Date post: | 13-Apr-2015 |
Category: |
Documents |
Upload: | amitdutt1966 |
View: | 284 times |
Download: | 22 times |
R. A. Cook ACI Atlanta 2007 Hot Topic
1
1University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ANCHORAGE TO CONCRETEANCHORAGE TO CONCRETE-- SELECTION AND DESIGNSELECTION AND DESIGN
Ronald A. Cook, Ph.D., P.E.ProfessorDepartment of Civil EngineeringUniversity of Florida
2University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
APPLICATIONSAPPLICATIONS• Fasten an Attachment (Concrete, Steel,
or Timber Element) to Concrete, e.g.– Precast element to precast element– Roof truss to tilt-up concrete wall– Steel column to concrete footing– Wood frame to concrete– Connections to concrete in general
3University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
General Types of AnchorsGeneral Types of Anchors
Undercut ExpansionCast-in-Place
Adhesive Grouted
Covered by ACI 318-05
BondedMechanical
Not Covered by ACI 318-05
Screw4University of FloridaUniversity of Florida
Department of Civil EngineeringDepartment of Civil Engineering
Overview:Overview:• How today’s codes and standards work
together for selection of anchors:– Design– Product Approval
• Design and product approval considerations– Cast-in-Place– Post-Installed Mechanical– Bonded
5University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
What “Design” and “Product Approval” What “Design” and “Product Approval” Mean in Today’s Codes and Standards for Mean in Today’s Codes and Standards for
Anchorage to ConcreteAnchorage to Concrete• Design:
– Based on Strength (LRFD) design concepts– No more “Allowable Load” Tables– Requires the expertise of a Professional
Engineer• Product Approval
– Must be based on criteria that are “in-sync” with the design provisions
6University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
How Today’s Codes and Standards Work How Today’s Codes and Standards Work for Selection of Anchors:for Selection of Anchors:
Design and Product ApprovalDesign and Product Approval
• Cast-in-place anchors• Post-installed mechanical anchors• Screw anchors• Bonded anchors
– Adhesive anchors– Grouted anchors
R. A. Cook ACI Atlanta 2007 Hot Topic
2
7University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
CastCast--inin--Place AnchorsPlace Anchors
hef = Effective Embedment Depth
hef
8University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design of CastDesign of Cast--inin--Place AnchorsPlace Anchors
IBC 2006§1912
ACI 318-05§8.1.3
ACI 318-05Appendix D
9University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
IBCIBC––2006 Provisions2006 Provisions
10University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ACI 318ACI 318--05 Provisions05 Provisions
• Appendices are generally not mandatory• ACI 318 Chapter 8 “Analysis and Design –
General Considerations” §8.1.3 makes Appendix D mandatory:
8.1.3 — Anchors within the scope of Appendix D, Anchoring to Concrete, installed in concrete to transfer loads between connected elements shall be designed using Appendix D.
11University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for CastProduct Approval for Cast--inin--Place Place AnchorsAnchors
IBC 2006§1912
ACI 318-05§8.1.3
ACI 318-06Appendix D
§D.2.3
…
12University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for CastProduct Approval for Cast--inin--Place Place Anchors Anchors –– ACI 318ACI 318--06 Appendix D06 Appendix D
Lot’s of text but basically any standard headed anchor or hooked anchor will meet these requirements
…
R. A. Cook ACI Atlanta 2007 Hot Topic
3
13University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
CastCast--inin--Place Anchors:Place Anchors:Effects of CrackingEffects of Cracking
Headed AnchorsCurves in uncracked and cracked concrete
14University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
PostPost--Installed Mechanical AnchorsInstalled Mechanical Anchors::
Undercut AnchorsUndercut Anchors
Pre-DrilledUndercut
Cone Anchor Sleeve
TensileForce
15University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
PostPost--Installed Mechanical AnchorsInstalled Mechanical Anchors::
TorqueTorque--Controlled Expansion AnchorsControlled Expansion Anchors
(1) Heavy Duty (2) Wedge Fastener (3) Sleeve Fastener Sleeve Fastener
16University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
PostPost--Installed Mechanical Anchors: Installed Mechanical Anchors: DisplacementDisplacement--ControlledControlled
Expansion AnchorsExpansion Anchors
(1) Drop-In Fastener (2) Self-Drilling (3) Stud Fastener Fastener
17University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design of PostDesign of Post--Installed Installed Mechanical AnchorsMechanical Anchors
IBC 2006§1912
ACI 318-05§8.1.3
ACI 318-05Appendix D
18University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
IBCIBC––2006 Provisions2006 Provisions
R. A. Cook ACI Atlanta 2007 Hot Topic
4
19University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for PostProduct Approval for Post--Installed Mechanical AnchorsInstalled Mechanical Anchors
ACI 318-05§3.8.6
IBC 2006§1912
ACI 318-06Appendix D
§D.2.3
D.2.3 — Headed …. Post-installed anchors that meet the assessment requirements of ACI 355.2 are included. The suitability of the post-installed anchor for use in concrete shall have been demonstrated by the ACI 355.2 prequalification tests.
20University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ACI 318ACI 318--05 Appendix D05 Appendix D
• ACI 318 Chapter 3 “Materials” §3.8.6makes ACI 355.2-04 mandatory:
3.8.6 — “Qualification of Post-Installed Mechanical Anchors in Concrete (ACI 355.2-04)” is declared to be part of this code as if fully set forth herein, for the purpose cited in Appendix D.
21University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for PostProduct Approval for Post--Installed Installed Mechanical Anchors:Mechanical Anchors:
ACI 318ACI 318--06 Appendix D06 Appendix DD.2.3 — … Post-installed anchors that meet the assessment requirements of ACI 355.2 are included. The suitability of the post-installed anchor for use in concrete shall have been demonstrated by the ACI 355.2 prequalification tests.
ACI 355.2-04
22University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for PostProduct Approval for Post--Installed Mechanical Anchors:Installed Mechanical Anchors:
How this is currently implementedHow this is currently implemented
ICC ES AC193 ACI 355.2-04
ICC ESEvaluation
Report
23University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
PostPost--Installed Mechanical Anchors: Installed Mechanical Anchors: Screw AnchorsScrew Anchors
(not specifically covered by ACI 318(not specifically covered by ACI 318--05)05)
24University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design of PostDesign of Post--Installed Screw Installed Screw AnchorsAnchors
IBC 2006§104.11
ICC ES AC193 ACI 318-05Appendix D
R. A. Cook ACI Atlanta 2007 Hot Topic
5
25University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
IBCIBC--2006 Provisions2006 Provisions
26University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval of PostProduct Approval of Post--Installed Screw AnchorsInstalled Screw Anchors
IBC 2006§104.11
ICC ES AC193
ICC ESEvaluation
Report
27University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ICCICC--ES Evaluation ReportsES Evaluation Reports
“…having an evaluation report does not obligate the AHJ (Authority Having Jurisdiction) to approve the evaluated product. The report is simply technical evidence upon which the AHJ can approve the product if, on the job site, it is used within the report conditions. The approval decision lies with the AHJ.”
Ref.: “Code Approval”; The Basics, The Subtleties, and The Abuses www.icc-es.org
28University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Bonded AnchorsBonded Anchors-- Adhesive and Grouted Adhesive and Grouted (not covered by ACI 318(not covered by ACI 318--05)05)
AdhesiveHole diameter
≤ 1.5 anchor diameter
GroutedUnheaded Headed
Hole diameter > 1.5 times anchor diameter
29University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design and Product Approval of Design and Product Approval of PostPost--Installed Adhesive AnchorsInstalled Adhesive Anchors
IBC 2006§104.11
IBC-ES AC308Design and Product Approval
30University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design and Product Approval of Design and Product Approval of PostPost--Installed Grouted AnchorsInstalled Grouted Anchors
§104§104.11
Currently not covered by ICC-ES Acceptance Criteria
R. A. Cook ACI Atlanta 2007 Hot Topic
6
31University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ACI Consensus Standard StatusACI Consensus Standard Statuson Bonded Anchorson Bonded Anchors
• Adhesive anchor design provisions have been balloted by ACI 318 Sub B
• An adhesive anchor product approval standard is in the ACI 355 balloting process
• Grouted anchors need to be included• The goal is to have ACI consensus
standards issued by 2011.
32University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design and Product ApprovalDesign and Product ApprovalConsiderationsConsiderations
• Cast-in-place anchors• Post-installed mechanical anchors• Screw anchors• Bonded anchors
– Adhesive anchors– Grouted anchors
33University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
• ACI 318-05 Appendix D for Design– Basic design considerations
• ACI 355.2-04 for Product Approval– Previously presented by John Silva
Design and Product Approval of Design and Product Approval of CastCast--inin--Place and PostPlace and Post--Installed Installed
Mechanical AnchorsMechanical Anchors
34University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ACI 318ACI 318--05 APPENDIX D 05 APPENDIX D ––ANCHORING TO CONCRETEANCHORING TO CONCRETE
• Introduced in ACI 318-02• Developed by three ACI Committees
(318, 349, and 355) over more than ten years
• Applies to cast-in-place and post-installed mechanical anchors (some limitations)
35University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.2.2 D.2.2 -- SCOPESCOPE• Included:
– Cast-in-Place Anchors– Post-Installed Mechanical Anchors
• Excluded:– Specialty Inserts– Through Bolts– Multiple Anchors Connected to Single Plate
at the Embedded End of the Anchors– Adhesive & Grouted Anchors– Powder/Pneumatic Actuated Nails or Bolts
What is included and not included What is included and not included in ACI 318in ACI 318--05 Appendix D05 Appendix D
36University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.3.5 D.3.5 -- GENERAL REQUIREMENTSGENERAL REQUIREMENTS• Code formulas are valid for:
– fc′ ≤ 10,000 psi for cast-in anchors– fc′ ≤ 8000 psi for post-Installed
• Post-installed anchors in concrete with fc′ > 8000 psi must be tested
R. A. Cook ACI Atlanta 2007 Hot Topic
7
37University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D4.1.1 D4.1.1 -- STRENGTH OF ANCHORSSTRENGTH OF ANCHORS
φNn ≥ Nua (D-1)φVn ≥ Vua (D-2)
• Lowest φNn and φVn from applicable failure modes
• Interaction for combinations of Nuaand Vua
38University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.4.2 D.4.2 -- NOMINAL STRENGTHNOMINAL STRENGTH
• Design models in agreement with Test Results
• Based on 5% fractile of basic individual anchor strength– 90% confidence that 95% of actual
strengths will exceed nominal strength
39University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Lower Fractile Design ApproachLower Fractile Design Approach
5 % Fractile
Average (Mean) Statistical parameters
•Average (mean)•Standard deviation •Coefficient of variation•Number of samples
Tested Capacity
Freq
uenc
y
40University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5 D.5 -- DESIGN FOR TENSILE LOADINGDESIGN FOR TENSILE LOADING• D.5.1 – Steel Strength • D.5.2 – Concrete Breakout Strength• D.5.3 – Pullout Strength• D.5.4 – Concrete Side-Face Blowout
Strength of a Headed Anchor
41University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.1 D.5.1 -- STEEL STRENGTH (TENSION)STEEL STRENGTH (TENSION)
Nsa = nAsefuta (D-3)
where futa ≤ 1.9 fya
≤ 125,000 psi
Nn
42University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.2 D.5.2 -- CONCRETE BREAKOUT (TENSION)CONCRETE BREAKOUT (TENSION)
NnNn
R. A. Cook ACI Atlanta 2007 Hot Topic
8
43University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.2.1 D.5.2.1 -- CONCRETE BREAKOUT STRENGTH CONCRETE BREAKOUT STRENGTH OF ANCHOR GROUP (TENSION)OF ANCHOR GROUP (TENSION)
, , , , ( 5)Nccbg ec N ed N c N cp N b
Nco
AN N DA
ψ ψ ψ ψ= −
Accounts for post-installed anchorAccounts for cracking
Accounts for edge effectsAccounts for eccentricity
Accounts for projected area of failure surface
Basic single anchor strength
Consider Only Anchors in Tension44University of FloridaUniversity of Florida
Department of Civil EngineeringDepartment of Civil Engineering
D.5.2.1 D.5.2.1 -- PROJECTED AREA PROJECTED AREA AANoNo
hef
1.5hef
1.5hef
1.5hef
Plan ViewElevation
ANco = 9hef (D-6)
1.5hef
Nn1.5hef 1.5hef
2
≈350
45University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.2.1 D.5.2.1 -- PROJECTED AREA APROJECTED AREA ANN
c1 s1 1.5hef
1.5hef
c2
s2
ef1 h5.1s ≤
ef2 h5.1c ≤
NcoNc nAA ≤
ef2 h5.1s ≤
ef1 h5.1c ≤
46University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.2.2 D.5.2.2 -- BASIC CONCRETE BREAKOUTBASIC CONCRETE BREAKOUT
• Single Anchor in Tension in Cracked Concrete
(D-7)
- k = 24 for cast-in anchors- k =17 for post-installed anchors
(or higher value from ACI 355.2)
' 1.5b c efN k f h=
47University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.3 D.5.3 -- PULLOUT STRENGTH PULLOUT STRENGTH Npn = ψc,PNp (D-14)
• Headed Stud/BoltNp = 8Abrgfc
’ (D-15)
• J-Bolt or L-BoltNp = 0.9fc
’ehdo (D-16)where 3d0 ≤ eh ≤ 4.5d0
Npn
eh
• For post-installed mechanical anchors, Npmust be based on results of tests performed and evaluated per ACI 355.2
48University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.5.4 D.5.4 -- SIDESIDE--FACE BLOWOUTFACE BLOWOUT
• Headed anchor with deep embedment, close to edge (ca1 < 0.4hef )
'1160 (D-17)sb a brg cN c A f=
Nn
R. A. Cook ACI Atlanta 2007 Hot Topic
9
49University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6 D.6 -- DESIGN FOR SHEAR LOADINGDESIGN FOR SHEAR LOADING
• D.6.1 – Steel Strength• D.6.2 – Concrete Breakout Strength• D.6.3 – Concrete Pryout Strength
50University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6.1 D.6.1 -- STEEL STRENGTH (SHEAR)STEEL STRENGTH (SHEAR)
(a) Cast-in Headed Stud AnchorsVsa = nAsefuta (D-19)
(b) Cast-in Headed and Hooked Bolts, and Post-Installed Anchors
Vsa = nAse (0.6futa) (D-20)
where futa ≤ 1.9fya≤ 125,000 psi
With built-up grout pads, use 0.8Vsa
Vn
51University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6.2 D.6.2 -- CONCRETE BREAKOUT CONCRETE BREAKOUT (SHEAR)(SHEAR)
Vn
52University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6.2.1(b) D.6.2.1(b) -- CONCRETE BREAKOUT CONCRETE BREAKOUT STRENGTH OF ANCHOR GROUP (SHEAR)STRENGTH OF ANCHOR GROUP (SHEAR)
Basic single anchor strengthAccounts for cracking
Accounts for edge effectsAccounts for eccentricity
Accounts for projected area of failure surface
, , , ( 22)Vccbg ec V ed V c V b
Vco
AV V DA
ψ ψ ψ= −
53University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Front view
Vn
Edge of concrete
Plan view
Vn
hef
Side section
ca1
35o
1.5ca1 1.5ca1
1.5ca1
1.5ca1
1.5ca1AVco
AVco = 2 (1.5ca1) (1.5ca1)= 4.5(ca1)2 (D-23)
54University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
AVcca1
1.5ca1 1.5ca1s1
Vn
ha
AVc = (2 x 1.5ca1 + s1)ha
If ha < 1.5ca1 and s1 < 3ca1
R. A. Cook ACI Atlanta 2007 Hot Topic
10
55University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6.2 D.6.2 -- BASIC CONC. BREAKOUT (SHEAR)BASIC CONC. BREAKOUT (SHEAR)• Single anchor in shear in cracked concrete
• If anchors are rigidly welded to attachment
( )0.2
1.5'17 (D-24)e
b o c ao
V d f cd
⎛ ⎞= ⎜ ⎟
⎝ ⎠
( )0.2
1.5'18 (D-25)e
b o c ao
V d f cd
⎛ ⎞= ⎜ ⎟
⎝ ⎠
56University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.6.3 D.6.3 -- CONCRETE PRYOUTCONCRETE PRYOUTSingle Anchor Vcp = kcpNcb (D-29)Group of Anchors Vcpg = kcpNcbg (D-30)
where• kcp = 1.0 for hef < 2.5 in.• kcp = 2.0 for hef ≥ 2.5 in.• Ncb computed from Eq. (D-4)• Ncbg computed from Eq. (D-5)
Vn
57University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.7 TENSION/SHEAR INTERACTIOND.7 TENSION/SHEAR INTERACTION
2.1VV
NN
n
ua
n
ua =+φφ
0.1V
VN
N 35
n
ua35
n
ua =⎟⎠
⎞⎜⎝
⎛+⎟
⎠
⎞⎜⎝
⎛
φφ
Nu
φ Nn
0.2φNn
0.2φVn φVnVu
58University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
D.8 D.8 -- PRECLUDE SPLITTING FAILUREPRECLUDE SPLITTING FAILURE• At Design Stage, Specific Products May not
be Known• In Absence of Reinforcement for Crack
Control, D.8 Sets Minimum Cover, Spacings, Member Thickness
• Lesser Values are Permitted per ACI 355.2
Nn Nn
NnNn
59University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval for PostProduct Approval for Post--Installed Installed Mechanical AnchorsMechanical Anchors
ACI 355.2ACI 355.2--0404
• Testing Requirements in Uncracked Concrete, and in Cracked Concrete– Identification Tests– Reference Tests– Reliability Tests– Service-Condition Tests
60University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ACI 355.2
Sample Format
R. A. Cook ACI Atlanta 2007 Hot Topic
11
61University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
• ICC-ES AC308 for Design– Adhesive anchor design considerations
• ICC-ES AC308 for Product Approval– Adhesive anchor product approval tests
• Grouted anchors are currently not covered by ICC-ES AC308
Today’s Design and Product Today’s Design and Product Approval of Bonded AnchorsApproval of Bonded Anchors
62University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
• The following presents background information on behavior, design and product approval of bonded anchors
• Specific design requirements for adhesive anchors are now in ICC-ES AC308 and being balloted by ACI 318
• Specific product approval requirements for adhesive anchors are in ICC-ES AC308 and being balloted by ACI 355
• Grouted anchors are currently not covered by ICC-ES AC308
Background on Behavior, Design, and Background on Behavior, Design, and Product Approval of Bonded AnchorsProduct Approval of Bonded Anchors
63University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
How Bonded Anchors Transfer How Bonded Anchors Transfer Tension LoadsTension Loads
hef
NN
Threaded Rod Mortar Concrete
τ τ0
hef
NN
Threaded Rod Mortar Concrete
τ τ0
Eligehausen et. al., 2004
64University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Potential Embedment Failure Potential Embedment Failure Modes of Bonded Anchors Modes of Bonded Anchors
Cook et al, 1998
65University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Bond Failure at Steel/Mortar Interface Bond Failure at Steel/Mortar Interface (Grout or Adhesive)(Grout or Adhesive)
The presence of the shallow cone has been shown to be secondary, the strength is dependent on bond
66University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Bond Strength of Single Bonded AnchorBond Strength of Single Bonded AnchorUniform Bond Stress ModelUniform Bond Stress Model
bond efN d hτ π=τ
Nbond
hef
d
R. A. Cook ACI Atlanta 2007 Hot Topic
12
67University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Comparison of loads with the uniform bond modelComparison of loads with the uniform bond model(data set average bond stress normalized to 10 (data set average bond stress normalized to 10 MPaMPa))
0
100
200
300
400
500
600
0 10000 20000 30000 40000 50000 60000
Load
(KN
)
measured loadsmean - uniform bond model5% fractile - uniform bond model
Bond Area (A b ) (mm2)
Only 17 of 891 data points below 5% fractile (1.9%)
Cook et al, 1998
68University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Grouted Anchor Failure ModesGrouted Anchor Failure Modes
Bond Failure atGrout/Concrete Interface
(with or without head)
Concrete Breakout Failure
Zamora et al 2003
69University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Bond Strength Considerations for Bond Strength Considerations for Grouted AnchorsGrouted Anchors
τh ef
d
τ0hef
d0
τ0
d0
h ef
Bond failure at steel/grout interface
Bond failure at grout/concrete interface
Zamora et al 2003
70University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Bonded Strength Considerations Bonded Strength Considerations for Bonded Anchorsfor Bonded Anchors
• For adhesive anchors (d≤1.5d0), the bond strength can be based the nominal bond stress relative to the anchor diameter (τ)
• For grouted anchors (d>1.5d0), the bonsstrength needs to consider both the nominal bond stress at the anchor/grout interface (τ) and at the grout/concrete interface (τ0)
71University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Design of Bonded AnchorsDesign of Bonded Anchors
• Bond strength can be based on the uniform bond stress model up to hef/d of ~20.
• Strength is limited to the concrete breakout strength as provided in ACI 318-05 Appendix D
72University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Behavior of Bonded AnchorsBehavior of Bonded Anchors
Anchor diameter (d)
Tens
ion
Load
' 1.5c efN k f h=
efN d hτ π=
Bond failure Concrete breakout failure
R. A. Cook ACI Atlanta 2007 Hot Topic
13
73University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Critical Spacing and Edge Distance Critical Spacing and Edge Distance for Bonded Anchorsfor Bonded Anchors
0.5 scrs1
s2
ca1
ca2
AN = (ca1 + s1 + 0.5 scr)(ca2 + s2 + 0.5 scr)if ca1 and ca2 < 0.5 scrand s1 and s2 < scr
0.5 scr
0.5
s cr
0.5
s cr
2cr0N sA =
0.5
s cr
0.5 scr
a) Single anchor away from edges and other anchors
b) Four anchor group with close spacing and located near a corner
0.5 scrs1
s2
ca1
ca2
AN = (ca1 + s1 + 0.5 scr)(ca2 + s2 + 0.5 scr)if ca1 and ca2 < 0.5 scrand s1 and s2 < scr
0.5 scr
0.5
s cr
0.5
s cr
2cr0N sA =
0.5
s cr
0.5 scr
a) Single anchor away from edges and other anchors
b) Four anchor group with close spacing and located near a corner
74University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Critical spacing and edge distanceCritical spacing and edge distance
Cast-in-place and post-installed mechanical anchors:
Bonded anchors:
2 3.0cr cr efs c h= =
Why the difference?
0.5
2 201450cr crs c d τ⎛ ⎞= = ⎜ ⎟⎝ ⎠
Eligehausen et al 2006
ACI 318-05 Appendix D
75University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
For bond failure, embedment length For bond failure, embedment length does not have the same effect as that does not have the same effect as that for postfor post--installed mechanical anchors installed mechanical anchors
N
N
hef =20d
hef=10d
Appl and Eligehausen 2005
76University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
For bond failure, bond strength has a For bond failure, bond strength has a significant influence on critical spacingsignificant influence on critical spacing
1390 psi [9.9 MPa]τ =
2850 psi [19.6 MPa]τ =
Appl and Eligehausen 2005
77University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Strength of Bonded Anchors:Strength of Bonded Anchors:
, , ,0
Ncbond group ec N g N bond
Nc
AN NA
ψ ψ=
bond efN d hτ π=0.5
2 201450cr crs c d τ⎛ ⎞= = ⎜ ⎟⎝ ⎠
But not greater than the concrete breakout strength calculated by ACI 318-05 Appendix D Eq. (D-5)
Eligehausen et al 2006
78University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Product Approval Standard:Product Approval Standard:Factors Influencing Bonded Anchor StrengthFactors Influencing Bonded Anchor Strength
• basic bond strength
• temperature
• long term strength (creep)
• loading after short term cure
• Improperly cleaned holes
• mixing method (bulk products)
• damp hole installation
• submerged installation
• hole orientation
• freeze/thaw
• fire resistance
• durability
• cracked concrete
• etc., etc….
R. A. Cook ACI Atlanta 2007 Hot Topic
14
79University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Example: Relative Bond Stress ComparisonExample: Relative Bond Stress ComparisonAdhesive and GroutedAdhesive and Grouted
1800
2342
1659
2259
1780
2850
2663
447
793
1631
2227
1450
2314
1627
2480
2013
2564
334
1656
2104
3055
3040
2306 25
7928
7225
86
2901
2946
1063
0
1000
2000
3000
4000
A B C D E F G H I J K L M N O P Q R S T 1 2 3 4 5 6 7 8 9Product
Ave
rage
Uni
form
Bon
d St
ress
, [ps
i] Adhesive τ mean = 1850 psiGrouted τ mean = 2594 psi
80University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Example: Influence of Hole MoistureExample: Influence of Hole Moisture
0
5
10
15
20
25
30
35
A B C D E F G H I J K L M N O P Q R S T
Aver
age
Uni
form
Bon
d St
reng
th, M
Pa
DRY HOLE (BASELINE)
DAMP HOLE
WET HOLE
Cook and Konz 2001
81University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Example: Influence of Cracked ConcreteExample: Influence of Cracked Concrete
Meszaros, J. (2001)
82University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
ICC-ESAC308SampleFormat
83University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Summary: How today’s codes and Summary: How today’s codes and standards work together for selection of standards work together for selection of
anchors:anchors:• Cast-in-place
Design: IBC 2006 – ACI 318-05Product Approval: ACI 318-05
• Post-Installed MechanicalDesign: IBC 2006 – ACI 318-05Product Approval: IBC 2006 – ACI 318-05 – ACI 355.2-04 via ICC-ES AC193
84University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Summary: How today’s codes and Summary: How today’s codes and standards work together for selection of standards work together for selection of
anchors (continued):anchors (continued):• Post-Installed Screw Anchors
Design: IBC 2006 – ICC-ES AC193 – ACI 318-05Product Approval: IBC 2006 – ICC-ES AC193
• Adhesive Bonded AnchorsDesign: IBC 2006 – ICC-ES AC308Product Approval: IBC 2006 – ICC-ES AC308
• Grouted AnchorsIBC 2006 – Tests must be performed
R. A. Cook ACI Atlanta 2007 Hot Topic
15
85University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Summary: Design and Product Summary: Design and Product Approval ConsiderationsApproval Considerations
• Cast-in-place anchorsCovered by ACI 318-05
• Post-installed mechanical anchorsCovered by ACI 318-05 and ACI 355.2-04
• Post-Installed screw anchorsCovered by IBC 2006 via ICC-ES AC193 but needs to be addressed by ACI 318 and ACI 355
86University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
Summary: Design and Product Summary: Design and Product Approval Considerations (continued)Approval Considerations (continued)
• Adhesive bonded anchorsCovered by IBC 2006 via ICC-ES AC308 and now being addressed by ACI 318 and ACI 355
• Grouted bonded anchorsCovered indirectly by IBC 2006 but need to addressed by ACI 318 and ACI 355
• Bottom Line on Bonded AnchorsAll glues are not created equal
87University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
AcknowledgementsAcknowledgements• Richard Klingner - University of Texas• Basile Rabbat – PCA• Don Meinheit - Wiss, Janney, Elstner
Associates., Inc.• Rolf Eligehausen, Werner Fuchs, and Jörg Appl
- University of Stuttgart• John Silva and Richard Wollmershauser – Hilti• ACI 355 and ACI 318 Sub B
88University of FloridaUniversity of FloridaDepartment of Civil EngineeringDepartment of Civil Engineering
The End
ANCHORAGE TO CONCRETEANCHORAGE TO CONCRETE-- SELECTION AND DESIGNSELECTION AND DESIGN