histories are computed and mapped to the structural finite element model. 8
The concrete wall internal temperatures from the thermal model are also typically used to determine the 9
placement of normal (A615), cold-temperature (A706) and cryogenic reinforcing complying with the 10
requirements of ACI 376. 11
12
The LNG hydrostatic pressure and temperature time histories are applied gradually and the iterative solution 13
computes concrete stresses and strains, crack locations and reinforcing stresses. 14
15
16
2.4—Material Constitutive Models 17
18
2.4.1 Concrete Constitutive Model 19
Recognized concrete constitutive models shall be used in the analysis. Examples include material models 20
described by Eurocode 25 and shown in the Figure 2.1 below. The concrete constitutive model should also 21
account for linear tension stiffness effects with tension failure or reduction in stiffness at the cracking strain of the 22
concrete. 23
24
Figure 2.1: Stress-Strain Diagram for Uniaxial Compression from Eurocode 2 1992-1-1 25
A
1
T2
3
F4
w5
6
T7
w8
9
I10
n11
12
213
ACI 376
The c – c m
For short term
c/fc
where:
fc
cu
n
c1
k
Ec,nom
c
Ecm
The tension si
c
c
where:
fctm
In reality, the
numerical stab
2.4.2 Steel C
material relatio
m loading the
= (k.n-n2)/[1 +
concrete
ultimate s
= c/c1 (b
= -0.0022
= (1.1Ec,n
= Ecm/c (
partial sa
= 9.5(fc +
ide of the �c –
= Ecmc (N/m
= 0 for c > o
= 0.30fc2/3 (N
tension softe
bility in the so
Constitutive
onship shown
relationship i
+ n.(k-2)]
compressive
strain < 0.0
both < 0.0)
2 (strain at the
nom).c1/fc
kN/mm2)
fety factor = 1
8)1/3 (Ecm in k
– �c material
mm2) for c < f
or = fctm
/mm2)
ning is usuall
olution.
Models
n in Figure 2.1
is defined as:
strength at 2
e peak stress
1.5 unless jus
kN/mm2; fc in
l relationship
fctm
ly introduced
11
1 is taken from
28 days (N/mm
fc)
stified by adeq
N/mm2)
may be taken
following rup
m Eurocode 2
m2) < 0.0
quate control
n as:
upture of the c
2 Part 1, 4.2.1
procedures.
concrete in or
TCP Design
11 / 16 / 20
1.3.1 (4.1).
(1
(2
(3
(4
(5
(6
(7
(8
(9
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(11
(13
der to provide
& Analysis
011
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2)
3)
4)
5)
6)
7)
8)
9)
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)
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A
F1
s2
3
4
5
O6
a7
8
29
S10
c11
12
213
I14
T15
m16
17
218
F19
w20
p21
o22
ACI 376
Figure 2.2 sho
strain curve fo
Figure 2.2:
Reinforc
Other concret
accurately cha
2.4.3 Selecti
Since for the
conservative a
2.4.3.1 - Com
It should be n
Therefore, the
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2.4.3.2 - Tens
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width. Also,
percentile con
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Typical Unia
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aracterize mat
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asticity of the
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, if tensile st
ncrete tensile
te in the analy
uniaxial stres
g steel.
axial Stress-St
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terial behavio
rial Parame
case, it is crit
should be use
sponse
e extent of th
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es
minimum yie
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ysis.
ss strain curve
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2 1992-1-1
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or.
eter Values
tical that cryo
ed when selec
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ssive concrete
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eld strength o
he concrete is
ts. A more co
12
e for reinforci
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ting material
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re 2.3: Typica
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al Uniaxial St
teel from Euro
be demonstra
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as the size an
crack width c
lso considere
be considered
is should eva
uld be to consi
TCP Design
11 / 16 / 20
typical uniaxi
tress-Strain C
ocode 2 1992
ated that thes
ating behind
nd extent of th
calculations.
d adequate.
to maximize
aluate the 95
ider no tensile
& Analysis
011
ial stress-
Curve for
2-1-1
se models
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he cracks.
The mean
e the crack
5th and 5th
e capacity
ACI 376 TCP Design & Analysis
13 11 / 16 / 2011
1
2.4.3.3 - Temperature Effects on Material Properties 2
Improved material properties at low temperature, should not be used unless adequate cryogenic testing has been 3
carried out to confirm these material properties. The variation of the mean coefficient of thermal expansion with 4
temperature should also be considered in the solution. 5
6
7
2.5—Crack Width Calculations 8
The Code suggests that Eurocode 2 Part 1 4.4.2.4, (4.80) be the basis for calculation of crack widths. In this 9
approach crack width is determined from steel strains using the following relationship: 10
wk = srmsm (14)
where wk is the 95th percentile crack width, sm is the mean steel strain, srm is the average final crack spacing and 11
is a design value that can be taken as: 12
1.7 for load induced cracking and for restraint cracking in section with minimum dimension in excess of 800 13
mm, or 14
1.3 for restraint cracking in sections with a minimum dimension depth, breadth or thickness, (whichever is the 15
lesser) of 300 mm or less. 16
17
The average final crack spacing, srm, is computed from Eurocode 2 Part 1, 4.4.2.4 (4.82) as: 18
srm = 50 + 0.25k1kk2/r (15)
where: 19
is the barsize or average bar size in mm (16)
k1 = 0.8 for high bond bars and 1.6 for plain bars (17)
k = 0.8 for tensile stresses that are due to intrinsic deformations (18)
k2 is a coefficient which accounts for the form of the strain distribution and is between
0.5 for bending and 1.0 for pure tension.
(19)
r is the effective reinforcing ratio, As/Ac,eff, where As is the area of reinforcement
contained within the effective tension area, Ac,eff
(20)
20
The mean strain value, sm, should be computed directly using the non-linear finite element model and considering 21
all loads existing at the time of cracking. More specifically, the mean strain is obtained by averaging calculated 22
strain over the length of steel that has exceeded the yield limit. In other words, for a single piece of reinforcing 23
steel that has exceeded yield, sm would be computed as the integrated strain over the length of the plastic zone of 24
the reinforcing divided by the length of the plastic zone. 25
ACI 376 TCP Design & Analysis
14 11 / 16 / 2011
REFERNCES 1
1. ANSYS Inc., Canonsburg, PA 2
2. ABACUS, Inc., Providence, RI 3
3. ADINA R & D, Inc., Watertown, MA 4
4. Siemens PLM Software, Plano TX 5
5. EUROCODE 2 Design of concrete structures – Part 1 General rules and rules for buildings 6
7
8
ACI 376 TCP Design & Analysis
15 11 / 16 / 2011
1
Appendix A: ACI 376 Code TCP Requirements 2
3
CHAPTER 2—NOTATION AND TERMINOLOGY
thermal corner protection (TCP)—insulated and liquid tight system to protect the outer
tank from thermal shock.
calculated crack width—crack width calculated using a concrete constitutive model
defined in 8.1.1.7.
CHAPTER 6—MINIMUM PERFORMANCE REQUIREMENTS
6.3.2—Under spill conditions, the concrete above the thermal corner protection (TCP)
should remain liquid tight, based upon minimum depths of compression and
precompression.
6.3.4—Calculated crack widths should be considered at TCP embedment when cracking
would result in liquid product migrating behind the TCP and compromising its
effectiveness.
The embedment zone should extend a minimum of two times the wall thickness above the
TCP anchorage. Calculated crack widths should not exceed 0.004 in. within the TCP
embedment
zone.
CHAPTER 8—ANALYSIS & DESIGN
8.1.1.7—Cracking and tension stiffening
should be included by appropriate
modification of the material stress strain
relationship or by the use of finite elements
R8.1.1.7—The Eurocode 2 is recommended
for determining calculated crack widths. In
this case, the calculated crack widths are
characteristic and not mean calculated crack
ACI 376 TCP Design & Analysis
16 11 / 16 / 2011
that have the capability of cracking under
tension, and crushing under compression as
well as the ability to include reinforcing
steel.
Unless otherwise specified, the concrete
constitutive mode from European Code
should be used for determining calculated
crack widths.
widths.
Extensive field experience with liquid
retaining and offshore concrete structures
has demonstrated that satisfactory liquid
tightness and liquid retaining performance
can be achieved by imposing calculated
crack width limits.
However, it must be noted that calculated
crack width represents an average numerical
value that is not directly equivalent to
calculated crack width measured in the field.
Due to the non-homogeneous nature of
concrete, calculated crack width values
measured in the field will vary from
calculated values, and therefore they cannot
be directly compared to calculated crack
widths.
1
A
1
2
ACI 376
17
TCP Design
11 / 16 / 20
& Analysis
011
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 1 11 / 16 / 2011 (2nd ballot)
ACI 376 Technical Note on 1
Design and Analysis of the TCP Embedment Zone 2
3
Reported by ACI Committee 376 4
5
Concrete Structures for Refrigerated Liquefied Gas Containment 6
7
* Contributing Member 8
9
INTRODUCTION 10
ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner 11
Protection (TCP) embedment zone. The purpose of this Technical Note is to provide further guidance 12
for (a) design and analysis of theTCP anchorage and (b) liquid-tightness analysis in the TCP embedment 13
zone (i.e., crack width calculations). The document therefore consists of two parts: 14
15
1. Part 1 – Detailing & Construction Issues: TCP detailing and related design issues are presented in 16
the first part of this document 17
18
Neven Krstulovic-Opara*
Chair
Piotr D. Moncarz
Secretary
Junius Allen
Thomas A. Ballard*
Dale Berner
Mike S. Brannan
Hamish Douglas*
Jeffrey Garrison*
Charles S. Hanskat
Alan D. Hatfield
Humayun Hashmi
Kare Hjorteset
George C. Hoff*
Richard Hoffmann
John Holleyoak
Joseph M. Hoptay*
Thomas R. Howe
Dajiu Jiang
Jameel U. Khalifa
Nicholas A. Legatos
Praveen K. Malhotra
Keith A. Mash*
Stephen W. Meier
Robert W. Nussmeier
Rolf P. Pawski*
Ramanujam S. Rajan
William E. Rushing
Robert W. Sward
Eric S. Thompson
Sheng-Chi Wu
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 2 11 / 16 / 2011 (2nd ballot)
2. Part 2 – Crack Width for Liquid Tightness: One of the key TCP-performance criteria is related to 1
assuring adequate liquid tightness during a spill condition. ACI 376 Code specifies liquid tightness 2
limits in terms of limiting concrete crack widths. The liquid tightness / crack width analysis 3
procedure is presented in the second part of this document, followed by an example outlining 4
proposed analysis steps that would meet ACI 376 Code requirements. 5
6
Although the code and this TN do not explicitly define leak tightness criteria for the anchorage and 7
embeddment, the design and construction of these components should be carried out with the clear 8
objective of protecting the corner joint from product temperatures. 9
10
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 3 11 / 16 / 2011 (2nd ballot)
CONTENTS 1
2
INTRODUCTION 3
4
CHAPTER 1 ———— TCP DESIGN 5
1.1—General 6
1.2—Embedment Plate and Anchorage 7
8
CHAPTER 2 ———— LIQUID TIGHTNESS AND CRACK WIDTH ANALYSIS 9
2.1—General 10
2.2—Analysis Procedure 11
2.3—Numerical Model 12
2.4—Material Constitutive Models 13
2.5—Crack Width Calculations 14
15
APENDICES 16
17
APENDIX A ———— ACI 376 TCP CODE ERQUIREMENTS 18
19
REFERENCES 20
21
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 4 11 / 16 / 2011 (2nd ballot)
CHAPTER 1 – TCP Design 1
2
a) b)
3
Figure 1.1: Thermal Corner Protection (TCP) Detail 4
5
1.1—General 6
The thermal corner protection (TCP) is an insulated and liquid tight system located at the bottom of the outer 7
secondary concrete wall, as shown in Figure 1.1 a. The primary function of TCP is to protect the already highly 8
stressed wall to slab joint from additional thermal loads during spill conditions. The TCP is designed to provide 9
both (a) a liquid and (b) a thermal barrier at the wall to slab joint, thus protecting the joint from exposure to 10
cryogenic temperatures during a spill condition. 11
12
The TCP is connected to a secondary bottom plate that provides a liquid barrier above the slab, as shown in 13
Figure 1.1 a. The TCP is attached to the concrete wall through an embedment plate located at the top of the TCP, 14
as shown in Figure 1.1 b. During the spill condition, the concrete wall above the TCP, the TCP and TCP 15
embedment will be subjected to significant thermal and mechanical loads. The TCP embedment should be 16
designed to remain functional and in place during the spill condition. 17
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 5 11 / 16 / 2011 (2nd ballot)
1
The concrete wall above the TCP, directly exposed to spilled product, should remain liquid tight and substantially 2
vapor tight during the spill condition. This is assured by maintaining a compression zone in the wall exposed to 3
the spill and by limiting crack width on the inside face of the wall in the TCP embedment zone plate during a spill. 4
5
The scope of this section is to provide guidelines and best practices for the detailing of the TCP region, i.e., the 6
TCP, the TCP embedment plate and TCP embedment plate anchorage to the outer concrete wall. Information is 7
provided for the evaluation of the embedment plate, design of anchors and attachment to the concrete wall, and 8
for the evaluation of cracking in the embedment zone. 9
10
1.2—Embedment Plate and Anchors 11
The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both 12
(a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition including SSEAFT. 13
The TCP design consists of the following steps: 14
15
1.2.1 - STEP 1: TCP Load Definition 16
• Finite element analyses are performed first to determine forces resulting from thermal gradients applied to the 17
TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the 18
embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, 19
hydrostatic pressure and hydrodynamic pressure due to seismic aftershock (SSEAFT). Initial temperatures and 20
conditions should be selected so as to maximize the demand under consideration. For instance for the design 21
of the anchors the critical condition is likely to be warm wall (summer) a cold thermal shock to the 22
embedment, thereby creating maximum strain across the section. 23
• Various spill levels should be considered to determine the most severe effect on the embedment and concrete 24
wall. This should include a spill level located just below the top of the TCP which will place the largest 25
temperature differential between the TCP and the concrete. A minimum of three levels should be considered 26
for spill levels above the TCP, 1) at top of the TCP embedment zone, 2) at mid-height, and 3) at full spill 27
level. 28
• The analysis should be based on both steady state and transient conditions, as specified in ACI 376 Code section 29
8.4.8. R8.4.8 specifically indicates that during transient conditions an embedment such as the TCP will frequently 30
experience the greatest self-straining forces. 31
32
1.2.2 - STEP 2: Embedment Plate Design 33
• The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall. 34
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 6 11 / 16 / 2011 (2nd ballot)
• The embedment plate should be anchored with a minimum of two rows of circumferential anchors. The 1
spacing between anchors has significant impact on the TCP embedment performance and thus should be 2
considered in design. 3
• Embedment plate and mechanical anchor material as well as the TCP material should be suitable for the 4
product temperature. 5
• Allowable stresses i.e., material selection and material requirements used in the design of the embedment 6
plates, may be selected in accordance with API 620. 7
• Anchor spacings should be selected so as to be multiples of the bar spacing to enable a clash-free design. 8
9
1.2.3 - STEP 3: Anchorage Design 10
The mechanical anchorage (anchors bolts or studs) and concrete at the anchor location should meet the 11
requirement for anchoring to the concrete wall defined in the ACI 350 Appendix D. 12
13
1.2.4 - STEP 4: Li quid Tightness 14
Liquid tightness at the embedment plate should be considered in the details and design of the anchorage as 15
defined by the owner. 16
17
Note - consesus at 2013.10.21 Phoenix meeting was new "1.2.4 Step 4" is not needed and
should be deleted in its entirety. Shown for information and is to be deleted.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 7 11 / 16 / 2011 (2nd ballot)
CHAPTER 2 – PART 2: Liquid Tightness and Crack Width Analysis 1
2
2.1—General 3
During the spill condition, the secondary concrete wall will be subjected to high large forces due to mechanical 4
loads and thermal effects that will lead to significant wall cracking. Integrity of the concrete wall must be 5
maintained. As specified in the ACI 376 Code, the wall should remain liquid and substantially vapor tight. More 6
specifically: 7
1) ACI 376 section 6.3.2: “Unless a leak-tight membrane/liner has been used, a minimum portion of the concrete 8
should remain in compression in accordance with the following: 9
a) A compressive zone of either 10% of the section thickness or 3.5 in., whichever is greater shall be provided; and 10
b) A minimum average compressive stress within the compressive zone of 145 lb/in2 should be maintained.” 11
12
2) ACI 376 section 6.3.3: “Calculated crack widths should be considered at TCP embedment when cracking would 13
result in liquid product migrating behind the TCP and compromising its effectiveness. The embedment zone should 14
extend a minimum of two times the wall thickness above the TCP anchorage. Calculated crack widths should not 15
exceed 0.008 in. within the TCP embedment zone. Recommendations for crack width calculations are provided in 16
8.1.1.8.” 17
18
3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean 19
crack widths. 20
21
Non-linear finite element analysis should be performed to ensure that these requirements are met. 22
23
24
2.2—Analysis Procedure 25
The analysis procedure consists of the following steps: 26
27
2.2.1 - STEP 1: Thermal Analysis 28
Thermal analysis is performed based on a thermal model using Finite Element or Finite Difference approach. 29
Steps include: 30
1) Modeling including specific tank geometry and material thermal properties 31
2) Thermal boundary condition definition/application to equilibrium 32
3) Application of RLG spill temperature loads obtained by considering rate of leakage into annular space 33
and exposed to transient temperatures 34
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 8 11 / 16 / 2011 (2nd ballot)
1
4) Continue analysis until steady state temperature distribution is obtained 2
5) Repeat for all thermal load cases 3
4
2.2.2 - STEP 2: Structural Analysis 5
Structural Analysis is performed based on the stress model using the Finite Element approach. Steps include 6
1) Modeling 7
2) To establish intiial conditions, apply dead load, prestressing, normal opearting thermal and any other 8
steady state load, then iterate to equilibrium 9
3) Apply RLG spill temperature transients and iterate to equilibrium 10
4) Beginning with the intial condition defined in step 2, compute crack widths at time-steps throughout the 11
transient where reinforcing strains are the greatest . Furthermore, at each time step determine the adequacy of 12
the compression zone. 13
5) Repeat for all thermal load cases 14
15
16
2.3—Numerical Model 17
Calculation of cracking and crack widths for the RLG spill condition shall be performed using a rational 18
engineering analysis. Linear or non-linear finite element (FE) analysis should be used as discussed in 2.3.1 and 19
2.3.2. 20
21
2.3.1 Non-Linear FE Analysis 22
In this case a non-linear finite element program is used by: 23
• Implementing the non-linear material constitutive relationship for concrete and steel, 24
• Carrying out FE analysis to obtainstress/strain contours, and 25
• Performing FE analysis post process to calculate characteristic crack width, following a method such as 26
Eurocode EN 2 1992-1-1 (see section 2.5 in this TN). 27
Either a proprietary or one of several commercially available FE programs can be used for performing this 28
calculation. A few of more widely used non-linear FE programs available in the United States include ANSYS1, 29
ABACUS2, ADINA 3 and NX NASTRAN4. There are also many proprietary FE programs that have been 30
designed specifically to consider the cracking problem for reinforced concrete containment structures. 31
32
2.3.2 SimplifiedFE Analysis 33
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 9 11 / 16 / 2011 (2nd ballot)
Simplified FE analysis is usually used only in the preliminary design. Two possible approaches include: 1
a) Reduced-Stiffness / Cracked-Section Approach: The calculation is performed using a linear finite element 2
analysis where the reduction in stiffness due to cracking is considered. 3
b) Moment-Curvature Approach: The moment curvature properties are obtained using a concrete section 4
analysis by implementing in conjunction with: 5
• non-linear stress-strain material properties, and 6
• a non-linear shell formulation that accounts for the cracking induced stiffness redistribution. 7
8
2.3.3 Mesh Type and Size 9
The linear or non-linear FE model will usually be axisymmetric or a 3D model of the containment for 10
consideration of the general case of a symmetric RLG spill loads and a separate model for consideration of the 11
RLG spill case where non-axisymmetric discontinuities are considered. 12
13
Typically, the structural model contains a fine-mesh or a high density of solution points. The model includes the 14
base slab, foundation springs, containment wall, roof structure and local discontinuities, such as the prestressing 15
buttresses. Liners should be included if they are considered as structural members. 16
17
A more detailed substructure model of the region above the TCP anchorage might be considered in order to 18
reduce the computational demand, provided it can be demonstrated that the boundary conditions and loadings 19
correctly represent the global model. 20
21
The reinforcing and prestressing steel should may also be modeled and the prestressing forces applied as part of 22
the loading or construction sequence. 23
24
2.3.4 Loading 25
The RLG spill case should include hydrostatic pressure from the RLG fluid in the annular space. Dead load, live 26
load and steady state temperatures coincident prior to the RLG spill, shall be applied prior application of the 27
temperature transients. 28
29
30
Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite 31
difference solution. The thermal model used for determining nodal temperatures This thermal model is also a 32
high density model which should include concrete foundation, soil thermal boundary condition, walls, roof and 33
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 10 11 / 16 / 2011 (2nd ballot)
outside or inside ambient temperature boundary conditions. This model should also include the base slab 1
insulation and the thermal corner protection insulation. 2
3
2.3.5 Thermal Analysis 4
The heat transfer analyses should consider both maximum (95th percentile) and minimum (5th percentile) ambient 5
temperatures. The RLG spill is applied internally to the containment y. The RLG spill load case should also 6
include the vapor temperature generated from the spill above the liquid level. Nodal temperature time histories 7
are computed and mapped to the structural finite element model. The concrete wall internal temperatures from 8
the thermal model are also typically used for selection and placement of reinforcement complying with the 9
requirements of ACI 376. 10
11
The RLG hydrostatic pressure and temperature time histories are applied gradually and the iterative solution 12
computes concrete stresses and strains, crack locations and reinforcing stresses. 13
14
15
2.4—Material Constitutive Models 16
17
2.4.1 Concrete Constitutive Model 18
Recognized concrete constitutive models should be used in the analysis. Examples include material models 19
described by Eurocode 25 and shown in the Figure 2.1 below. The concrete constitutive model should also 20
account for reduction in tensile stiffness after cracking of concrete including the effects of tension stiffening. 21
22
Figure 2.1: Stress-Strain Diagram for Uniaxial Compression from Eurocode EN 2 1992-1-1 23
24
The σc – εc material relationship shown in Figure 2.1 is taken from Eurocode EN 2 Part 1, 4.2.1.3.1 (4.1). 25
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 11 11 / 16 / 2011 (2nd ballot)
1
For short term loading the relationship is defined as: 2
σc/fc = (k.n-n2)/[1 + n.(k-2)] (1)
where: 3
fc concrete compressive strength at 28 days (N/mm2) < 0.0 (2)
εcu ultimate strain < 0.0 (3)
n = εc/εc1 (both < 0.0) (4)
εc1 = -0.0022 (strain at the peak stress fc) (5)
k = (1.1Ec,nom).εc1/fc (6)
Ec,nom = Ecm/γc (kN/mm2) (7)
γc partial safety factor = 1.5 unless justified by adequate control procedures. (8)
Ecm = 9.5(fc + 8)1/3 (Ecm in kN/mm2; fc in N/mm2) (9)
4
The tension side of the fc - εc material relationship may be taken as: 5
σc = Ecmεc (N/mm2) for σc < fctm (10)
σc = 0 for σc > or = fctm (11)
where: 6
fctm = 0.30fc2/3 (N/mm2) (13)
7
Tension softening is usually introduced following rupture of the concrete in order to provide for numerical 8
stability in the solution. 9
10
2.4.2 Steel Constitutive Models 11
Figure 2.2 shows a typical uniaxial stress strain curve for reinforcing steel and Figure 2.3 a typical uniaxial stress-12
strain curve for prestressing steel. 13
14
Figure 2.2: Typical Uniaxial Stress-Strain Curve for
Reinforcing Steel from Eurocode EN 2 1992-1-1
Figure 2.3: Typical Uniaxial Stress-Strain Curve for
Prestressing Steel from Eurocode EN 2 1992-1-1
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 12 11 / 16 / 2011 (2nd ballot)
1
2
Other concrete and steel constitutive models may be used provided it can be demonstrated that these models 3
accurately characterize material behavior. 4
5
2.4.3 Selection of Material Parameter Values 6
For the RLG spill case, it is critical that cryogenic liquid be prevented from migrating behind the TCP, and 7
conservative assumptions should be used when selecting material properties. 8
9
2.4.3.1 - Compressive Response 10
It should be noted that the extent of the compression zone is not as critical as the size and extent of the cracks. 11
Therefore, the use of the mean compressive concrete strength is adequate for crack width calculations. The mean 12
modulus of elasticity of the reinforcing and prestressing steel and concrete is also considered adequate. 13
14
2.4.3.2 - Tensile Properties 15
For tension properties, the minimum yield strength of the reinforcing should be considered to maximize the crack 16
width. Also, if tensile strength of the concrete is considered, the analysis should evaluate the 95th and 5th 17
percentile concrete tensile strength limits. A more conservative approach would be to consider no tensile capacity 18
of the concrete in the analysis. 19
20
2.4.3.3 - Temperature Effects on Material Properties 21
Improved material properties at low temperature, should not be used unless adequate cryogenic testing has been 22
carried out to confirm these material properties. The variation of the mean coefficient of thermal expansion with 23
temperature should also be considered in the solution. 24
25
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 13 11 / 16 / 2011 (2nd ballot)
2.5—Crack Width Calculations 1
The Code suggests that Eurocode EN 2 Part 1 4.4.2.4, (4.80) be the basis for calculation of crack widths. In this 2
approach crack width is determined from steel strains using the following relationship: 3
wk = βsrmεsm (14)
where wk is the 95th percentile crack width, εsm is the mean steel strain, srm is the average final crack spacing and β 4
is a design value that can be taken as: 5
• 1.7 for load induced cracking and for restraint cracking in section with minimum dimension in excess of 800 6
mm, or 7
• 1.3 for restraint cracking in sections with a minimum dimension depth, breadth or thickness, (whichever is the 8
lesser) of 300 mm or less. 9
10
The average final crack spacing, srm, is computed from Eurocode 2 Part 1, 4.4.2.4 (4.82) as: 11
srm = 50 + 0.25k1kk2φ/ρr (15)
where: 12
φ is the barsize or average bar size in mm (16)
k1 = 0.8 for high bond bars and 1.6 for plain bars (17)
k = 0.8 for tensile stresses that are due to intrinsic deformations (18)
k2 is a coefficient which accounts for the form of the strain distribution and is between
0.5 for bending and 1.0 for pure tension.
(19)
ρr is the effective reinforcing ratio, As/Ac,eff, where As is the area of reinforcement
contained within the effective tension area, Ac,eff
(20)
13
The mean strain value, εsm, should be computed directly using the non-linear finite element model and considering 14
all loads existing at the time of cracking. More specifically, the mean strain is obtained by averaging calculated 15
strain over the length of steel that has exceeded the yield limit. In other words, for a single piece of reinforcing 16
steel that has exceeded yield, εsm would be computed as the integrated strain over the length of the plastic zone of 17
the reinforcing divided by the length of the plastic zone. 18
19
REFERNCES 20
1. ANSYS Inc., Canonsburg, PA 21
2. ABACUS, Inc., Providence, RI 22
3. ADINA R & D, Inc., Watertown, MA 23
4. Siemens PLM Software, Plano TX 24
5. EUROCODE 2 Design of concrete structures – Part 1 General rules and rules for buildings 25
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 14 11 / 16 / 2011 (2nd ballot)
Appendix A: ACI 376 Code TCP Requirements 1
2
CHAPTER 2—NOTATION AND TERMINOLOGY
thermal corner protection (TCP)—insulated and liquid tight system to protect the outer
tank from thermal shock.
calculated crack width—crack width calculated using a concrete constitutive model
defined in 8.1.1.7.
CHAPTER 6—MINIMUM PERFORMANCE REQUIREMENTS
6.3.2—Under spill conditions, the concrete above the thermal corner protection (TCP)
should remain liquid tight, based upon minimum depths of compression and
precompression.
6.3.4—Calculated crack widths should be considered at TCP embedment when cracking
would result in liquid product migrating behind the TCP and compromising its
effectiveness.
The embedment zone should extend a minimum of two times the wall thickness above the
TCP anchorage. Calculated crack widths should not exceed 0.008 in. within the TCP
embedment
zone.
CHAPTER 8—ANALYSIS & DESIGN
8.1.1.7—Cracking and tension stiffening
should be included by appropriate
modification of the material stress strain
relationship or by the use of finite elements
that have the capability of cracking under
R8.1.1.7—The Eurocode 2 is recommended
for determining calculated crack widths. In
this case, the calculated crack widths are
characteristic and not mean calculated crack
widths.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 15 11 / 16 / 2011 (2nd ballot)
tension, and crushing under compression as
well as the ability to include reinforcing
steel.
Unless otherwise specified, the concrete
constitutive mode from European Code
should be used for determining calculated
crack widths.
Extensive field experience with liquid
retaining and offshore concrete structures
has demonstrated that satisfactory liquid
tightness and liquid retaining performance
can be achieved by imposing calculated
crack width limits.
However, it must be noted that calculated
crack width represents an average numerical
value that is not directly equivalent to
calculated crack width measured in the field.
Due to the non-homogeneous nature of
concrete, calculated crack width values
measured in the field will vary from
calculated values, and therefore they cannot
be directly compared to calculated crack
widths.
1
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 16 11 / 16 / 2011 (2nd ballot)
1
2
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 1 11 / 16 / 2011 (2nd ballot)
ACI 376 Technical Note on 1
Design and Analysis of the TCP Embedment Zone 2
3
Reported by ACI Committee 376 4
5
Concrete Structures for Refrigerated Liquefied Gas Containment 6
7
* Contributing Member 8
9
INTRODUCTION 10
ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner 11
Protection (TCP) embedment zone. The purpose of this Technical Note is to provide further guidance 12
for (a) design and analysis of theTCP anchorage and (b) liquid-tightness analysis in the TCP embedment 13
zone (i.e., crack width calculations). The document therefore consists of two parts: 14
15
1. Part 1 – Detailing & Construction Issues: TCP detailing and related design issues are presented in 16
the first part of this document 17
18
Neven Krstulovic-Opara*
Chair
Piotr D. Moncarz
Secretary
Junius Allen
Thomas A. Ballard*
Dale Berner
Mike S. Brannan
Hamish Douglas*
Jeffrey Garrison*
Charles S. Hanskat
Alan D. Hatfield
Humayun Hashmi
Kare Hjorteset
George C. Hoff*
Richard Hoffmann
John Holleyoak
Joseph M. Hoptay*
Thomas R. Howe
Dajiu Jiang
Jameel U. Khalifa
Nicholas A. Legatos
Praveen K. Malhotra
Keith A. Mash*
Stephen W. Meier
Robert W. Nussmeier
Rolf P. Pawski*
Ramanujam S. Rajan
William E. Rushing
Robert W. Sward
Eric S. Thompson
Sheng-Chi Wu
Deleted: Thermal Corner Protection Design & Crack Analysis
Comment [LE1]: 001 Brannan part 1 Revise title to “Design and Analysis of the TCP Embedment Zone.” Monday 3-19: (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO) 002 Pawski Revise title to read “Liquid tightness Anaysis at the TCP.” Saturday 17 - (8/8) Brannan, Ballard, Hoptay, Howe, Juang, NKO, Pawski, Wu Note superceded by Monday vote.
Comment [LE2]: 003 Hoff comment not addressed. “Useful but seems to be a little bit too long for a TechNote”
Comment [LE3]: 004 Mash comment not addressed. “Comments included in document. There are couple of blind spots which we ought to address via telecon”
Comment [LE4]: 005 Pawski withdrawn Revisit sugested organization at time of final editing. (Sunday 3-18: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE5]: 001 – Brannan part 2. Page 1 lines 11-14. Revise to read as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Deleted: document
Deleted: on
Deleted: detailing
Deleted: TCP
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 2 11 / 16 / 2011 (2nd ballot)
2. Part 2 – Crack Width for Liquid Tightness: One of the key TCP-performance criteria is related to 1
assuring adequate liquid tightness during a spill condition. ACI 376 Code specifies liquid tightness 2
limits in terms of limiting concrete crack widths. The liquid tightness / crack width analysis 3
procedure is presented in the second part of this document, followed by an example outlining 4
proposed analysis steps that would meet ACI 376 Code requirements. 5
6
Although the code and this TN do not explicitly define leak tightness criteria for the anchorage and 7
embeddment, the design and construction of these components should be carried out with the clear 8
objective of protecting the corner joint from product temperatures. 9
10
Comment [LE6]: Part of Ref. 001: T.Ballard negative . Draft of new paragraph for committee consideration agreed to at Minneapolis – 2013.04.13.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 3 11 / 16 / 2011 (2nd ballot)
CONTENTS 1
2
INTRODUCTION 3
4
CHAPTER 1 ———— TCP DESIGN 5
1.1—General 6
1.2—Embedment Plate and Anchorage 7
8
CHAPTER 2 ———— LIQUID TIGHTNESS AND CRACK WIDTH ANALYSIS 9
2.1—General 10
2.2—Analysis Procedure 11
2.3—Numerical Model 12
2.4—Material Constitutive Models 13
2.5—Crack Width Calculations 14
15
APENDICES 16
17
APENDIX A ———— ACI 376 TCP CODE ERQUIREMENTS 18
19
REFERENCES 20
21
Deleted: Anchor Studs
Comment [LE7]: Part of Ref. no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 4 11 / 16 / 2011 (2nd ballot)
CHAPTER 1 – TCP Design 1
2
a) b)
3
Figure 1.1: Thermal Corner Protection (TCP) Detail 4
5
1.1—General 6
The thermal corner protection (TCP) is an insulated and liquid tight system located at the bottom of the outer 7
secondary concrete wall, as shown in Figure 1.1 a. The primary function of TCP is to protect the already highly 8
stressed wall to slab joint from additional thermal loads during spill conditions. The TCP is designed to provide 9
both (a) a liquid and (b) a thermal barrier at the wall to slab joint, thus protecting the joint from exposure to 10
cryogenic temperatures during a spill condition. 11
12
The TCP is connected to a secondary bottom plate that provides a liquid barrier above the slab, as shown in 13
Figure 1.1 a. The TCP is attached to the concrete wall through an embedment plate located at the top of the TCP, 14
as shown in Figure 1.1 b. During the spill condition, the concrete wall above the TCP, the TCP and TCP 15
embedment will be subjected to significant thermal and mechanical loads. The TCP embedment should be 16
designed to remain functional and in place during the spill condition. 17
Comment [LE8]: 006 Wu Comment is “Need to include the secondary bottom plate in the model.” On Figure 1a add a detail circle to identify where Figure 1b is located.
Comment [LE9]: Part of 001 Ballard negative : I believe the embedment zone should extend at least to the bottom of the TCP plate since migration of cracks in this zone would compromise the leak tightness of the detail.
Comment [LE10]: Part of 021 Hoptay negative 2013 04.13 Minneapolis: annotate sketch to state "2 rows of anchors minimum."
Comment [LE11]: Oliver – editorial Pg 4 line 8: addd "the" as shown. 2013.10.21 Phoenix
Deleted: intact
Comment [LE12]: 007 Mash Commetn is “Suggest replacement of 'intact' with functional.” Agree - (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 5 11 / 16 / 2011 (2nd ballot)
1
The concrete wall above the TCP, directly exposed to spilled product, should remain liquid tight and substantially 2
vapor tight during the spill condition. This is assured by maintaining a compression zone in the wall exposed to 3
the spill and by limiting crack width on the inside face of the wall in the TCP embedment zone plate during a spill. 4
5
The scope of this section is to provide guidelines and best practices for the detailing of the TCP region, i.e., the 6
TCP, the TCP embedment plate and TCP embedment plate anchorage to the outer concrete wall. Information is 7
provided for the evaluation of the embedment plate, design of anchors and attachment to the concrete wall, and 8
for the evaluation of cracking in the embedment zone. 9
10
1.2—Embedment Plate and Anchors 11
The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both 12
(a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition including SSEAFT. 13
The TCP design consists of the following steps: 14
15
1.2.1 - STEP 1: TCP Load Definition 16
• Finite element analyses are performed first to determine forces resulting from thermal gradients applied to the 17
TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the 18
embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, 19
hydrostatic pressure and hydrodynamic pressure due to seismic aftershock (SSEAFT). Initial temperatures and 20
conditions should be selected so as to maximize the demand under consideration. For instance for the design 21
of the anchors the critical condition is likely to be warm wall (summer) a cold thermal shock to the 22
embedment, thereby creating maximum strain across the section. 23
• Various spill levels should be considered to determine the most severe effect on the embedment and concrete 24
wall. This should include a spill level located just below the top of the TCP which will place the largest 25
temperature differential between the TCP and the concrete. A minimum of three levels should be considered 26
for spill levels above the TCP, 1) at top of the TCP embedment zone, 2) at mid-height, and 3) at full spill 27
level. 28
• The analysis should be based on both steady state and transient conditions, as specified in ACI 376 Code section 29
8.4.8. R8.4.8 specifically indicates that during transient conditions an embedment such as the TCP will frequently 30
experience the greatest self-straining forces. 31
32
1.2.2 - STEP 2: Embedment Plate Design 33
• The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall. 34
Comment [LE13]: 009 Hoptay Withdrawn
Comment [LE14]: 2013.04.13 Minneapolis – Pg 5 line 2 change "liquid" to "liquid tight."
Comment [LE15]: 008 Mash Response: “Limiting values are covered elsewhere and do not need to be repeated here.”Revise to read for clarity as shown. (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
Deleted: cracking
Comment [LE16]: 011 Mash Page 5 line 4 - no action, included with response 010
Deleted:
Deleted: the vicinity of
Deleted: the anchor studs
Comment [LE17]: Part of Ref. no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
Deleted: Material selection and material ... [1]
Comment [LE18]: 010 Hoptay Delete last sentence. ... [2]
Deleted:
Deleted: Anchor Studs
Comment [LE19]: Part of Ref no. 021 - ... [3]
Comment [LE20]: 013 Wu ... [4]
Comment [LE21]: 014 Mash ... [5]
Deleted: is
Comment [LE22]: 015 Mash
Comment [LE23]: 016 Wu ... [6]
Deleted: Starting
Comment [LE24]: 2013.04.13 Minneapolis. ... [7]
Deleted: and
Deleted: shocking
Deleted: embed
Deleted: . Whereby
Deleted: straining
Deleted: spill levels
Deleted: wall as well as various
Deleted: up to the
Comment [LE25]: 017 and 018 Mash ... [8]
Comment [LE26]: 019 Mash. ... [9]
Comment [LE27]: 020 Mash negative - ... [10]
Deleted: or by other suitable means (e.g., ???)
Deleted: Anchor bolts (studs) should be placed in ... [11]
Comment [LE28]: 020 Hoptay negative - ... [12]
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 6 11 / 16 / 2011 (2nd ballot)
• The embedment plate should be anchored with a minimum of two rows of circumferential anchors. The 1
spacing between anchors has significant impact on the TCP embedment performance and thus should be 2
considered in design. 3
• Embedment plate and mechanical anchor material as well as the TCP material should be suitable for the 4
product temperature. 5
• Allowable stresses i.e., material selection and material requirements used in the design of the embedment 6
plates, may be selected in accordance with API 620. 7
• Anchor spacings should be selected so as to be multiples of the bar spacing to enable a clash-free design. 8
9
1.2.3 - STEP 3: Anchorage Design 10
The mechanical anchorage (anchors bolts or studs) and concrete at the anchor location should meet the 11
requirement for anchoring to the concrete wall defined in the ACI 350 Appendix D. 12
13
1.2.4 - STEP 4: Li quid Tightness 14
Liquid tightness at the embedment plate should be considered in the details and design of the anchorage as 15
defined by the owner. 16
17
Note - consesus at 2013.10.21 Phoenix meeting was new "1.2.4 Step 4" is not needed and
should be deleted in its entirety. Shown for information and is to be deleted.
Deleted: When the embedment
Deleted: is
Deleted: circumferential studs,
Deleted: studs
Deleted: should be used to anchor the embedment plate
Deleted: mechanical anchors (studs) should be limited to ensure that the axial, bending and shear stresses in the embedment plate are within the allowable stresses
Comment [LE29]: 021 Mash negative - resolved Comment is “When? Embedment must be anchored with studs?” Revise as shown, and consider further discussion in future TN. Tues 3-20: (5/5) Garrison, Ballard, Pawski, Brannan, NKO 021 Hoptay negative - resolved – addressed here & Fig. 1.1(b)
Comment [LE30]: 022 Mash Comment is “Consider use of ACI 349? More stringent with respect to anchors.” Non-persuasive. Tues 3-20: (4/4) Garrison, Ballard, Pawski, Brannan
Comment [NKO31]: 026 Mash Non-persuasive, but edit bullet point as shown. Tuesday 3-20: (5/5) Garrison, Ballard, Pawski, Brannan, NKO
Deleted: Anchor Bolt
Deleted: (
Comment [LE32]: 023 Mash Comment is “Consider use of ACI 349? More stringent with respect to anchors.” Non-persuasive. . Discussed March 19 and decided that ACI 350 is appropriate. Also, there does not appear to be any difference between ACI 350 and ACI 349 on this topic; Garrison to verify. Tues 3-20: (4/4) Garrison, Ballard, Pawski, Brannan.
Deleted: <#>The steel strength of the anchor in tension should be as per ACI 350 section D.5.1.
Comment [NKO33]: 024 Hoptay Withdrawn, already addressed.
Deleted: <#>¶<#>The concrete breakout strength of the anchor in tension should be checked per ACI 350 section D.5.2.¶<#>The pullout strength of the anchor in tension should be checked per ACI 350 section D.5.3.¶<#>The steel strength of the anchor in shear should be checked per ACI 350 section D.6.1.¶... [13]
Comment [LE34]: 027 Wu Comment is to add bullet point to read “In moderate or high seismic site, the design strength of anchors should be reduced to 75% of the design strength per Section D.3.3.3.” Withdrawn, Monday 3-19..
Comment [LE35]: 025 Wu Revise 1.2.3 as shown and as new section 1.2.4 as shown. ... [14]
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 7 11 / 16 / 2011 (2nd ballot)
CHAPTER 2 – PART 2: Liquid Tightness and Crack Width Analysis 1
2
2.1—General 3
During the spill condition, the secondary concrete wall will be subjected to high large forces due to mechanical 4
loads and thermal effects that will lead to significant wall cracking. Integrity of the concrete wall must be 5
maintained. As specified in the ACI 376 Code, the wall should remain liquid and substantially vapor tight. More 6
specifically: 7
1) ACI 376 section 6.3.2: “Unless a leak-tight membrane/liner has been used, a minimum portion of the concrete 8
should remain in compression in accordance with the following: 9
a) A compressive zone of either 10% of the section thickness or 3.5 in., whichever is greater shall be provided; and 10
b) A minimum average compressive stress within the compressive zone of 145 lb/in2 should be maintained.” 11
12
2) ACI 376 section 6.3.3: “Calculated crack widths should be considered at TCP embedment when cracking would 13
result in liquid product migrating behind the TCP and compromising its effectiveness. The embedment zone should 14
extend a minimum of two times the wall thickness above the TCP anchorage. Calculated crack widths should not 15
exceed 0.008 in. within the TCP embedment zone. Recommendations for crack width calculations are provided in 16
8.1.1.8.” 17
18
3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean 19
crack widths. 20
21
Non-linear finite element analysis should be performed to ensure that these requirements are met. 22
23
24
2.2—Analysis Procedure 25
The analysis procedure consists of the following steps: 26
27
2.2.1 - STEP 1: Thermal Analysis 28
Thermal analysis is performed based on a thermal model using Finite Element or Finite Difference approach. 29
Steps include: 30
1) Modeling including specific tank geometry and material thermal properties 31
2) Thermal boundary condition definition/application to equilibrium 32
3) Application of RLG spill temperature loads obtained by considering rate of leakage into annular space 33
and exposed to transient temperatures 34
Deleted: When subjected to
Comment [LE36]: 028 Mash negative - resolved
Comment [LE37]: 029 Pawski Comment is mostly superceded by 028 changes, but add “secondary” from Sat 9-17 discussion. (9/9 – see Saturday attendance)
Deleted: loaded with
Deleted: thermally inducedand mechanical forces. These forces
Deleted: During the spill condition, integrity
Comment [LE38]: 028 Hoptay negative - resolved Withdrawn 2013.04.13 Minneapolis
Comment [LE39]: 028 Mash negative - resolved 030 & Comment is “Suggest using nomenclature such as demand as opposed to load.” Agree in part, revise to read as shown Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan
Deleted: 6.3.3
Comment [LE40]: Pawski – editorial. Pg 7 line 8, referenced section does not match published 376-11. Change to 6.3.2. 21-Oct-2013 Phoenix
Deleted: should
Comment [LE41]: 031 Mash Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan
Formatted: Superscript
Deleted: 6.3.4
Comment [LE42]: Pawski – editorial. Pg 7 line 14, referenced section does not match published 376-11. Change to 6.3.3. 21-Oct-2013 Phoenix
Deleted: calculated
Deleted: as per EN 1992-1-1
Comment [LE43]: 032 Mash Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan ... [15]
Deleted:
Comment [LE44]: 033 Jiang Agree, revise as shown. ... [16]
Comment [LE45]: 034 Jiang Agree, revise as shown. ... [17]
Deleted: LNG
Comment [LE46]: 035, 046, 048 Jiang Agree to change LNG to RLG throughout. ... [18]
Deleted: or external fire
Comment [LE47]: 036 Mash ... [19]
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 8 11 / 16 / 2011 (2nd ballot)
1
4) Continue analysis until steady state temperature distribution is obtained 2
5) Repeat for all thermal load cases 3
4
2.2.2 - STEP 2: Structural Analysis 5
Structural Analysis is performed based on the stress model using the Finite Element approach. Steps include 6
1) Modeling 7
2) To establish intiial conditions, apply dead load, prestressing, normal opearting thermal and any other 8
steady state load, then iterate to equilibrium 9
3) Apply RLG spill temperature transients and iterate to equilibrium 10
4) Beginning with the intial condition defined in step 2, compute crack widths at time-steps throughout the 11
transient where reinforcing strains are the greatest . Furthermore, at each time step determine the adequacy of 12
the compression zone. 13
5) Repeat for all thermal load cases 14
15
16
2.3—Numerical Model 17
Calculation of cracking and crack widths for the RLG spill condition shall be performed using a rational 18
engineering analysis. Linear or non-linear finite element (FE) analysis should be used as discussed in 2.3.1 and 19
2.3.2. 20
21
2.3.1 Non-Linear FE Analysis 22
In this case a non-linear finite element program is used by: 23
• Implementing the non-linear material constitutive relationship for concrete and steel, 24
• Carrying out FE analysis to obtainstress/strain contours, and 25
• Performing FE analysis post process to calculate characteristic crack width, following a method such as 26
Eurocode EN 2 1992-1-1 (see section 2.5 in this TN). 27
Either a proprietary or one of several commercially available FE programs can be used for performing this 28
calculation. A few of more widely used non-linear FE programs available in the United States include ANSYS1, 29
ABACUS2, ADINA 3 and NX NASTRAN4. There are also many proprietary FE programs that have been 30
designed specifically to consider the cracking problem for reinforced concrete containment structures. 31
32
2.3.2 SimplifiedFE Analysis 33
Comment [LE48]: 037 Mash & 037 Garrison negative – not resolved Comment is “More explanation required regarding semi coupled analysis (fully coupled not needed)” Respons is that comment is not clear. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Deleted: final temperatures are reached
Comment [LE49]: 037 Jiang Agree, revise as noted. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE50]: 039 Jiang Agree, revise as shown. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE51]: 040 Mash Comment is “Thermal loads from spillage need porting across to structural model.” Response is that no change is needed because the comment is implicit in the step-by-step procedure. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Deleted: Apply
Comment [LE52]: 041 Jiang & 041 Garrison negative – not resolved Agree, revise as shown. ... [20]
Deleted: <#>Check crack widths¶
Comment [LE53]: 042 Pawski – Sat ... [21]
Deleted: LNG
Deleted: Compute
Deleted: times
Deleted: and exceed the material yield stress
Comment [LE54]: 044 & 047 Garrison ... [22]
Deleted: LNG
Deleted: and/or external fire condition
Deleted: Both linear
Comment [LE55]: 049 Mash & Ballard ... [23]
Deleted: in conjunction with
Deleted: non-linear FE material constitutive ... [24]
Deleted: and
Deleted: calculations as per
Comment [LE56]: 050 Jiang ... [25]
Deleted: a
Deleted: . There are several commercially ... [26]
Comment [LE57]: 078 Khalifa: Combine 1st ... [27]
Deleted: Linear
Comment [LE58]: Part of 056 Jiang
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 9 11 / 16 / 2011 (2nd ballot)
Simplified FE analysis is usually used only in the preliminary design. Two possible approaches include: 1
a) Reduced-Stiffness / Cracked-Section Approach: The calculation is performed using a linear finite element 2
analysis where the reduction in stiffness due to cracking is considered. 3
b) Moment-Curvature Approach: The moment curvature properties are obtained using a concrete section 4
analysis by implementing in conjunction with: 5
• non-linear stress-strain material properties, and 6
• a non-linear shell formulation that accounts for the cracking induced stiffness redistribution. 7
8
2.3.3 Mesh Type and Size 9
The linear or non-linear FE model will usually be axisymmetric or a 3D model of the containment for 10
consideration of the general case of a symmetric RLG spill loads and a separate model for consideration of the 11
RLG spill case where non-axisymmetric discontinuities are considered. 12
13
Typically, the structural model contains a fine-mesh or a high density of solution points. The model includes the 14
base slab, foundation springs, containment wall, roof structure and local discontinuities, such as the prestressing 15
buttresses. Liners should be included if they are considered as structural members. 16
17
A more detailed substructure model of the region above the TCP anchorage might be considered in order to 18
reduce the computational demand, provided it can be demonstrated that the boundary conditions and loadings 19
correctly represent the global model. 20
21
The reinforcing and prestressing steel should may also be modeled and the prestressing forces applied as part of 22
the loading or construction sequence. 23
24
2.3.4 Loading 25
The RLG spill case should include hydrostatic pressure from the RLG fluid in the annular space. Dead load, live 26
load and steady state temperatures coincident prior to the RLG spill, shall be applied prior application of the 27
temperature transients. 28
29
30
Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite 31
difference solution. The thermal model used for determining nodal temperatures This thermal model is also a 32
high density model which should include concrete foundation, soil thermal boundary condition, walls, roof and 33
Deleted: Linear
Deleted: However, it should be noted that this is a very time consuming process and is thus usually only used in the preliminary design.
Comment [LE59]: 051 Mash Comment is “We should exercise caution. A number of vendors have historically used this approach and we ought not to say it should not be used.” No change, non-persuasive. Tue 3-20 - (3/3) Pawski, Garrison, Ballard) 053 Jiang Deleted sentence in its entirety (11/11 Wu, Pawski, Hoff, Berner, Howe, Berner, Hjorteset, Garrison, Ballard, DJ, Brannan, NKO) 052 Hoptay Withdrawn Monday March 19. 054 Mash Not addressed, but deletion of the sentence should satisfy comment that “contractors should be able to choose design method.
Deleted: response is
Deleted: program
Deleted: <#>This moment-curvature approach would only be suitable for consideration of the ... [28]
Comment [LE60]: 055 Wu Withdrawn Monday March 19. 056 Jiang Revised as shown. ... [29]
Deleted: small slice
Deleted: LNG
Deleted: larger sector
Comment [LE61]: 077 Khalifa: Pg 9 line 19 add "separate" before "model." ... [30]
Deleted: LNG
Comment [LE62]: 059 Jiang Revise as shown. ... [31]
Comment [LE63]: 060 Jiang No change. ... [32]
Deleted: If the liners are considered as structural members, they
Deleted: too
Comment [LE64]: Pg 9 line 24 Hoff: editorial Change last sentence to read ... [33]
Comment [LE65]: 061 Jiang - withdrawn
Comment [LE66]: 062 Wu ... [34]
Deleted: LNG
Deleted: LNG
Deleted: LNG
Comment [NKO67]: 063 Mash ... [35]
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 10 11 / 16 / 2011 (2nd ballot)
outside or inside ambient temperature boundary conditions. This model should also include the base slab 1
insulation and the thermal corner protection insulation. 2
3
2.3.5 Thermal Analysis 4
The heat transfer analyses should consider both maximum (95th percentile) and minimum (5th percentile) ambient 5
temperatures. The RLG spill is applied internally to the containment y. The RLG spill load case should also 6
include the vapor temperature generated from the spill above the liquid level. Nodal temperature time histories 7
are computed and mapped to the structural finite element model. The concrete wall internal temperatures from 8
the thermal model are also typically used for selection and placement of reinforcement complying with the 9
requirements of ACI 376. 10
11
The RLG hydrostatic pressure and temperature time histories are applied gradually and the iterative solution 12
computes concrete stresses and strains, crack locations and reinforcing stresses. 13
14
15
2.4—Material Constitutive Models 16
17
2.4.1 Concrete Constitutive Model 18
Recognized concrete constitutive models should be used in the analysis. Examples include material models 19
described by Eurocode 25 and shown in the Figure 2.1 below. The concrete constitutive model should also 20
account for reduction in tensile stiffness after cracking of concrete including the effects of tension stiffening. 21
22
Figure 2.1: Stress-Strain Diagram for Uniaxial Compression from Eurocode EN 2 1992-1-1 23
24
The σc – εc material relationship shown in Figure 2.1 is taken from Eurocode EN 2 Part 1, 4.2.1.3.1 (4.1). 25
Deleted: Heat
Comment [LE68]: 064 Pawski Change as shown. (9/9 – see Saturday attendance)
Deleted: LNG
Deleted: and the adjacent tank fire case is applied externall
Deleted: LNG
Comment [LE69]: 065 Mash Comment is “Vapour temperature? This will be affected by convection etc? How is this to be determined.” This is a general comment/question. No new text proposed. Leave as is and consider the issue in the future.
Deleted: to determine the
Deleted: normal (A615), cold-temperature (A706) and cryogenic reinforcing
Comment [LE70]: 066 Hoptay Revise as shown. FUTURE ACTION: revisit use of A706 materials in ACI 376 section 4.7.2. Mon 3-19 -(9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Deleted: LNG
Deleted: shal
Comment [LE71]: Pg 10 line 28 Hoff: editorial Use "should" in non-mandatory TN 21-Oct-2013 Phoenix
Deleted: l
Deleted: linear tension stiffness effects with tension failure or reduction in stiffness at the cracking strain of the concrete
Comment [LE72]: 079 Khalifa: Revise pg 10 line 30 to read: 21-Oct-2013 Phoenix
Comment [LE73]: Typo (see page 8)
Comment [LE74]: 067 Wu Comment is “Need to specify the value for ɛcu = 0.3%” Insert in Figure 7 if editing is possible.
Comment [LE75]: Typo
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 11 11 / 16 / 2011 (2nd ballot)
1
For short term loading the relationship is defined as: 2
σc/fc = (k.n-n2)/[1 + n.(k-2)] (1)
where: 3
fc concrete compressive strength at 28 days (N/mm2) < 0.0 (2)
εcu ultimate strain < 0.0 (3)
n = εc/εc1 (both < 0.0) (4)
εc1 = -0.0022 (strain at the peak stress fc) (5)
k = (1.1Ec,nom).εc1/fc (6)
Ec,nom = Ecm/γc (kN/mm2) (7)
γc partial safety factor = 1.5 unless justified by adequate control procedures. (8)
Ecm = 9.5(fc + 8)1/3 (Ecm in kN/mm2; fc in N/mm2) (9)
4
The tension side of the fc - εc material relationship may be taken as: 5
σc = Ecmεc (N/mm2) for σc < fctm (10)
σc = 0 for σc > or = fctm (11)
where: 6
fctm = 0.30fc2/3 (N/mm2) (13)
7
Tension softening is usually introduced following rupture of the concrete in order to provide for numerical 8
stability in the solution. 9
10
2.4.2 Steel Constitutive Models 11
Figure 2.2 shows a typical uniaxial stress strain curve for reinforcing steel and Figure 2.3 a typical uniaxial stress-12
strain curve for prestressing steel. 13
14
Figure 2.2: Typical Uniaxial Stress-Strain Curve for
Reinforcing Steel from Eurocode EN 2 1992-1-1
Figure 2.3: Typical Uniaxial Stress-Strain Curve for
Prestressing Steel from Eurocode EN 2 1992-1-1
Comment [LE76]: 068 Pawski - withdrawn Add a tension “tail” to the figure. (Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
Deleted: c – c
Comment [LE77]: Pg 11 line 7 Hoff & Widianto: editorial Stress symbols are missing 21-Oct-2013 Phoenix
Deleted: In reality, the tension
Comment [LE78]: 069 Pawski - withdrawn Editorial, change as noted. (Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE79]: 070 Wu Comment is “Need to specify the limiting ultimate steel strain, ɛu.
(Note that the ultimate strains for steel are not discussed in the Code. Committee should discuss, and set the allowable limits. ) CONSIDER FOR FUTURE ACTION
Comment [LE80]: Typo
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 12 11 / 16 / 2011 (2nd ballot)
1
2
Other concrete and steel constitutive models may be used provided it can be demonstrated that these models 3
accurately characterize material behavior. 4
5
2.4.3 Selection of Material Parameter Values 6
For the RLG spill case, it is critical that cryogenic liquid be prevented from migrating behind the TCP, and 7
conservative assumptions should be used when selecting material properties. 8
9
2.4.3.1 - Compressive Response 10
It should be noted that the extent of the compression zone is not as critical as the size and extent of the cracks. 11
Therefore, the use of the mean compressive concrete strength is adequate for crack width calculations. The mean 12
modulus of elasticity of the reinforcing and prestressing steel and concrete is also considered adequate. 13
14
2.4.3.2 - Tensile Properties 15
For tension properties, the minimum yield strength of the reinforcing should be considered to maximize the crack 16
width. Also, if tensile strength of the concrete is considered, the analysis should evaluate the 95th and 5th 17
percentile concrete tensile strength limits. A more conservative approach would be to consider no tensile capacity 18
of the concrete in the analysis. 19
20
2.4.3.3 - Temperature Effects on Material Properties 21
Improved material properties at low temperature, should not be used unless adequate cryogenic testing has been 22
carried out to confirm these material properties. The variation of the mean coefficient of thermal expansion with 23
temperature should also be considered in the solution. 24
25
Deleted: Since for
Comment [LE81]: Pg 12 lines 10 & 11 Hoff: editorial. Change to read 21-Oct-2013 Phoenix
Deleted: LNG
Comment [LE82]: 072 Mash Comment is “Need to look into this area in more detail and will advise through discussion.” This is a general comment.. No new text proposed and no additional input provided sine the last ballot. Leave as is and consider the issue in the future.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 13 11 / 16 / 2011 (2nd ballot)
2.5—Crack Width Calculations 1
The Code suggests that Eurocode EN 2 Part 1 4.4.2.4, (4.80) be the basis for calculation of crack widths. In this 2
approach crack width is determined from steel strains using the following relationship: 3
wk = βsrmεsm (14)
where wk is the 95th percentile crack width, εsm is the mean steel strain, srm is the average final crack spacing and β 4
is a design value that can be taken as: 5
• 1.7 for load induced cracking and for restraint cracking in section with minimum dimension in excess of 800 6
mm, or 7
• 1.3 for restraint cracking in sections with a minimum dimension depth, breadth or thickness, (whichever is the 8
lesser) of 300 mm or less. 9
10
The average final crack spacing, srm, is computed from Eurocode 2 Part 1, 4.4.2.4 (4.82) as: 11
srm = 50 + 0.25k1kk2φ/ρr (15)
where: 12
φ is the barsize or average bar size in mm (16)
k1 = 0.8 for high bond bars and 1.6 for plain bars (17)
k = 0.8 for tensile stresses that are due to intrinsic deformations (18)
k2 is a coefficient which accounts for the form of the strain distribution and is between
0.5 for bending and 1.0 for pure tension.
(19)
ρr is the effective reinforcing ratio, As/Ac,eff, where As is the area of reinforcement
contained within the effective tension area, Ac,eff
(20)
13
The mean strain value, εsm, should be computed directly using the non-linear finite element model and considering 14
all loads existing at the time of cracking. More specifically, the mean strain is obtained by averaging calculated 15
strain over the length of steel that has exceeded the yield limit. In other words, for a single piece of reinforcing 16
steel that has exceeded yield, εsm would be computed as the integrated strain over the length of the plastic zone of 17
the reinforcing divided by the length of the plastic zone. 18
19
REFERNCES 20
1. ANSYS Inc., Canonsburg, PA 21
2. ABACUS, Inc., Providence, RI 22
3. ADINA R & D, Inc., Watertown, MA 23
4. Siemens PLM Software, Plano TX 24
5. EUROCODE 2 Design of concrete structures – Part 1 General rules and rules for buildings 25
Comment [LE83]: 071 Wu Monday march 19 withdrawn because 2004 edition equations will be used. 074 Garrison negative and 2012.10.13 Phoenix Wu negative – not addressed . To update equations to 2004 edition.
Comment [LE84]: Typo
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 14 11 / 16 / 2011 (2nd ballot)
Appendix A: ACI 376 Code TCP Requirements 1
2
CHAPTER 2—NOTATION AND TERMINOLOGY
thermal corner protection (TCP)—insulated and liquid tight system to protect the outer
tank from thermal shock.
calculated crack width—crack width calculated using a concrete constitutive model
defined in 8.1.1.7.
CHAPTER 6—MINIMUM PERFORMANCE REQUIREMENTS
6.3.2—Under spill conditions, the concrete above the thermal corner protection (TCP)
should remain liquid tight, based upon minimum depths of compression and
precompression.
6.3.4—Calculated crack widths should be considered at TCP embedment when cracking
would result in liquid product migrating behind the TCP and compromising its
effectiveness.
The embedment zone should extend a minimum of two times the wall thickness above the
TCP anchorage. Calculated crack widths should not exceed 0.008 in. within the TCP
embedment
zone.
CHAPTER 8—ANALYSIS & DESIGN
8.1.1.7—Cracking and tension stiffening
should be included by appropriate
modification of the material stress strain
relationship or by the use of finite elements
that have the capability of cracking under
R8.1.1.7—The Eurocode 2 is recommended
for determining calculated crack widths. In
this case, the calculated crack widths are
characteristic and not mean calculated crack
widths.
Comment [LE85]: 075 Pawski Resolution is: This is an editorial comment. Appendix A is a “copy” of what is in the Code. It is provided for reader’s convenience. Reconcile duplication between 2.1 and Appendix A, such as removing Appendix A
Comment [LE86]: 074 Garrison Response is: 1)Definition of the spill loading is beyond the scope of the current TN and will thus be addressed in a separate document defining LNG spill conditions. 2)Update and change the model to the latest 2004 edition of the Eurocode,
(Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Brnnan, Hjorteset, Hoptay, Garrison, Ballard, NKO)
Deleted: 0.004
Comment [LE87]: 073 Wu Comment is “Change the crack width of 0.004 in to 0.008 in.” Section 6.3.4 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 15 11 / 16 / 2011 (2nd ballot)
tension, and crushing under compression as
well as the ability to include reinforcing
steel.
Unless otherwise specified, the concrete
constitutive mode from European Code
should be used for determining calculated
crack widths.
Extensive field experience with liquid
retaining and offshore concrete structures
has demonstrated that satisfactory liquid
tightness and liquid retaining performance
can be achieved by imposing calculated
crack width limits.
However, it must be noted that calculated
crack width represents an average numerical
value that is not directly equivalent to
calculated crack width measured in the field.
Due to the non-homogeneous nature of
concrete, calculated crack width values
measured in the field will vary from
calculated values, and therefore they cannot
be directly compared to calculated crack
widths.
1
Comment [LE88]: 076 Thompson Comment is “Remove the last sentence from the Code Commentary: “Due to the non-homogeneous nature of concrete, calculated crack width values measured in the field will vary from calculated values, and therefore they cannot be directly compared to calculated crack widths.”” Section R8.1.1.7 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 16 11 / 16 / 2011 (2nd ballot)
1
2
Page 5: [1] Deleted rpawski 3/31/2012 1:57:00 PM
Material selection and material requirements used in the design of the 9% nickel-steel TCP and secondary
bottom plates may be performed in accordance with API 620.
Page 5: [2] Comment [LE18] rpawski 1/14/2014 3:42:00 PM
010 Hoptay Delete last sentence. 012 Hoptay Comment found non-persuasive. Dealt with already elsewhere by deleting last sentence (Hoptay comment). (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
Page 5: [3] Comment [LE19] rpawski 1/14/2014 3:42:00 PM
Part of Ref no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
Page 5: [4] Comment [LE20] rpawski 1/14/2014 3:42:00 PM
013 Wu Agree, revise as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Page 5: [5] Comment [LE21] rpawski 1/14/2014 3:42:00 PM
014 Mash Agree in principle, but this is already addressed by requirement of analysis for thermal gradient. Future TN will define design conditions. (6/6) Garrison, Howe, Ballard, Pawski, Hoptay, Wu
Page 5: [6] Comment [LE23] rpawski 1/14/2014 3:42:00 PM
016 Wu Agree, revise as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Page 5: [7] Comment [LE24] rpawski 1/14/2014 3:42:00 PM
2013.04.13 Minneapolis. Revise last three sentences as shown.
Page 5: [8] Comment [LE25] rpawski 1/14/2014 3:42:00 PM
017 and 018 Mash negative . Should be 5 locations, not 3 as shown. Revise as shown. (6/6) Garrison, Howe, Ballard, Pawski, Hoptay, Wu
Page 5: [9] Comment [LE26] rpawski 1/14/2014 3:42:00 PM
019 Mash. Comment is “Suggest inclusion of the words 'in the absence of a defined leak rate all intermediate levels shall be investigated. In practice this may be achieved by running a number spill levels to so as adequately bound the demands. Typically 5 levels may be used dividing the spill height into 4 equal units. In addition levels in close proximity to the TCP must be investigated.” No change. The response will be covered in the future TN on the design basis (DJ comment).
Page 5: [10] Comment [LE27] rpawski 1/14/2014 4:17:00 PM
020 Mash negative - resolved Comment is “Must be achieved through mechanical anchoring.” Agree, revise as shown.
Anchor bolts (studs) should be placed in continuous (circumferential) rows along the concrete wall. •
Page 5: [12] Comment [LE28] rpawski 1/14/2014 4:18:00 PM
020 Hoptay negative - resolved Delete 2nd sentence as it is essentially same as next sentnece. Agree 2013.04.13 Minneapolis.
Page 6: [13] Deleted rpawski 3/31/2012 2:47:00 PM
The concrete breakout strength of the anchor in tension should be checked per ACI 350 section
D.5.2. The pullout strength of the anchor in tension should be checked per ACI 350 section D.5.3. The steel strength of the anchor in shear should be checked per ACI 350 section D.6.1. The concrete breakout strength of the anchor in shear should be checked per ACI 350 section
D.6.2. The concrete pry-out strength of the anchor in shear should be checked per ACI 350 section D.6.3. Interaction of tensile and shear forces should be checked per ACI 350 section D.7.
Page 6: [14] Comment [LE35] rpawski 1/14/2014 3:42:00 PM
025 Wu Revise 1.2.3 as shown and as new section 1.2.4 as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO) 2013.10.21 Phoenix – consensus was new section 1.2.4 is not needed and should be deleted in its entirtety.
Page 7: [15] Comment [LE43] rpawski 1/14/2014 4:33:00 PM
032 Mash Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan 032 Mash, Wu & Garrison negatives – not resolved – Requires discussion as it is not clear what was resolved, if anything.
Page 7: [16] Comment [LE44] rpawski 1/14/2014 3:42:00 PM
033 Jiang Agree, revise as shown. (9/9 Wu, Pawski, Howe, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 7: [17] Comment [LE45] rpawski 1/14/2014 3:42:00 PM
034 Jiang Agree, revise as shown. (10/10 Wu, Pawski, Berner, Howe, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 7: [18] Comment [LE46] rpawski 1/14/2014 3:42:00 PM
035, 046, 048 Jiang Agree to change LNG to RLG throughout. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 7: [19] Comment [LE47] rpawski 1/14/2014 3:42:00 PM
036 Mash Comment is “This needs careful though to ensure alignment and is the key.
Does the analyst knock out the insulation in the 'wet' zone and apply a rapid temperature gradient? or do something more sensible.” Response is no change, this is topic of a future TN for RLG spill load defintion. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Agree, revise as shown. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 8: [21] Comment [LE53] rpawski 1/14/2014 3:42:00 PM
042 Pawski – Sat (superceded) 043 Jiang – delete as shown. Sunday 3-18 - (11/11 Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, NKO)
Page 8: [22] Comment [LE54] rpawski 1/14/2014 3:42:00 PM
044 & 047 Garrison negative – not resolved 044 Mash & 047 Jiang - Revise as shown. Tue 3-20 - (3/3) Garrison, Ballard, Pawski & Sun 3-19 - (12/12 Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO) 045 Hoptay – withdrawn
Page 8: [23] Comment [LE55] rpawski 1/14/2014 3:42:00 PM
049 Mash & Ballard negatives – not resolved Agree, revise as shown. Tue 3-20 - (3/3) Pawski, Garrison, Ballard)
Page 8: [24] Deleted rpawski 3/31/2012 5:24:00 PM
non-linear FE material constitutive models •
Page 8: [25] Comment [LE56] rpawski 1/14/2014 3:42:00 PM
050 Jiang Agree, revise as shown. (11/11 Wu, Pawski, Hoff, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 8: [26] Deleted rpawski 1/13/2014 12:06:00 PM
. There are several commercially available FE programs that are adequate
Page 8: [27] Comment [LE57] rpawski 1/14/2014 3:42:00 PM
078 Khalifa: Combine 1st two sentences pg 8 lines 32, 33 to read: 21-Oct-2013 Phoenix
Page 9: [28] Deleted rpawski 3/31/2012 5:42:00 PM
This moment-curvature approach would only be suitable for consideration of the steady state
linear thermal gradient case and should also be used only for preliminary design.
Page 9: [29] Comment [LE60] rpawski 1/14/2014 3:42:00 PM
055 Wu Withdrawn Monday March 19. 056 Jiang Revised as shown. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO) 057 & 058 Mash not addressed. Leave as is.
21-Oct-2013 Phoenix
Page 9: [31] Comment [LE62] rpawski 1/14/2014 3:42:00 PM
059 Jiang Revise as shown. (12/12 Wu, Pawski, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 9: [32] Comment [LE63] rpawski 1/14/2014 3:42:00 PM
060 Jiang No change. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Page 9: [33] Comment [LE64] rpawski 1/14/2014 3:42:00 PM
Pg 9 line 24 Hoff: editorial Change last sentence to read 21-Oct-2013 Phoenix
Page 9: [34] Comment [LE66] rpawski 1/14/2014 3:42:00 PM
062 Wu Comment is “Change the word, “may” to “should”, since the reinforcing and pre-stressing steel need to be included in the nonlinear FEM cracking analysis in the liquid spill case.”
Page 9: [35] Comment [NKO67] krstulovic 1/14/2014 3:42:00 PM
063 Mash Comment is “Seems out of place in terms of the flow of the document.” 063 Oliver negative - not addressed
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 1 11 / 16 / 2011 (2nd ballot)
ACI 376 Technical Note on 1
Thermal Corner Protection Design & Crack AnalysisDesign and Analysis 2
of the TCP Embedment Zone 3
4
Reported by ACI Committee 376 5
6
Concrete Structures for Refrigerated Liquefied Gas Containment 7
8
* Contributing Member 9
10
INTRODUCTION 11
ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner 12
Protection (TCP) embedment zone. The purpose of this document Technical Note is to provide further 13
guidance on for (a) design and analysis of theTCP detailing anchorage and (b) TCP liquid-tightness 14
analysis in the TCP embedment zone (i.e., crack width calculations). The document therefore consists 15
of two parts: 16
17
Neven Krstulovic-Opara*
Chair
Piotr D. Moncarz
Secretary
Junius Allen
Thomas A. Ballard*
Dale Berner
Mike S. Brannan
Hamish Douglas*
Jeffrey Garrison*
Charles S. Hanskat
Alan D. Hatfield
Humayun Hashmi
Kare Hjorteset
George C. Hoff*
Richard Hoffmann
John Holleyoak
Joseph M. Hoptay*
Thomas R. Howe
Dajiu Jiang
Jameel U. Khalifa
Nicholas A. Legatos
Praveen K. Malhotra
Keith A. Mash*
Stephen W. Meier
Robert W. Nussmeier
Rolf P. Pawski*
Ramanujam S. Rajan
William E. Rushing
Robert W. Sward
Eric S. Thompson
Sheng-Chi Wu
Comment [LE1]: 001 Brannan part 1 Revise title to “Design and Analysis of the TCP Embedment Zone.” Monday 3-19: (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO) 002 Pawski Revise title to read “Liquid tightness Anaysis at the TCP.” Saturday 17 - (8/8) Brannan, Ballard, Hoptay, Howe, Juang, NKO, Pawski, Wu Note superceded by Monday vote.
Comment [LE2]: 003 Hoff comment not addressed. “Useful but seems to be a little bit too long for a TechNote”
Comment [LE3]: 004 Mash comment not addressed. “Comments included in document. There are couple of blind spots which we ought to address via telecon”
Comment [LE4]: 005 Pawski withdrawn Revisit sugested organization at time of final editing. (Sunday 3-18: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE5]: 001 – Brannan part 2. Page 1 lines 11-14. Revise to read as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 2 11 / 16 / 2011 (2nd ballot)
1. Part 1 – Detailing & Construction Issues: TCP detailing and related design issues are presented in 1
the first part of this document 2
3
2. Part 2 – Crack Width for Liquid Tightness: One of the key TCP-performance criteria is related to 4
assuring adequate liquid tightness during a spill condition. ACI 376 Code specifies liquid tightness 5
limits in terms of limiting concrete crack widths. The liquid tightness / crack width analysis 6
procedure is presented in the second part of this document, followed by an example outlining 7
proposed analysis steps that would meet ACI 376 Code requirements. 8
9
Although the code and this TN do not explicitly define leak tightness criteria for the anchorage and 10
embeddment, the design and construction of these components should be carried out with the clear 11
objective of protecting the corner joint from product temperatures. 12
13
Comment [LE6]: Part of Ref. 001: T.Ballard negative . Draft of new paragraph for committee consideration agreed to at Minneapolis – 2013.04.13.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 3 11 / 16 / 2011 (2nd ballot)
CONTENTS 1
2
INTRODUCTION 3
4
CHAPTER 1 ———— TCP DESIGN 5
1.1—General 6
1.2—Embedment Plate and Anchor StudsAnchorage 7
8
CHAPTER 2 ———— LIQUID TIGHTNESS AND CRACK WIDTH ANALYSIS 9
2.1—General 10
2.2—Analysis Procedure 11
2.3—Numerical Model 12
2.4—Material Constitutive Models 13
2.5—Crack Width Calculations 14
15
APENDICES 16
17
APENDIX A ———— ACI 376 TCP CODE ERQUIREMENTS 18
19
REFERENCES 20
21
Comment [LE7]: Part of Ref. no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 4 11 / 16 / 2011 (2nd ballot)
CHAPTER 1 – TCP Design 1
2
a) b)
3
Figure 1.1: Thermal Corner Protection (TCP) Detail 4
5
1.1—General 6
The thermal corner protection (TCP) is an insulated and liquid tight system located at the bottom of the outer 7
secondary concrete wall, as shown in Figure 1.1 a. The primary function of TCP is to protect the already highly 8
stressed wall to slab joint from additional thermal loads during spill conditions. The TCP is designed to provide 9
both (a) a liquid and (b) a thermal barrier at the wall to slab joint, thus protecting the joint from exposure to 10
cryogenic temperatures during a spill condition. 11
12
The TCP is connected to a secondary bottom plate that provides a liquid barrier above the slab, as shown in 13
Figure 1.1 a. The TCP is attached to the concrete wall through an embedment plate located at the top of the TCP, 14
as shown in Figure 1.1 b. During the spill condition, the concrete wall above the TCP, the TCP and TCP 15
embedment will be subjected to significant thermal and mechanical loads. The TCP embedment should be 16
designed to remain intact functional and in place during the spill condition. 17
Comment [LE8]: 006 Wu Comment is “Need to include the secondary bottom plate in the model.” On Figure 1a add a detail circle to identify where Figure 1b is located.
Comment [LE9]: Part of 001 Ballard negative : I believe the embedment zone should extend at least to the bottom of the TCP plate since migration of cracks in this zone would compromise the leak tightness of the detail.
Comment [LE10]: Part of 021 Hoptay negative 2013 04.13 Minneapolis: annotate sketch to state "2 rows of anchors minimum."
Comment [LE11]: Oliver – editorial Pg 4 line 8: addd "the" as shown. 2013.10.21 Phoenix
Comment [LE12]: 007 Mash Commetn is “Suggest replacement of 'intact' with functional.” Agree - (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 5 11 / 16 / 2011 (2nd ballot)
1
The concrete wall above the TCP, directly exposed to spilled product, should remain liquid tight and substantially 2
vapor tight during the spill condition. This is assured by maintaining a compression zone in the wall exposed to 3
the spill and by limiting cracking crack width on the inside face of the wall in the vicinity of the TCP embedment 4
zone plate during a spill. 5
6
The scope of this section is to provide guidelines and best practices for the detailing of the TCP region, i.e., the 7
TCP, the TCP embedment plate and TCP embedment plate anchorage to the outer concrete wall. Information is 8
provided for the evaluation of the embedment plate, design of the anchor studsanchors and attachment to the 9
concrete wall, and for the evaluation of cracking in the embedment zone. Material selection and material 10
requirements used in the design of the 9% nickel-steel TCP and secondary bottom plates may be performed in 11
accordance with API 620. 12
13
1.2—Embedment Plate and Anchor StudsAnchors 14
The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both 15
(a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition including SSEAFT. 16
The TCP design consists of the following steps: 17
18
1.2.1 - STEP 1: TCP Load Definition 19
• Finite element analyses is are performed first to determine forces resulting from thermal gradients applied to 20
the TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the 21
embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, 22
hydrostatic pressure and hydrodynamic pressure due to seismic aftershock (SSEAFT). Starting Initial 23
temperatures and conditions should be selected so as to maximize the demand under consideration. For 24
instance for the design of the anchors the critical condition is likely to be warm wall (summer) and a cold 25
shocking thermal shock to the embedembedment. Whereby, thereby creating maximum straining strain across 26
the section. 27
• Various spill levels should be considered to determine the most severe effect on the embedment and concrete 28
wall. This should include spill levels a spill level located just below the top of the TCP which will place the 29
largest temperature differential between the TCP and the concrete. wall as well as various A minimum of 30
three levels should be considered for spill levels above the TCP, up to the1) at top of the TCP embedment 31
zone, 2) at mid-height, and 3) at full spill level. 32
Comment [LE13]: 009 Hoptay Withdrawn
Comment [LE14]: 2013.04.13 Minneapolis – Pg 5 line 2 change "liquid" to "liquid tight."
Comment [LE15]: 008 Mash Response: “Limiting values are covered elsewhere and do not need to be repeated here.”Revise to read for clarity as shown. (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
Comment [LE16]: 011 Mash Page 5 line 4 - no action, included with response 010
Comment [LE17]: Part of Ref. no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
Comment [LE18]: 010 Hoptay Delete last sentence. 012 Hoptay Comment found non-persuasive. Dealt with already elsewhere by deleting last sentence (Hoptay comment). (8/8) Garrison, Howe, Hoff, Ballard, Pawski, Brannan, Hoptay, Wu
Comment [LE19]: Part of Ref no. 021 - 2013.04.13 Minneapolis. Edit TN to use "anchors" rather than "bolts" or "studs" throughout.
Comment [LE20]: 013 Wu Agree, revise as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE21]: 014 Mash Agree in principle, but this is already addressed by requirement of analysis for thermal gradient. Future TN will define design conditions. (6/6) Garrison, Howe, Ballard, Pawski, Hoptay, Wu
Comment [LE22]: 015 Mash
Comment [LE23]: 016 Wu Agree, revise as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE24]: 2013.04.13 Minneapolis. Revise last three sentences as shown.
Comment [LE25]: 017 and 018 Mash negative . Should be 5 locations, not 3 as shown. Revise as shown. (6/6) Garrison, Howe, Ballard, Pawski, Hoptay, Wu
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 6 11 / 16 / 2011 (2nd ballot)
• The analysis should be based on both steady state and transient conditions, as specified in ACI 376 Code section 1
8.4.8. R8.4.8 specifically indicates that during transient conditions an embedment such as the TCP will frequently 2
experience the greatest self-straining forces. 3
4
1.2.2 - STEP 2: Embedment Plate Design 5
• The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall or by other 6
suitable means (e.g., ???). Anchor bolts (studs) should be placed in continuous (circumferential) rows along 7
the concrete wall. 8
• When the embedmentThe embedment plate is should be anchored with circumferential studs, a minimum of 9
two rows of circumferential studsanchors should be used to anchor the embedment plate. The spacing 10
between mechanical anchors (studs) should be limited to ensure that the axial, bending and shear stresses in 11
the embedment plate are within the allowable stressesanchors has significant impact on the TCP embedment 12
performance and thus should be considered in design. 13
• Embedment plate and mechanical anchor material as well as the TCP material should be suitable for the 14
product temperature. 15
• Allowable stresses i.e., material selection and material requirements used in the design of the embedment 16
plates, may be selected in accordance with API 620. 17
• Anchor spacings should be selected so as to be multiples of the bar spacing to enable a clash-free design. 18
19
1.2.3 - STEP 3: Anchor BoltAnchorage Design 20
The mechanical anchorage (anchors bolts (or studs) and concrete at the anchor location should meet the 21
requirement for anchoring to the concrete wall defined in the ACI 350 Appendix D. 22
• The steel strength of the anchor in tension should be as per ACI 350 section D.5.1. 23
• The concrete breakout strength of the anchor in tension should be checked per ACI 350 section D.5.2. 24
• The pullout strength of the anchor in tension should be checked per ACI 350 section D.5.3. 25
• The steel strength of the anchor in shear should be checked per ACI 350 section D.6.1. 26
• The concrete breakout strength of the anchor in shear should be checked per ACI 350 section D.6.2. 27
• The concrete pry-out strength of the anchor in shear should be checked per ACI 350 section D.6.3. 28
• Interaction of tensile and shear forces should be checked per ACI 350 section D.7. 29
30
1.2.4 - STEP 4: Li quid Tightness 31
Liquid tightness at the embedment plate should be considered in the details and design of the anchorage as 32
defined by the owner. 33
34
Note - consesus at 2013.10.21 Phoenix meeting was new "1.2.4 Step 4" is not needed and
should be deleted in its entirety. Shown for information and is to be deleted.
Comment [LE26]: 019 Mash. Comment is “Suggest inclusion of the words 'in the absence of a defined leak rate all intermediate levels shall be investigated. In practice this may be achieved by running a number spill levels to so as adequately bound the demands. Typically 5 levels may be used dividing the spill height into 4 equal units. In addition levels in close proximity to the TCP must be investigated.” No change. The response will be covered in the future TN on the design basis (DJ comment).
Comment [LE27]: 020 Mash negative - resolved Comment is “Must be achieved through mechanical anchoring.” Agree, revise as shown. Tues 3-20: (5/5) Garrison, Ballard, Pawski, Brannan, NKO
Comment [LE28]: 020 Hoptay negative - resolved Delete 2nd sentence as it is essentially same as next sentnece. Agree 2013.04.13 Minneapolis.
Comment [LE29]: 021 Mash negative - resolved Comment is “When? Embedment must be anchored with studs?” Revise as shown, and consider further discussion in future TN. Tues 3-20: (5/5) Garrison, Ballard, Pawski, Brannan, NKO 021 Hoptay negative - resolved – addressed here & Fig. 1.1(b)
Comment [LE30]: 022 Mash Comment is “Consider use of ACI 349? More stringent with respect to anchors.” Non-persuasive. Tues 3-20: (4/4) Garrison, Ballard, Pawski, Brannan
Comment [NKO31]: 026 Mash Non-persuasive, but edit bullet point as shown. Tuesday 3-20: (5/5) Garrison, Ballard, Pawski, Brannan, NKO
Comment [LE32]: 023 Mash Comment is “Consider use of ACI 349? More stringent with respect to anchors.” Non-persuasive. . Discussed March 19 and decided that ACI 350 is appropriate. Also, there does not appear to be any difference between ACI 350 and ACI 349 on this topic; Garrison to verify. Tues 3-20: (4/4) Garrison, Ballard, Pawski, Brannan.
Comment [NKO33]: 024 Hoptay Withdrawn, already addressed.
Comment [LE34]: 027 Wu Comment is to add bullet point to read “In moderate or high seismic site, the design strength of anchors should be reduced to 75% of the design strength per Section D.3.3.3.” Withdrawn, Monday 3-19..
Comment [LE35]: 025 Wu Revise 1.2.3 as shown and as new section 1.2.4 as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO) ... [1]
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 7 11 / 16 / 2011 (2nd ballot)
CHAPTER 2 – PART 2: Liquid Tightness and Crack Width Analysis 1
2
2.1—General 3
When subjected toDuring the spill condition, the secondary concrete wall will be loaded withsubjected to high 4
large forces thermally inducedand mechanical forces. These forcesdue to mechanical loads and thermal effects 5
that will lead to significant wall cracking. During the spill condition, integrity Integrity of the concrete wall must 6
be maintained. As specified in the ACI 376 Code, the wall should remain liquid and substantially vapor tight. 7
More specifically: 8
1) ACI 376 section 6.3.36.3.2: “Unless a leak-tight membrane/liner has been used, a minimum portion of the concrete 9
should remain in compression in accordance with the following: 10
a) A compressive zone of either 10% of the section thickness or 3.5 in., whichever is greater should shall be 11
provided; and 12
b) A minimum average compressive stress within the compressive zone of 145 lb/in2 should be maintained.” 13
14
2) ACI 376 section 6.3.46.3.3: “Calculated crack widths should be considered at TCP embedment when cracking 15
would result in liquid product migrating behind the TCP and compromising its effectiveness. The embedment zone 16
should extend a minimum of two times the wall thickness above the TCP anchorage. Calculated crack widths should 17
not exceed 0.008 in. within the TCP embedment zone. Recommendations for crack width calculations are provided in 18
8.1.1.8.” 19
20
3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean 21
calculated crack widths as per EN 1992-1-1. 22
23
Non-linear finite element analysis should be performed to ensure that these requirements are met. 24
25
26
2.2—Analysis Procedure 27
The analysis procedure consists of the following steps: 28
29
2.2.1 - STEP 1: Thermal Analysis 30
Thermal analysis is performed based on a thermal model using Finite Element or Finite Difference approach. 31
Steps include: 32
1) Modeling including specific tank geometry and material thermal properties 33
2) Thermal boundary condition definition/application to equilibrium 34
Comment [LE36]: 028 Mash negative - resolved
Comment [LE37]: 029 Pawski Comment is mostly superceded by 028 changes, but add “secondary” from Sat 9-17 discussion. (9/9 – see Saturday attendance)
Comment [LE38]: 028 Hoptay negative - resolved Withdrawn 2013.04.13 Minneapolis
Comment [LE39]: 028 Mash negative - resolved 030 & Comment is “Suggest using nomenclature such as demand as opposed to load.” Agree in part, revise to read as shown Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan
Comment [LE40]: Pawski – editorial. Pg 7 line 8, referenced section does not match published 376-11. Change to 6.3.2. 21-Oct-2013 Phoenix
Comment [LE41]: 031 Mash Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan
Formatted: Superscript
Comment [LE42]: Pawski – editorial. Pg 7 line 14, referenced section does not match published 376-11. Change to 6.3.3. 21-Oct-2013 Phoenix
Comment [LE43]: 032 Mash Tues 3-20 - (4/4) Garrison, Ballard, Pawski, Brannan 032 Mash, Wu & Garrison negatives – not resolved – Requires discussion as it is not clear what was resolved, if anything.
Comment [LE44]: 033 Jiang Agree, revise as shown. (9/9 Wu, Pawski, Howe, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE45]: 034 Jiang Agree, revise as shown. (10/10 Wu, Pawski, Berner, Howe, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 8 11 / 16 / 2011 (2nd ballot)
3) Application of LNG RLG spill or external fire temperature loads obtained by considering rate of leakage 1
into annular space and exposed to transient temperatures 2
3
4) Continue analysis until steady state final temperatures are reachedtemperature distribution is obtained 4
5) Repeat for all thermal load cases 5
6
2.2.2 - STEP 2: Structural Analysis 7
Structural Analysis is performed based on the stress model using the Finite Element approach. Steps include 8
1) Modeling 9
2) Apply To establish intiial conditions, apply dead load, prestressing, normal opearting thermal and any 10
other steady state load, then iterate to equilibrium 11
3) Check crack widths 12
4)3) Apply LNG RLG spill temperature transients and iterate to equilibrium 13
5)4) Compute Beginning with the intial condition defined in step 2, compute crack widths at times 14
time-steps throughout the transient where reinforcing strains are the greatest and exceed the material yield 15
stress. Furthermore, at each time step determine the adequacy of the compression zone. 16
6)5) Repeat for all thermal load cases 17
18
19
2.3—Numerical Model 20
Calculation of cracking and crack widths for the LNG RLG spill condition and/or external fire condition shall be 21
performed using a rational engineering analysis. Both linearLinear or non-linear finite element (FE) analysis 22
should be used as discussed in 2.3.1 and 2.3.2. 23
24
2.3.1 Non-Linear FE Analysis 25
In this case a non-linear finite element program is used in conjunction withby: 26
• non-linear FE material constitutive modelsImplementing the non-linear material constitutive relationship 27
for concrete and steel, and 28
• Carrying out FE analysis to obtainstress/strain contours, and 29
• Performing FE analysis post process to calculate characteristic crack width, calculations as per following 30
a method such as Eurocode EN 2 1992-1-1 (see section 2.5 in this TN). 31
Either a proprietary or a one of several commercially available FE programs can be used. There are several 32
commercially available FE programs that are adequate for performing this calculation. A few of more widely 33
Comment [LE46]: 035, 046, 048 Jiang Agree to change LNG to RLG throughout. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE47]: 036 Mash Comment is “This needs careful though to ensure alignment and is the key. Does the analyst knock out the insulation in the 'wet' zone and apply a rapid temperature gradient? or do something more sensible.” Response is no change, this is topic of a future TN for RLG spill load defintion. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Comment [LE48]: 037 Mash & 037 Garrison negative – not resolved Comment is “More explanation required regarding semi coupled analysis (fully coupled not needed)” Respons is that comment is not clear. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Comment [LE49]: 037 Jiang Agree, revise as noted. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE50]: 039 Jiang Agree, revise as shown. (11/11 Wu, Pawski, Berner, Howe, Hanskat Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE51]: 040 Mash Comment is “Thermal loads from spillage need porting across to structural model.” Response is that no change is needed because the comment is implicit in the step-by-step procedure. (5/5) Garrison, Ballard, Pawski, Brannan, Hjorteset
Comment [LE52]: 041 Jiang & 041 Garrison negative – not resolved Agree, revise as shown. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE53]: 042 Pawski – Sat (superceded) 043 Jiang – delete as shown. ... [2]
Comment [LE54]: 044 & 047 Garrison negative – not resolved 044 Mash & 047 Jiang - Revise as shown. Tue 3-20 - (3/3) Garrison, Ballard, Pawski ... [3]
Comment [LE55]: 049 Mash & Ballard negatives – not resolved Agree, revise as shown. Tue 3-20 - (3/3) Pawski, Garrison, Ballard)
Comment [LE56]: 050 Jiang Agree, revise as shown. (11/11 Wu, Pawski, Hoff, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE57]: 078 Khalifa: Combine 1st two sentences pg 8 lines 32, 33 to read: 21-Oct-2013 Phoenix
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 9 11 / 16 / 2011 (2nd ballot)
used non-linear FE programs available in the United States include ANSYS1, ABACUS2, ADINA 3 and NX 1
NASTRAN4. There are also many proprietary FE programs that have been designed specifically to consider the 2
cracking problem for reinforced concrete containment structures. 3
4
2.3.2 Linear SimplifiedFE Analysis 5
Linear Simplified FE analysis is usually used only in the preliminary design. Two possible approaches include: 6
a) Reduced-Stiffness / Cracked-Section Approach: The calculation is performed using a linear finite element 7
analysis where the reduction in stiffness due to cracking is considered. However, it should be noted that this 8
is a very time consuming process and is thus usually only used in the preliminary design. 9
b) Moment-Curvature Approach: The moment curvature response isproperties are obtained using a concrete 10
section analysis program by implementing in conjunction with: 11
• non-linear stress-strain material properties, and 12
• a non-linear shell formulation that accounts for the cracking induced stiffness redistribution. 13
• This moment-curvature approach would only be suitable for consideration of the steady state linear 14
thermal gradient case and should also be used only for preliminary design. 15
16
2.3.3 Mesh Type and Size 17
The linear or non-linear FE model will usually be axisymmetric or a small slice 3D model of the containment for 18
consideration of the general case of a symmetric LNG RLG spill loads and a larger sector separate model for 19
consideration of the LNG RLG spill case where non-axisymmetric discontinuities are considered. 20
21
Typically, the structural model contains a fine-mesh or a high density of solution points. The model includes the 22
base slab, foundation springs, containment wall, roof structure and local discontinuities, such as the prestressing 23
buttresses. If the liners are considered as structural members, theyLiners should be included tooif they are 24
considered as structural members. 25
26
A more detailed substructure model of the region above the TCP anchorage might be considered in order to 27
reduce the computational demand, provided it can be demonstrated that the boundary conditions and loadings 28
correctly represent the global model. 29
30
The reinforcing and prestressing steel should may also be modeled and the prestressing forces applied as part of 31
the loading or construction sequence. 32
33
2.3.4 Loading 34
Comment [LE58]: Part of 056 Jiang
Comment [LE59]: 051 Mash Comment is “We should exercise caution. A number of vendors have historically used this approach and we ought not to say it should not be used.” No change, non-persuasive. Tue 3-20 - (3/3) Pawski, Garrison, Ballard) 053 Jiang Deleted sentence in its entirety (11/11 Wu, Pawski, Hoff, Berner, Howe, Berner, Hjorteset, Garrison, Ballard, DJ, Brannan, NKO) 052 Hoptay Withdrawn Monday March 19. 054 Mash Not addressed, but deletion of the sentence should satisfy comment that “contractors should be able to choose design method.
Comment [LE60]: 055 Wu Withdrawn Monday March 19. 056 Jiang Revised as shown. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO) 057 & 058 Mash not addressed. Leave as is.
Comment [LE61]: 077 Khalifa: Pg 9 line 19 add "separate" before "model." 21-Oct-2013 Phoenix
Comment [LE62]: 059 Jiang Revise as shown. (12/12 Wu, Pawski, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE63]: 060 Jiang No change. (13/13 Wu, Pawski, Hoff, Berner, Howe, Hanskat, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO)
Comment [LE64]: Pg 9 line 24 Hoff: editorial Change last sentence to read 21-Oct-2013 Phoenix
Comment [LE65]: 061 Jiang - withdrawn
Comment [LE66]: 062 Wu Comment is “Change the word, “may” to “should”, since the reinforcing and pre-stressing steel need to be included in the nonlinear FEM cracking analysis in the liquid spill case.”
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 10 11 / 16 / 2011 (2nd ballot)
The LNG RLG spill case should include hydrostatic pressure from the LNG RLG fluid in the annular space. 1
Dead load, live load and steady state temperatures coincident prior to the LNG RLG spill, shall be applied prior 2
application of the temperature transients. 3
4
5
Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite 6
difference solution. The thermal model used for determining nodal temperatures This thermal model is also a 7
high density model which should include concrete foundation, soil thermal boundary condition, walls, roof and 8
outside or inside ambient temperature boundary conditions. This model should also include the base slab 9
insulation and the thermal corner protection insulation. 10
11
2.3.5 Heat Thermal Analysis 12
The heat transfer analyses should consider both maximum (95th percentile) and minimum (5th percentile) ambient 13
temperatures. The LNG RLG spill is applied internally to the containment and the adjacent tank fire case is 14
applied externally. The LNG RLG spill load case should also include the vapor temperature generated from the 15
spill above the liquid level. Nodal temperature time histories are computed and mapped to the structural finite 16
element model. The concrete wall internal temperatures from the thermal model are also typically used to 17
determine the for selection and placement of normal (A615), cold-temperature (A706) and cryogenic 18
reinforcingreinforcement complying with the requirements of ACI 376. 19
20
The LNG RLG hydrostatic pressure and temperature time histories are applied gradually and the iterative solution 21
computes concrete stresses and strains, crack locations and reinforcing stresses. 22
23
24
2.4—Material Constitutive Models 25
26
2.4.1 Concrete Constitutive Model 27
Recognized concrete constitutive models shall should be used in the analysis. Examples include material models 28
described by Eurocode 25 and shown in the Figure 2.1 below. The concrete constitutive model should also 29
account for reduction in tensile stiffness after cracking of concrete including the effects of tension stiffeninglinear 30
tension stiffness effects with tension failure or reduction in stiffness at the cracking strain of the concrete. 31
32
Figure 2.1: Stress-Strain Diagram for Uniaxial Compression from Eurocode EN 2 1992-1-1 33
Comment [NKO67]: 063 Mash Comment is “Seems out of place in terms of the flow of the document.” 063 Oliver negative - not addressed
Comment [LE68]: 064 Pawski Change as shown. (9/9 – see Saturday attendance)
Comment [LE69]: 065 Mash Comment is “Vapour temperature? This will be affected by convection etc? How is this to be determined.” This is a general comment/question. No new text proposed. Leave as is and consider the issue in the future.
Comment [LE70]: 066 Hoptay Revise as shown. FUTURE ACTION: revisit use of A706 materials in ACI 376 section 4.7.2. Mon 3-19 -(9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE71]: Pg 10 line 28 Hoff: editorial Use "should" in non-mandatory TN 21-Oct-2013 Phoenix
Comment [LE72]: 079 Khalifa: Revise pg 10 line 30 to read: 21-Oct-2013 Phoenix
Comment [LE73]: Typo (see page 8)
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 11 11 / 16 / 2011 (2nd ballot)
1
The σc – εc material relationship shown in Figure 2.1 is taken from Eurocode EN 2 Part 1, 4.2.1.3.1 (4.1). 2
3
For short term loading the relationship is defined as: 4
σc/fc = (k.n-n2)/[1 + n.(k-2)] (1)
where: 5
fc concrete compressive strength at 28 days (N/mm2) < 0.0 (2)
εcu ultimate strain < 0.0 (3)
n = εc/εc1 (both < 0.0) (4)
εc1 = -0.0022 (strain at the peak stress fc) (5)
k = (1.1Ec,nom).εc1/fc (6)
Ec,nom = Ecm/γc (kN/mm2) (7)
γc partial safety factor = 1.5 unless justified by adequate control procedures. (8)
Ecm = 9.5(fc + 8)1/3 (Ecm in kN/mm2; fc in N/mm2) (9)
6
The tension side of the �c – �cfc - εc material relationship may be taken as: 7
σc = Ecmεc (N/mm2) for σc < fctm (10)
σc = 0 for σc > or = fctm (11)
where: 8
fctm = 0.30fc2/3 (N/mm2) (13)
9
In reality, the tensionTension softening is usually introduced following rupture of the concrete in order to provide 10
for numerical stability in the solution. 11
12
2.4.2 Steel Constitutive Models 13
Comment [LE74]: 067 Wu Comment is “Need to specify the value for ɛcu = 0.3%” Insert in Figure 7 if editing is possible.
Comment [LE75]: Typo
Comment [LE76]: 068 Pawski - withdrawn Add a tension “tail” to the figure. (Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
Comment [LE77]: Pg 11 line 7 Hoff & Widianto: editorial Stress symbols are missing 21-Oct-2013 Phoenix
Comment [LE78]: 069 Pawski - withdrawn Editorial, change as noted. (Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, Brannan, NKO)
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 12 11 / 16 / 2011 (2nd ballot)
Figure 2.2 shows a typical uniaxial stress strain curve for reinforcing steel and Figure 2.3 a typical uniaxial stress-1
strain curve for prestressing steel. 2
3
Figure 2.2: Typical Uniaxial Stress-Strain Curve for
Reinforcing Steel from Eurocode EN 2 1992-1-1
Figure 2.3: Typical Uniaxial Stress-Strain Curve for
Prestressing Steel from Eurocode EN 2 1992-1-1
4
5
Other concrete and steel constitutive models may be used provided it can be demonstrated that these models 6
accurately characterize material behavior. 7
8
2.4.3 Selection of Material Parameter Values 9
Since forFor the LNG RLG spill case, it is critical that cryogenic liquid be prevented from migrating behind the 10
TCP, and conservative assumptions should be used when selecting material properties. 11
12
2.4.3.1 - Compressive Response 13
It should be noted that the extent of the compression zone is not as critical as the size and extent of the cracks. 14
Therefore, the use of the mean compressive concrete strength is adequate for crack width calculations. The mean 15
modulus of elasticity of the reinforcing and prestressing steel and concrete is also considered adequate. 16
17
2.4.3.2 - Tensile Properties 18
For tension properties, the minimum yield strength of the reinforcing should be considered to maximize the crack 19
width. Also, if tensile strength of the concrete is considered, the analysis should evaluate the 95th and 5th 20
percentile concrete tensile strength limits. A more conservative approach would be to consider no tensile capacity 21
of the concrete in the analysis. 22
Comment [LE79]: 070 Wu Comment is “Need to specify the limiting ultimate steel strain, ɛu.
(Note that the ultimate strains for steel are not discussed in the Code. Committee should discuss, and set the allowable limits. ) CONSIDER FOR FUTURE ACTION
Comment [LE80]: Typo
Comment [LE81]: Pg 12 lines 10 & 11 Hoff: editorial. Change to read 21-Oct-2013 Phoenix
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 13 11 / 16 / 2011 (2nd ballot)
1
2.4.3.3 - Temperature Effects on Material Properties 2
Improved material properties at low temperature, should not be used unless adequate cryogenic testing has been 3
carried out to confirm these material properties. The variation of the mean coefficient of thermal expansion with 4
temperature should also be considered in the solution. 5
6
2.5—Crack Width Calculations 7
The Code suggests that Eurocode EN 2 Part 1 4.4.2.4, (4.80) be the basis for calculation of crack widths. In this 8
approach crack width is determined from steel strains using the following relationship: 9
wk = βsrmεsm (14)
where wk is the 95th percentile crack width, εsm is the mean steel strain, srm is the average final crack spacing and β 10
is a design value that can be taken as: 11
• 1.7 for load induced cracking and for restraint cracking in section with minimum dimension in excess of 800 12
mm, or 13
• 1.3 for restraint cracking in sections with a minimum dimension depth, breadth or thickness, (whichever is the 14
lesser) of 300 mm or less. 15
16
The average final crack spacing, srm, is computed from Eurocode 2 Part 1, 4.4.2.4 (4.82) as: 17
srm = 50 + 0.25k1kk2φ/ρr (15)
where: 18
φ is the barsize or average bar size in mm (16)
k1 = 0.8 for high bond bars and 1.6 for plain bars (17)
k = 0.8 for tensile stresses that are due to intrinsic deformations (18)
k2 is a coefficient which accounts for the form of the strain distribution and is between
0.5 for bending and 1.0 for pure tension.
(19)
ρr is the effective reinforcing ratio, As/Ac,eff, where As is the area of reinforcement
contained within the effective tension area, Ac,eff
(20)
19
The mean strain value, εsm, should be computed directly using the non-linear finite element model and considering 20
all loads existing at the time of cracking. More specifically, the mean strain is obtained by averaging calculated 21
strain over the length of steel that has exceeded the yield limit. In other words, for a single piece of reinforcing 22
steel that has exceeded yield, εsm would be computed as the integrated strain over the length of the plastic zone of 23
the reinforcing divided by the length of the plastic zone. 24
25
Comment [LE82]: 072 Mash Comment is “Need to look into this area in more detail and will advise through discussion.” This is a general comment.. No new text proposed and no additional input provided sine the last ballot. Leave as is and consider the issue in the future.
Comment [LE83]: 071 Wu Monday march 19 withdrawn because 2004 edition equations will be used. 074 Garrison negative and 2012.10.13 Phoenix Wu negative – not addressed . To update equations to 2004 edition.
Comment [LE84]: Typo
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 14 11 / 16 / 2011 (2nd ballot)
REFERNCES 1
1. ANSYS Inc., Canonsburg, PA 2
2. ABACUS, Inc., Providence, RI 3
3. ADINA R & D, Inc., Watertown, MA 4
4. Siemens PLM Software, Plano TX 5
5. EUROCODE 2 Design of concrete structures – Part 1 General rules and rules for buildings 6
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 15 11 / 16 / 2011 (2nd ballot)
Appendix A: ACI 376 Code TCP Requirements 1
2
CHAPTER 2—NOTATION AND TERMINOLOGY
thermal corner protection (TCP)—insulated and liquid tight system to protect the outer
tank from thermal shock.
calculated crack width—crack width calculated using a concrete constitutive model
defined in 8.1.1.7.
CHAPTER 6—MINIMUM PERFORMANCE REQUIREMENTS
6.3.2—Under spill conditions, the concrete above the thermal corner protection (TCP)
should remain liquid tight, based upon minimum depths of compression and
precompression.
6.3.4—Calculated crack widths should be considered at TCP embedment when cracking
would result in liquid product migrating behind the TCP and compromising its
effectiveness.
The embedment zone should extend a minimum of two times the wall thickness above the
TCP anchorage. Calculated crack widths should not exceed 0.0040.008 in. within the TCP
embedment
zone.
CHAPTER 8—ANALYSIS & DESIGN
8.1.1.7—Cracking and tension stiffening
should be included by appropriate
modification of the material stress strain
relationship or by the use of finite elements
that have the capability of cracking under
R8.1.1.7—The Eurocode 2 is recommended
for determining calculated crack widths. In
this case, the calculated crack widths are
characteristic and not mean calculated crack
widths.
Comment [LE85]: 075 Pawski Resolution is: This is an editorial comment. Appendix A is a “copy” of what is in the Code. It is provided for reader’s convenience. Reconcile duplication between 2.1 and Appendix A, such as removing Appendix A
Comment [LE86]: 074 Garrison Response is: 1)Definition of the spill loading is beyond the scope of the current TN and will thus be addressed in a separate document defining LNG spill conditions. 2)Update and change the model to the latest 2004 edition of the Eurocode,
(Sunday: present - Wu, Pawski, Hoff, Berner, Howe, Brnnan, Hjorteset, Hoptay, Garrison, Ballard, NKO)
Comment [LE87]: 073 Wu Comment is “Change the crack width of 0.004 in to 0.008 in.” Section 6.3.4 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 16 11 / 16 / 2011 (2nd ballot)
tension, and crushing under compression as
well as the ability to include reinforcing
steel.
Unless otherwise specified, the concrete
constitutive mode from European Code
should be used for determining calculated
crack widths.
Extensive field experience with liquid
retaining and offshore concrete structures
has demonstrated that satisfactory liquid
tightness and liquid retaining performance
can be achieved by imposing calculated
crack width limits.
However, it must be noted that calculated
crack width represents an average numerical
value that is not directly equivalent to
calculated crack width measured in the field.
Due to the non-homogeneous nature of
concrete, calculated crack width values
measured in the field will vary from
calculated values, and therefore they cannot
be directly compared to calculated crack
widths.
1
Comment [LE88]: 076 Thompson Comment is “Remove the last sentence from the Code Commentary: “Due to the non-homogeneous nature of concrete, calculated crack width values measured in the field will vary from calculated values, and therefore they cannot be directly compared to calculated crack widths.”” Section R8.1.1.7 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
ACI 376 (markup update 2014.01.08) TCP Design & Analysis
March 21, 2013 Phoenix – cumulative markups 17 11 / 16 / 2011 (2nd ballot)
1
2
Page 6: [1] Comment [LE35] rpawski 1/14/2014 3:42:00 PM
025 Wu Revise 1.2.3 as shown and as new section 1.2.4 as shown. (9/9) Wu, Pawski, Howe, Hoff, Hoptay, Garrison, Ballard, Brannan, NKO) 2013.10.21 Phoenix – consensus was new section 1.2.4 is not needed and should be deleted in its entirtety.
Page 8: [2] Comment [LE53] rpawski 1/14/2014 3:42:00 PM
042 Pawski – Sat (superceded) 043 Jiang – delete as shown. Sunday 3-18 - (11/11 Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, NKO)
Page 8: [3] Comment [LE54] rpawski 1/14/2014 3:42:00 PM
044 & 047 Garrison negative – not resolved 044 Mash & 047 Jiang - Revise as shown. Tue 3-20 - (3/3) Garrison, Ballard, Pawski & Sun 3-19 - (12/12 Wu, Pawski, Hoff, Berner, Howe, Hjorteset, Hoptay, Garrison, Ballard, DJ, Brannan, NKO) 045 Hoptay – withdrawn
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 1 of 15
Technical Note on TCP (TCP – TN) Approved Sections Section Approved with Comments to be resolved Negative Vote 2013.04.13 376-C Minneapolis
Members that Voted Voting Members that did not vote 2013.04.13 – 376 D Minneapolis
Voting Members that voted (79%) 1. Hjorteset, Kare 2. Brannan, Mike S 3. Allen, Junius 4. Ballard, Thomas A 5. Garrison,Jeffrey 6. Hatfield,Alan 7. Hoff, George C 8. Hoffmann, Richard A
9. Hoptay,Joseph 10. Howe, Thomas R 11. Jiang,Dajiu 12. Khalifa, Jameel U 13. Krstulovic-Opara, Neven 14. Legatos, Nicholas A 15. Malhotra,Praveen 16. Mash,Keith 17. Moncarz, Piotr D
18. Nussmeier, Robert W 19. Oliver, William H 20. Pawski, Rolf P 21. Rushing, William E 22. Wu,Sheng-Chi
Associate Members
� Roetzer, Josef � Widianto, Widianto
23. Hanskat, Charles S 24. Douglas,Hamish 25. Hashmi, Humayun 26. Rajan, Ramanujam S 27. Sward,Robert 28. Thompson,Eric
Members Attending: 1. Brannan, Mike 2. Hjorteset, Kare 3. Ballard, Thomas 4. Garrison. Jeffrey 5. Hoff, George 6. Hoptay, Joseph 7. Howe, Thomas 8. Khalifa, Jameel
9. Pawski, Rolf 10. Hanskat, Charles 11. Roetzer, Josef
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
1
Brannan
I am not sure the TCP can be constructed as detailed because it would be impossible to weld both sides of the TCP plate to the embedment plate. It would also be better to radius the sharp corner shown on the TCP plate. Would it be possible to simply lap weld the TCP plate to the embedment plate? Should the embedment zone also extend 2X the wall thickness below the embedment plate?
The comment found partially persuasive. It is not intended that the TN covers TCP construction details. Furthermore, welding requirements should be as per API 620. Address the comment by revising text on page 1 lines 11-14: INTRODUCTION ACI 376 provides requirements and some basic recommendations for the design of the Thermal Corner Protection (TCP) embedment zone. The purpose of this Technical Note document is to provide further guidance for on (a) design and analysis of the TCP embedment anchorage detailing and (b) TCP liquid-tightness analysis (i.e., crack width calculations) in the TCP embedment zone (i.e., crack width calculations). Update title to read: Thermal Corner Protection Design & Crack Analysis
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Humayum, Howe, Wu, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negatives requiring discussion: ~ Ref. no. 1, Comment 6 - Ballard proposed addition to Introduction ~Ref. no. 1, Comments 8, 9, 10 - edit Fig. 1.1
Agree with comment - Hoffman
With Respect to M. Brannan’s Comments, it is my opinion this can be welded from both sides, by making this attachment weld first and then going on with the construction. There will be a “fill-in plate that is required to build up the TCP side wall. I have no objection to the proposed changes
UPDATE NOTES (2013.01.08) a) 2013.10.21 Phoenix discussion items are on pg 14 of 15. b) See the following Ref. no. for NEGATIVES REQUIRING FURTHER DISCUSSION:
1, 18, 32, 37, 41, 44 & 47, 49, 63, 74. c) Pg. 15 of 15 has Legatos negative that requires further discussion.
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 2 of 15
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
Design and Analysis of the TCP Embedment Zone
Disagree - Ballard I believe the embedment zone should extend at least to the bottom of the TCP plate since migration of cracks in this zone would compromise the leak tightness of the detail. NOTED in Fig 1.1(b).
2013.04.13 – 376-C Minneapolis: Agreed and that Tom Ballard to propose wording. From TB email dated 2013.04.15: “Although the code and this TN do not explicitly define leak tightness criteria for the anchorage and embeddment, the design and construction of these components should be carried out with the clear objective of protecting the corner joint from product temperatures.” Note – added to Introduction on pg 2.
8 Page 5, line 2, item 3
Mash
Suggest rewording and removing 'substantially' link to definitive acceptance criterion to avoid confusion. Suggest exact acceptance criterion words such as - under the spillage condition the crack widths on the inside face shall be limited to xx, compressive stresses in both the meridional and vertical directions shall be minimum y, max z,
The comment found partially persuasive. Limiting values are covered in the Code (e.g., compressive zone size, crack width limits, etc.) and do not need to be repeated here. Revise text for clarity to read: “The concrete wall above the TCP, directly exposed to spilled product, should remain liquid and substantially vapor tight during the spill condition. This is assured by maintaining a compression zone in the wall exposed to the spill and by and limiting the crack width cracking on the inside face of the wall in the vicinity of the TCP embedment plate zone during a spill.”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with editorial changes – Khalifa, Roetzer, Krstulovic
“The concrete wall above the TCP, directly exposed to spilled product, should remain liquid tight and substantially vapor tight during the spill condition. 2013.04.13 – 376-C Minneapolis: Agree with comment.
10 Page 5 Line 10
Hoptay
The material selection is temperature dependent and to state that the TCP is 9% Ni infers an LNG tank and not RLG tanks in general.
The comment found persuasive. Change text to read: “Material selection and material requirements used in the design of the 9% nickel-steel TCP and secondary bottom plates may be performed in accordance with API 620.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Note – This sentence is deleted based on Comment LE15 in text markup.
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
Disagree - Douglas This may still be ambiguous as API 620 does not refer to TCP
2013.04.13 – 376-C Minneapolis: Change last line to read: “… should be in accordance with API 620.”
11 Page 5, line 4, item 6
Mash
Assurance is through cracks + compression zones not through cracks alone. Crack width limitation in the vicinity of the embed is to prevent liquid migration behind the TCP area.
No action. Covered in previous response.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
13 P. 5, Line 15
Wu
add “seismic Aftershock load”. The comment found persuasive. Change text to read:
“The TCP embedment plate should be designed to resist radial and vertical loads and moments resulting from both (a) thermal gradients, as well as (b) mechanical forces that develop during a spill condition including SSEAFT. The TCP design consists of the following steps:”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
15 Page 5, line 21, item 10
Mash
Starting temperatures and conditions should be selected so as to maximise the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby creating maximum straining across the section.
The comment found persuasive. Add proposed text to line 22: 1.2.1 – STEP 1: TCP Load Definition Finite element analyses is performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, hydrostatic pressure and hydrodynamic pressure due to seismic aftershock. Starting temperatures and conditions should be selected so as to maximize the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby creating maximum straining across the section.
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Legatos, Widianto, Hoptay, Roetzer, Hatfield, Krstulovic
2013.04.13 – 376-C Minneapolis: To address all comments, replace last three sentences with: “ Initial temperatures and conditions should be selected to obtain the most severe design conditions. For instance the most severe condition for design of the anchors is likely to be a warm wall (summer) with a cold thermal shock to the embedment.”
Agree with editorial changes - Hoff
For instance, for the design of the anchors, the critical condition is likely to be a warm wall (summer) and with a cold shocking to the embedment, thereby creating maximum straining across the section.
Agree with minor comment - Humayum
last sentence - straining or strain?
Agree with minor comment - Brannan
consider using “Design” instead of “Starting”.
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
Page 4 of 15
1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
Agree with editorial changes - Pawski
Starting temperatures and conditions should be selected so as to maximize the demand under consideration. For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking thermal shock to the embed. Whereby creating maximum straining across the section.
Agree with editorial changes - Douglas
Pawski 2013.04.23 – Allen comment below shown incorrectly as Douglas and deleted here. Correct comment is: "…....... cold shock to the embed which results in the maximum strain across the section " Douglas additional comment1 at end of Ballot Summary: "1. Page 5, Para 1.2.1 Line 24: Also Comment LE27: What is the advantage of the use of the term "demand" as opposed to load? If a new term is to be introduced then it's use must be defined: When is a load a demand?" Pawski 2013.04.23 – this is addressed by 376-C Minneapolis response above.
Agree with editorial changes - Allen
For instance for the design of the anchors the critical condition is likely to be warm wall (summer) and cold shocking to the embed. Whereby Thereby creating maximum straining across the section.
Agree with changes - Oliver
Agree with suggested grammatical revision: Starting temperatures and conditions should be selected so as to maximize the resulting stresses in the component under consideration. For example for the design of the anchors, the critical condition is likely to be warm wall (summer) and cold shocking to the embed, creating maximum straining across the section. Comment: What does demand mean in this context? If not revised, add “demand” to definitions.
16 P. 5, Line 22, at the end of the paragraph
Wu
Add “and hydrodynamic pressure due to seismic aftershock”.
The comment found persuasive. Change text to read:
• “Finite element analyses is performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall. Loads should include all loads that the TCP and the embedment will be subjected to including thermal, prestress, creep, concrete shrinkage, internal pressure, hydrostatic pressure and hydrodynamic pressure due to seismic aftershock (SSEAFT).”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Allen, Legatos, Widianto, Hoptay, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with editorial change – Khalifa, Douglas, Roetzer, Krstulovic
“Finite element analyses is are performed first to determine forces resulting from thermal gradients applied to the TCP, TCP embedment plate and outer concrete wall.
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
18 Page 5, line 28, item 12
Mash
Suggest inclusion of the words 'in the absence of a defined leak rate all intermediate levels shall be investigated. In practice this may be achieved by running a number spill levels to so as adequately bound the demands. Typically 5 levels may be used dividing the spill height into 4 equal units. In addition levels in close proximity to the TCP must be investigated.
Agree in principle with comment. Revise as noted and address spill levels in a future edition of the Code.
• “Various spill levels should be considered to determine the most severe effect on the embedment and concrete wall. This should include a spill levels located just below the top of the TCP which will place the largest temperature differential between the TCP and the concrete wall. as well as various Also a minimum of three levels should be considered for spill levels above the TCP up to, at top of the TCP embedment zone, at mid-height, and full spill height. “
Agree – Jiang, Moncarz, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Allen, Legatos, Widianto, Roetzer, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negative requiring discussion: ~ Ref. no. 18, Comment 25 – number of locations 5 or 3 2013.04.13 – 376-C Minneapolis: Mash comment non-persuasive. Three is a minimum and does not preclude specifier from requiring or the designer choosing more.
Agree with suggested change -Khalifa
This should include a spill levels located just below the top of the TCP which will place generate the largest temperature differential between the TCP and the concrete wall.
Agree with editorial changes – Hoff, Pawski
This should include a spill levels located just below the top of the TCP which that will place the largest temperature differential between the TCP and the concrete wall Also A minimum of three levels should be considered for spill levels above the TCP up to,1) at top of the TCP embedment zone, 2) at mid-height, and 3) at full spill height.
Agree with editorial changes - Douglas
This should include a spill levels located just below the top of the TCP which will place result in the largest temperature differential between the TCP and the concrete wall
Agree with editorial changes - Hoptay
“…at the top of the TCP embedment zone, at mid-height, and full spill height”
Agree with editorial comment - Oliver
Change “place” to “produce”. Observation: The proposed text requires four levels, not so far from five.
Disagree - Mash Statement of 3 levels does not reflect the significance of the analysis. This is the most important analysis carried out for the outer tank and it is essential that an appropriate amount of levels be considered. Suggest that the text is amended to the following: Also a minimum of three five levels should be considered
20 Page 5, line32, item 14
Mash
Must be achieved through mechanical anchoring! The comment found persuasive. Revise to read: “The TCP embedment plate should be cast in place and mechanically anchored to the concrete wall or by other suitable means (e.g., ???). Anchor bolts (studs) should be placed in continuous (circumferential) rows along the concrete wall.”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Oliver, Pawski, Hatfield, Brannan,
ACI 376 - Technical Note on TCP 2nd ACI 376-C Ballot on TCP Technical Note Last Update: 4 / 13 / 2013 - 376-D meeting in Minne apolis Balloted from 1 /2 0 to 3 / 10 / 2013 2012
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1st Ballot Results (Approved w. Comment) 2nd Ballot Results
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS
Suggested Change
Krstulovic
Agree with suggested change -Khalifa, Roetzer
Delete second sentence completely as the same is essentially said in the next sentence. “The TCP embedmPartent plate should be cast in place and mechanically anchored to the concrete wall. Anchor studs should be placed in continuous (circumferential) rows along the concrete wall.” 2013.04.13 – 376-C Minneapolis: After discussion it was agreed delete second sentence as suggested.
Agree with suggested change -Garrison
Modify last sentence: “ Anchor studs should be welded in continuous circumferential rows along the embed plate.”
2013.04.13 – 376-C Minneapolis: Withdrawn after discussion on deleting second sentence as per Khalifa, Roetzer, and Hoptay.
Disagree -Hoptay 2014.01.08 TCP text - negative is resolved
Delete second sentence because next sentence covers the same information
2013.04.13 – 376-C Minneapolis: After discussion it was agreed delete second sentence as suggested.
21 Page 6, line 1, item 1
Mash
When? Embedment must be anchored with studs? The comment found persuasive. Revise to read as noted below. Address questions on spacing and gap size in future: • “When the The embedment plate isshould be anchored with
circumferential studs, a minimum of two rows of circumferential studs should be used to anchor the embedment plate. The spacing between mechanical anchors (studs) has significant impact on the TCP emebedment performance and thus should be considered in the design. should be limited to ensure that the axial, bending and shear stresses in the embedment plate are within the allowable stresses.”
2014.01.08 TCP text negative requiring discussion: ~ Comment 27 – number of locations 5 or 3
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Hatfield, Krstulovic
Agree with comments -Pawski
Bullet points 1 & 2 should be combined Use “studs” or “bolt studs” consistently
Agree - Brannan Note that our Figure 1.1a shows four rows of circumferential studs. Should it show two rows of studs in solid line ink and the other two in shaded or dashed ink to indicate the potential for using more than two rows?
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2013.04.13 – 376-C Minneapolis: Agree, annotate sketch to state “2-rows minimum.”.
Agree with editorial changes - Khalifa
Also recommend deleting bolts from first line under section 1.2.3
2013.04.13 – 376-C Minneapolis: “Anchors” to be used throughout. Edit TN and replace bolts & studs with “anchors.”
Disagree – Hoptay 2014.01.08 TCP text - negative is resolved
Disagree – studs are not always used for consistency suggest the following rewording The embedment plate should be anchored with a minimum of two circumferential rows of anchors. The spacing between anchors has significant impact on the TCP embedment performance and thus should be considered in the design. 2013.04.13 – 376-C Minneapolis: Persuasive, use proposed wording.
26 Page 6, line 19, item 4
Mash
Nothing mentioned regarding detailing? Suggest inclusion of words such as. Ideally crack control is best achieved through the introduction of smaller bars at closer spacings as opposed to larger bars at wider spacings. In this regard it is suggested that the bar spacing be selected so as to enable the subsequent introduction of lacer bars to the system. Therefore adoption of bar spacings of between 150 and 200mm is recommended in the vicinity of the TCP whereby allowing additional bars top be slotted in. Anchor spacings should be selected to as to be multiples of the bar spacing to enable a clash free design.
The comment found non-persuasive regarding suggested inclusion of bar detailing because this is normal everyday concrete detailing. Add the following after line 7 on page 6.
• “Anchor spacings should be selected to as to be multiples of the bar spacing to enable a clash free design. “
Delete lines 6 and 7 on page 6.
• “ Allowable stresses i.e., material selection and material requirements used in the design of the embedment plates, may be selected in accordance with API 620.”
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Hoff, Hoptay, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
NEW Page 6 Para 1.2.4
This comment inserted by Pawski 2013.04.23 Douglas additional comment 2 at end of Ballot Summary: The liquid tightness criteria are specified in Para 2.1, items 1 & 2. Additional tightness criteria on “embedment plates” should not require to be defined by owner. I am not in favour of definitions to be provided by owners. The statement is vague and ultimately provides no guidance.The code is to provide guidance to all, including owners.
Douglas Note – consensus at 2013.10.21 Phoenix meeting was to delete the new section 1.2.4
28 Page 7, line 1 4, item 1
Mash
Suggest using nomenclature such as demand as opposed to load.
The comment found persuasive in part. Revise to read. “When subjected to During the spill condition, the concrete wall will be loaded with subjected to high forces due to mechanical loads and thermal effects and mechanical forces. These forces that will lead to significant wall cracking. During the spill condition, integrity Integrity of the concrete wall must be maintained. As specified in the ACI 376 Code, the wall should
Agree – Jiang, Moncarz, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Roetzer, Oliver,
Note – Mash negative resolved . Wording incorporated into 2014.01.08 TCP markup is essentially as suggested by Mash, as follows: During the spill condition, the secondary concrete wall will be subjected to high large forces due to mechanical loads and thermal effects that will lead to significant wall cracking. Integrity of the concrete wall must be maintained. As specified in the ACI 376 Code, the wall should remain liquid
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remain liquid and substantially vapor tight. More specifically:”
Pawski, Hatfield, Brannan, Krstulovic
and substantially vapor tight.
Agree with editorial changes - Hoff, Krstulovic
During the spill condition, the concrete wall will be subjected to high forces due to mechanical loads and thermal effects that will can lead to significant wall cracking.
2013.04.13 – 376-C Minneapolis: Discussed and agree with comment.
Disagree – Hoptay 2014.01.08 TCP text - negative is resolved
Suggest rewording sentence as follows to cover both the transient and steady state condition. The integrity of the concrete wall must be maintained during the entire spill. 2013.04.13 – 376-C Minneapolis: Withdrawn.
32 Page 7, line 20, item 6
Mash
EN only calculates characteristic widths. Historically US codes have cocooned the crack width requirements into the detailing rules, These were based on the Gergely Lutz expressions which used mean widths. Replace 'as per' with 'in accordance with'
The comment found persuasive. Revise page 7 lines 20-21 to read. “3) ACI 376 section 8.1.1.8 - requires that the cracks widths should be calculated as characteristic and not mean calculated crack widths. as per EN 1992-1-1.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Ballard, Malhotra, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negatives requiring discussion: ~ Ref. no. 32, Comment 48 – Mash, Wu & Garrison negatives . 2013.04.13 – 376-C Minneapolis: Agree with Wu. NEW BUSINESS for CODE - JG write the new business item on code change form Q1.
Disagree - Wu Suggest that: a) EN 1992-1-1 should stay, as stated in ACI 376 to delete “as characteristic and not mean”
2013.04.13 – 376-C Minneapolis: Persuasive since crack widths calculated by EN 1992-1-1 will be characteristic. Proposed wording to be adopted.
Disagree - Garrison b) Committee needs to review the ability of the contractor / designer to meet the requirement of 0.008” max crack width using EN equations for the spill condition (2 cryogenic temperatures). Experience shows that this is a difficult requirement to meet. Instead, perhaps ACI 376 should specify minimum rebar size and spacing within the TCP embedment zone.
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2013.04.13 – 376-C Minneapolis: Withdrawn pending future action by main committee. Jeff Garrison to prepare New Business (code change form Q1) proposal to address crack width values and method of calculation.
Disagree - Mash By removing the design code there is potential for use of codes that do not generate characteristic levels. In particular Model Code 90 is not prohibited, also Ven der Veen’s approach generates mean expectation of crack widths. There are some Contractors still purporting to MC90 and reviewer has a concern this will continue if left unchecked. Without guidance the Client is without a Captain and I uninformed. Note the NL Analysis is in accordance with EN so there should be no objection to using EN for crack widths. 2013.04.13 – 376-C Minneapolis: Considered as part of action item in the Garrison response.
34 Section 2.2.1 Page 7, Line # 31
1) Modeling
Jiang
Suggest to change to: 1) Modeling including modeling geometry and
material thermal properties
The comment found persuasive. Revise page 7 lines 20-21 to read.
1) “Modeling including specific tank geometry and material thermal properties”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
37 Section 2.2.1 Page 8, Line # 2 4) Continue analysis until steady state final temperatures are reached
Jiang
Suggest to change to: 4) Continue analysis until steady state final temperatures are reached and the temperature distribution is obtained
The comment found persuasive. Revise page 7 lines 20-21 to read. 4) “Continue analysis until steady state final temperatures are reached temperature distribution is obtained”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negative requiring discussion: ~ Ref. no. 37, Comment 48 – Garrison negative
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Disagree - Garrison Committee needs to define analysis / design requirements. Considering the variability in the possible loading conditions, variability in material properties and variability in modeling techniques it seems that a steady state analysis would be sufficient. 2013.04.13 – 376-C Minneapolis: Withdrawn.
41 Section 2.2.2 Page 8, Line # 8 “Apply dead load, prestressing and any other steady state load, iterate to equilibrium”
Jiang
Suggest to change to: “Apply dead, prestressing and any other steady state load”
The comment found persuasive. Revise page 7 lines 20-21 to read. “To establish initial conditions, aApply dead load, prestressing, normal-operating thermal and any other steady state load, then iterate to equilibrium”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negative requiring discussion: ~ Ref no. 41, Comment 52 – Garrison negative
Disagree - Garrison Committee needs to define analysis / design requirements.
44 Page 8, line 10, item 3
Mash
Determine strains in section, check for Residual Compressive Zone (RCZ), check for max comp stress etc.
The comment found persuasive. Change text to read: 5) “Beginning with the initial condition defined in step 2, cCompute crack widths at time steps times throughout the transient where reinforcing strains are the greatest. and exceed the material yield stress Furthermore, at each time step determine the adequacy of the compression zone.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
2014.01.08 TCP text negatives requiring discussion: ~ Ref no. 44 & 47, Comment 54 – Garrison negative
Disagree - Garrison Considering the variability in the possible loading conditions, variability in material properties and variability in modeling techniques it seems that a steady state analysis would be sufficient.
47 Section 2.2.2 Page 8, Line # 11 5) Computer crack widths at times throughout the transient where reinforcing strains are the greatest and exceed the material yield stress
Jiang
Suggest to change to: 6) Computer crack widths at times throughout the transient where reinforcing strains are the greatest and the stresses exceed the material yield stress
49 Page 8, line 18, item 7
Mash
What does this mean? The comment found persuasive. Change Page 8, lines 17-18 to read: “Calculation of cracking and crack widths for the RLG LNG spill condition and/or external fire condition shall be performed using a rational engineering analysis. Both linear Linear or non-linear finite element (FE) analysis should be used as
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Garrison, Douglas, Allen, Legatos,
2014.01.08 TCP text negative requiring discussion: ~ Ref no. 49, Comment 55 – Mash & Ballard negatives
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discussed in 2.3.1 and 2.3.2.”
Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic Disagree - Ballard CSA Z276 requires that fire and spill be considered
concurrently. I believe that this needs to be addressed in this paragraph.
Disagree - Mash Rational to one uninformed Engineer could be irrational to informed Engineer. Rational requires defining.
50 Section 2.3.1 Page 8, Lines # 21 to 23 “In this case a non-linear finite element program is used in conjunction with
• Non-linear FE material constitutive models for concrete and steel, and
• Crack width calculations as per E
Jiang
Suggest to change to: “In this case a non-linear finite element program is used by:
• Implementing the non-linear material constitutive relationship for concrete and steel
• Carrying out FE analysis to obtain stress counters, and
• Performing FE analysis post process to calculate crack width as per Eurocode 2 1992-1-1
The comment found persuasive. Change text to read: “In this case, a non-linear finite element program is used in conjunction with by:
• Non-linear FE material constitutive models Implementing the non-linear material constitutive relationship for concrete and steel and
• Carrying out FE analysis to obtain stress/strain contours, and
• Performing FE analysis post-process to calculate characteristic crack width, calculations following a method, such as as per Eurocode 2 EN 1992-1-1 (see section 2.5 in this TN).”
Agree – Jiang, Moncarz, Hoff, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with minor changes - Khalifa
Performing FE analysis post-processing to calculate characteristic crack width, following a method, such as Eurocode 2 EN 1992-1-1 (see section 2.5 in this TN).”
Agree with minor changes - Ballard
Change word “contours” to “distribution” or change sentence to “Carrying out FE analysis to obtain stresses and strains.”
Agree with changes - Widianto
To be consistent with Sections 2.3.1 and 2.3.2, suggest the sentence is re-worded as follows: "Non-linear or simplified finite element (FE) analysis should be used as discussed in 2.3.1 and 2.3.2" To be consistent with the last sentence in Section 2.3, I suggest that we switch the order between the current Sections 2.3.1 and 2.3.2 (i.e., present Simplified FE analysis in Section 2.3.1 and present non-linear FE analysis in Section 2.3.2. This will also be consistent with the progression of the actual design, where Simplified FE analysis is done in the preliminary design, before non-linear FE analysis.
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53 Section 2.3.2 Page 9, Lines # 2 & 3 “However, it should be noted that this is a very time consuming process and is thus usually used in the preliminary design.”
Jiang
Suggest to change to: “However, it should be noted that this is a very time consuming process and is thus usually used for focusing on more critical load cases after a preliminary screen for load cases has been performed in the preliminary design.”
The comment found persuasive. Remove the whole sentence. “However, it should be noted that this is a very time consuming process and is thus usually used for focusing on more critical load cases after a preliminary screen for load cases has been performed in the preliminary design.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Proposed wording incorporated into 2014.01.08 TCP text. .
56 Section 2.3.2 Page 9, Lines # 4 & 5 “Moment-Curvature Approach: The moment curvature response is obtained using a concrete section analysis program in conjunction with:”
Jiang
Suggest to change to: “Moment-Curvature Approach: The moment curvature response is obtained using a concrete section analysis program by implementing:” Comment: Weather should this approach be considered as “Linear Analysis” or “Non-linear Analysis”? May be this approach could be considered as a simplified non-linear analysis approach and should be used for preliminary only.
The comment found persuasive. Change text to read: “ 2.3.2 Simplified Linear FE Analysis Simplified Linear FE analysis is usually used only in the preliminary design. …… “ Moment-Curvature Approach: The moment curvature properties are response is obtained using a concrete section analysis program by implementing:”
• non-linear stress-strain material properties, and • a non-linear shell formulation that accounts for the cracking
induced stiffness redistribution. • This moment-curvature approach would only be suitable for
consideration of the steady state linear thermal gradient case and should also be used only for preliminary design.”
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Proposed wording incorporated into 2014.01.08 TCP text. .
63 Page 9, line 34, item 4
Mash
Seems out of place in terms of the flow of the document. The comment found persuasive. Edit text as shown below: “2.3.4 Loading The RLG spill case should …… Nodal temperature transients will typically be computed in a separate heat transfer finite element or finite difference solution. The thermal model used for determining nodal temperatures This thermal model is also a high density model which should include concrete foundation, soil thermal boundary condition, walls, roof and outside or inside ambient temperature boundary conditions. This model should also include the base slab insulation and the thermal corner protection insulation. “
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Pawski, Hatfield, Brannan, Krstulovic
Proposed wording incorporated into 2014.01.08 TCP text. . 2014.01.08 TCP text negative requiring discussion: ~ Ref no. 63, Comment 67 – Oliver negative not addressed
Disagree - Oliver This response does not address the basic comment that this whole paragraph doesn’t below under “Loading”. Suggest moving it to Section 2.3.3 “Mesh Type and Size”, or inserting a new section before “Loading” called “Thermal Model”.
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66 A Page 10 Line 10
Hoptay
On the code side of ACI 376 ASTM A706 is not referred to as low temperature reinforcing, only in the commentary. Can it be referred to as low temperature reinforcing in the technical note?
The comment found persuasive. Change text to read: “The concrete wall internal temperatures from the thermal model are also typically used for selection and to determine the placement of normal (A615), cold-temperature (A706) and cryogenic reinforcing complying with the requirements of ACI 376.” Furthermore, in a future Code revision, revisit the use of A706 materials in ACI 376 section 4.7.2.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Proposed wording incorporated into 2014.01.08 TCP text. . 2014.01.08 TCP text negatives requiring discussion: ~ Ref no. 74, Comment 83 – Garrison & Wu negatives
74
Garrison
1) Code and TN need to define conditions for transient thermal analysis for the spill condition (leak rate).
2) Why does TN reference withdrawn version of Eurocode
2 (DD ENV 1992-1-1:1992)? Current version is BS EN 1992-1-1:2004.
The comment found partially persuasive. 1) Definition of the spill loading is beyond the scope of the current TN
and will thus be addressed in a separate document defining LNG spill conditions.
2) Update and change the model to the latest 2004 edition of the Eurocode,
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Malhotra, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
Agree with comment - Ballard
Garrison was going to forward a copy of EN 1992-1-1:2004 to Ballard for updating the code equations in the TN.
???? - Garrison Agreed, loading and consideration of need for transient analyses needs to be reviewed.
75 Appendix A Pages 15-16
Pawski
It is redundant because it repeats paragraphs 2 through 4 in section 2.1 (page 7, lines 9-21)
The comment found non-persuasive. The comment found to be an editorial comment. Appendix A is a “copy” of what is in the Code. It is provided for reader’s convenience.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan, Krstulovic
76 Page 16, last paragraph in section R8.1.1.7
Thompson
Remove the last sentence from the Code Commentary: “Due to the non-homogeneous nature of concrete, calculated crack width values measured in the field will vary from calculated values, and therefore they cannot be directly compared to calculated crack widths.”
Section R8.1.1.7 is text copied over from the Code and provided herein for the user’s benefit. Text must remain as-is to properly reflect the Code requirement. Changes to be addressed only if/once the Code has been changed accordingly.
Agree – Jiang, Moncarz, Hoff, Khalifa, Rushing, Hoffman, Humayum, Howe, Wu, Ballard, Malhotra, Garrison, Mash, Douglas, Allen, Legatos, Widianto, Hoptay, Roetzer, Oliver, Pawski, Hatfield, Brannan,
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Krstulovic ADDITIONAL COMMENTS included with the ballots
Ref No. Text Author Comments
2ND BALLOT: RESPONSE being BALLOTED
Voting Member’s VOTE &
COMMENTS Page 4, line 8; Section 1.1
Oliver EDITORIAL: Add “the” “The primary function of TCP is to protect the already highly…”
Note - Added to TCP-TN markup (2014.01.08)
Page 6, Lines 28 - 30 Hoff Can we provide some guidance to the owner in this section? 10-21: Hoff comment resolution: The crack width requirements in section 6 are provided to for this purpose. DELETE 1.2.4 Note added to TCP-TN markup (2014.01.08) that new "1.2.4 Step 4" is to be deleted, and is shown for information.
Hjorteset Wu Billy Oliver Brannan Pawski Howe Garrison Hoff Hanskat
Wu
The liquid tightness criteria are specified in Section 2.1, Items 1 & 2. Why do we need additional tightness criteria on “embedment plates ” to be defined by owner?
Page 7, line 8 Pawski
Referenced section does not match final 376-10 1) ACI 376 section 6.3.3 6.3.2”
Note - Added to TCP-TN markup (2014.01.08)
Page 7, line 14 Pawski
Referenced section does not match final 376-10 2) ACI 376 section 6.3.4 6.3.3”
Note - Added to TCP-TN markup (2014.01.08)
77 Page 9, section 2.3.3, lines 19, Khalifa Add ‘separate’ before ‘model’ for clarity. Note - Added to TCP-TN markup (2014.01.08) 78 Page 8, section 2.3.1, line32, 33
Khalifa Revise to: Either a proprietary or one of several commercially available FE programs can be used for performing this calculation.
From hand notes: "Concur, combine first two sentences" Note - Added to TCP-TN markup (2014.01.08)
Page 9, line 24 Hoff
Change this sentence to read: “If Liners are considered as structural members, they should be included if they are considered as structural members too.”
10-21-13 Editorial Note - Added to TCP-TN markup (2014.01.08)
Page 10, line 28 Pawski
Use “should” in a non-mandatory TN “Recognized concrete constitutive models shall should be used in the analysis.”
10-21-13 Editorial Note - Added to TCP-TN markup (2014.01.08)
79 Page 10, section 2.4.1, line 30 Khalifa
Revise to: …account for reduction in tensile stiffness after cracking of concrete including the effects of tension stiffening.
10-21-13 Account for reduction in tensile stiffness after cracking of concrete . Note - Added to TCP-TN markup (2014.01.08)
Page 11, line 7 Hoff,
Widianto
The stress symbols are missing 10-21-13 Editorial Note - Added to TCP-TN markup (2014.01.08)
Page 12, lines 10, 11
Hoff
Change to read: “Since For the RLG spill case, it is critical that cryogenic liquid be prevented from migrating behind the TCP, and conservative assumptions should be used when selecting material properties.”
10-21-13 Editorial Note - Added to TCP-TN markup (2014.01.08)
Page 13, Section 2.5
Wu
The specified Code, EN2 part 1- 4.4.2.4 does not contain the equations for crack width calculation. The crack width calculation is shown in Section 7.3.4 of EN 1992-1-1 (2004 edition). Also, the equations shown here are not the same as the equations shown in EN 1992-1-1 (2004 edition). Please provide clarification.
10-21-13 Modify to address to match code and equations. Same as item 74
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To be addressed as future business:
Author Comments Legatos Conspicuous by its absence in the TCP-TN write-up is any reference to outer-wall designs that incorporate an impervious, continuous liquid-tight and vapor-tight liner.
This omission overlooks the crucial role such a liner plays in the formulation of criteria and parameters as they pertain to (a) the serviceability of the outer wall following a spill and/or thermal shock; (b) the specified limits on crack-width, residual wall compression, etc., etc.; and (c) the function, scope and design of the TCP itself. Moreover, this omission overlooks the differences between inner-versus-outer, and metallic-versus-non-metallic liners; and the role these differences similarly play in (a) through (c) above. If I am not mistaken, the only Code section that fleetingly mentions this subject with respect to the TCP is Section 6.3.3. This article provides guidance on what to do if a “leak-tight membrane/liner” is not used, but does not say anything about what to do in cases where such a liner is in fact used. The subject is also covered in 6.3.16.1 1nd 16.3.16.2, but those sections do not relate to the TCP. While I have not thoroughly perused the rest of the Code itself to see exactly where else this subject “belongs” and how it should be covered, I believe that TCP-TN coverage might fit in the following sections:
Section 1.1 (add a fifth paragraph) Fig. 1.1 (add Fig. 1.1 c) Section 1.2.4 Section 2.1