2013-10-17 Seaoc Ssdm Series Ppt Vol 1 Handout

Structural Engineers Associa1on of California Webinar: 2012 IBC SSDM – Volume 1 – Code Applica=on Examples

October 17, 2013 Page 1

Ryan A. Kersting, S.E., Volume Manager & Presenter Buehler & Buehler Structural Engineers, Inc.

Structural Engineers Association of California

The 2012 IBC SEAOC Structural Seismic Design Manual

Introduction to the 2012 Edition: •  Expanded scope

–  5 Volumes •  Examples based on latest standards •  Application of SEAOC Blue Book

recommendations illustrated •  More elements and systems addressed

–  Collectors –  Diaphragms –  Base plates

–  Isolation –  Supplemental damping

2



The 2012 IBC SEAOC Structural Seismic Design Manual

3

Authors / Reviewers / Contributors •  Ryan A. Kersting, S.E., Buehler & Buehler Structural

Engineers •  April Buchberger, S.E., Clark Pacific •  Timothy S. Lucido, S.E., Rutherford + Chekene •  Kevin Morton, S.E., Hohbach-Lewin Structural Engineers •  Nicolas Rodrigues, S.E., DeSimone Consulting Engineers •  Ali Sumer, Ph.D., S.E., State of California Office of

Statewide Health Planning and Development (OSHPD) •  Additional contributions from members of SEAOC

Seismology Committee and Subcommittees

Volume 1 Acknowledgements

4



Ryan A. Kersting, S.E., Volume Manager & Presenter Buehler & Buehler Structural Engineers, Inc.

Structural Engineers Association of California

Learning Objectives

•  Become familiar with changes in seismic provisions of: –  2012 International Building Code (IBC) - Chapter 16 –  American Society of Civil Engineers (ASCE) - Minimum

Design Loads for Buildings and Other Structures ASCE/SEI 7-10 (ASCE 7-10)

–  2013 California Building Code (CBC) - Chapter 16A •  Learn to use Volume 1 of the 2012 IBC SEAOC

Structural Seismic Design Manual (SSDM)

6



Learning Objectives

•  Learn overall approach to implementing specific seismic provisions of 2012 IBC / ASCE 7-10, including those pertaining to: –  Design Spectral Response Acceleration Parameters –  Site-specific Ground Motion Procedures –  Combinations of Structural Systems –  Configuration Irregularities / Discontinuous Systems –  Scaling Results of Modal Response Spectrum Analysis –  Wall and Anchorage Design for Out-of-Plane Forces

7

•  Introduction to SSDM Volume 1 •  Seismic code changes relevant to Vol. 1

–  2012 IBC Chapter 16 –  ASCE 7-10 Chapters 11 and 12 –  2013 CBC Chapter 16A

•  Selected Examples •  Questions

Volume 1 Presentation Overview

8



PART 1 – INTRODUCTION Volume 1 Scope, Purpose, Reference Standards, Contents, Organization, and Format

Scope / Purpose of SSDM (all volumes): •  Intent of examples is to illustrate a design

approach engineered to achieve good performance under severe seismic loading, including some SEAOC recommendations for exceeding minimum code requirements in order to achieve that performance

Introduction to SSDM Volume 1

10



Scope / Reference Standards for Vol. 1: •  2012 IBC −  Seismic provisions within Chapter 16 −  Refers to ASCE 7-10 for most provisions

•  ASCE 7-10 −  Chapters 11 (with ref. to 21 & 22), 12, 13, and 15 −  Primary focus on Chapter 12

•  SEAOC Blue Book


11

Contents: •  Examples illustrate application of specific

section or provision within ASCE 7-10 −  Some re-written to reflect changes to code

provisions & SEAOC recommendations −  Others cover new topics or new approaches not

previously addressed −  Increased consistency with and reference to

SEAOC Blue Book −  Application of material design standards is covered

in Volumes 2, 3, and 4


12



Contents (cont.): •  58 total examples distributed across ASCE

7-10 as follows: −  Chapter 11 Seismic Design Criteria – 4 −  Chapter 12 Seismic Design Requirements for

Building Structures – 45 −  Chapter 13 Seismic Design Requirements for

Nonstructural Components – 5 −  Chapter 15 Seismic Design Requirements for

Nonbuilding Structures – 4


13

Contents (cont.): •  Examples distributed across ASCE 7-10

Chapter 12 as follows: −  §12.1 Structural Design Basis - 1 −  §12.2 Structural System Selection - 5 −  §12.3 Irregularities & Redundancy - 16 −  §12.4 Seismic Load Effects / Combos - 2 −  §12.7 Modeling Criteria - 1 −  §12.8 Equivalent Lateral Force Procedure - 7


14



Contents (cont.): •  Examples distributed across ASCE 7-10

Chapter 12 as follows (cont.): −  §12.9 Modal Response Spectrum Analysis - 1 −  §12.10 Diaphragms - 3 −  §12.11 Structural Walls and Anchorage - 3 −  §12.12 Drift and Deformation - 3 −  §12.13 Foundation Design - 2 −  §12.14 Simplified Design Procedure - 1


15

Organization / Format: •  Examples are organized in same order as

ASCE 7 provision(s) being addressed •  Each problem statement provides detailed

“given” information followed by list of items to determine in order to arrive at the solution

•  Most examples contain introductory overview and/or additional commentary after solution


16



PART 2 – SEISMIC CODE CHANGES 2012 IBC Chapter 16 ASCE 7-10 Chapters 11 and 12 2013 CBC Chapter 16A

2012 IBC Chapter 16: •  Section 1604.5 Risk Category

–  “Risk Category” replaces former “Occupancy Category” terminology

– Table 1604.5 maintains I, II, III, and IV classifications with some minor revisions within table •  NOTE: ASCE 7 Table 1.5-1 also addresses Risk

Category, but IBC Table 1604.5 should be used as IBC language is more specific and governs

– CBC Table 1604A.5 is similar with subtle differences

Seismic Code Changes

18



2012 IBC Chapter 16 (cont.): •  Section 1605 Load Combinations

– Load combinations with seismic load including overstrength are included by reference to applicable ASCE 7 provisions but not reprinted •  Text added to clarify how the ASCE combinations

with overstrength replace IBC combinations •  Subtle but significant improvement


19

2012 IBC Chapter 16 (cont.): •  Section 1613 Earthquake Loads

– Refers to ASCE 7-10 for earthquake effects (no change) •  “in accordance with ASCE 7, excluding Chapter 14

and Appendix 11A” –  IBC alternatives / revisions to ASCE 7 are

very limited (see §1613.4) •  Most 2009 IBC alternatives / revisions to ASCE

7-05 were incorporated into ASCE 7-10 •  CBC amendments in §1616A discussed later


20



2012 IBC Chapter 16 (cont.): •  Section 1613 Earthquake Loads

– Re-prints much of ASCE 7 Chapter 11 for determining: •  Ground motion values (including “new” maps from

ASCE 7 Ch. 22) – More on this later

•  Seismic Design Category (SDC)


21

ASCE 7-10 Chapter 11: •  Section 11.4 Seismic Ground Motion Values

– Refers to maps in Chapter 22 –  Introduces new term “Risk-Targeted Maximum

Considered Earthquake” (MCER) which is incorporated in the “new” ground motion maps


22



ASCE 7-10 Chapter 11 (cont.): •  Section 11.4 Seismic Ground Motion Values

–  “New” (ASCE 7-10) ground motion maps reflect four significant changes (USGS “Project 07”): 1.  USGS updates (seismic sources and NGA) 2.  Risk-targeted ground motion 3.  Maximum-direction ground motion 4.  Modified deterministic ground motion


23


–  “New” (ASCE 7-10) ground motion maps reflect four significant changes (USGS “Project 07”): 1.  USGS updates •  Incorporates 2008 USGS data for seismic sources/

models and next-generation attenuation (NGA) relationships

•  This factor by itself generally decreases ground motion parameters in many parts of U.S.


24




–  “New” (ASCE 7-10) ground motion maps reflect four significant changes (USGS “Project 07”): 2.  Risk-targeted ground motion •  Fundamental shift in ground motion basis from

“uniform hazard” (2% probability of exceedance in 50 years) to “uniform risk” (1% probability of collapse in 50 years) based upon generic structural fragility

•  Significant decrease in ground motion for New Madrid zone and Charleston, S.C.; otherwise < ±15% change


25


–  “New” (ASCE 7-10) ground motion maps reflect four significant changes (USGS “Project 07”): 3.  Maximum-direction ground motion •  Change from “geo-mean” calculation to use of the

acceleration in the direction of maximum response •  Increases short-period accelerations by factor of 1.1

and long-period accelerations by factor of 1.3


26




–  “New” (ASCE 7-10) ground motion maps reflect four significant changes (USGS “Project 07”): 4.  Modified deterministic ground motion •  Certain areas governed by “deterministic cap” (many

areas of California) •  Deterministic MCE formulation changed to 84th

percentile, or from 1.5x to 1.8x median characteristic earthquake ground motion


27


– Additional resources regarding this change: •  2007 SEAOC Convention paper by Luco, et. al.

(www.seaoc.org/bookstore, search “Proceedings”) •  EERI Seminar “Project 07-Reassessment of Seismic

Design Procedures and Development of New Ground Motions for Building Codes” (www.eeri.org/products-page/technical-seminars)


28




– What is net effect of “new” ground motion maps? •  Depends on location, but in general:

–  SS values in central and eastern U.S. have generally decreased by 10% - 25% compared to ASCE 7-05 values

–  SS values in western U.S. generally within ±15% of ASCE 7-05 values, although some areas have significantly higher increase

–  S1 values across most of U.S. generally within ±15% of ASCE 7-05 values, although some western U.S. areas show higher increase


29

From EERI “Project 07…” Seminar by Kircher, Luco, & Whittaker

Seismic Code Changes – Comparison of Ground Motion Values

30





31



32





33

ASCE 7-10 Chapter 12: •  §12.2.3.1 R, Ω0, & Cd for vertical combination

–  If lower system has lower R value: •  Permitted to use R, Ω0, & Cd of upper system for

design of upper system (but not as separate upper structure)

•  R, Ω0, & Cd of lower system shall be used for design of lower system (but not as separate lower structure)

–  ASCE 7-05 required that Ω0 & Cd values could not decrease for design of lower system

•  Different than two-stage analysis (see §12.2.3.2)


34




–  If upper system has lower R value: •  R, Ω0, & Cd of upper system shall be used for design

of both systems –  ASCE 7-05 required similar treatment of R (cannot increase

as go down the structure)

– SSDM Vol. 1 Design Examples 7 and 9


35


– 2013 CBC §1616A.1.5 replaces ASCE 7-10 language with language from ASCE 7-05: •  Value of R used for design within a story shall not

exceed lowest value of R in any story above •  Value of Ω0 & Cd used for design within a story shall

not be less than largest value of each in any story above


36



ASCE 7-10 Chapter 12: •  §12.2.3.2 Two Stage Analysis Procedure

– Allows analysis of upper and lower portions as separate structures if certain conditions are met •  Only change is new criteria item ‘e’ that upper may be

analyzed with ELF or MRSA procedure, but lower must be analyzed with ELF procedure

– 2013 CBC §1616A.1.6 adds item ‘f’ such that: •  Where design of upper elements is governed by

special seismic load combos, then those special loads must be considered in design of lower portion


37

ASCE 7-10 Chapter 12: •  §12.3.2 Irregular & Regular Classification

– T12.3-1 Horizontal Structural Irregularities •  Torsional Irregularity Types 1a and 1b

– Definitions improved by specifying accidental torsion for this check only needs to consider case with Ax = 1.0 (no iteration)

•  Nonparallel System Irregularity Type 5 – Definition improved by deleting “or not symmetric about” such

that irregularity only occurs if systems are not parallel

– SSDM Vol. 1 Design Examples 11 – 16 address horizontal irregularities


38



ASCE 7-10 Chapter 12: •  §12.3.2 Irregular & Regular Classification

– T12.3-2 Vertical Structural Irregularities •  In-Plane Discontinuity Irregularity Type 4

– Definition improved such that irregularity exists when in-plane offset such that overturning demands are placed on supporting beam, column, truss, or slab (rather than being based on amount of offset versus length of system)

– SSDM Vol. 1 Design Examples 17 – 23 address vertical irregularities


39

ASCE 7-10 Chapter 12: •  §12.8.1.1 Calculation of Cs

– Minimum base shear equation 12.8-5: •  Cs = 0.044SDSIe ≥ 0.01 •  Incorporated from ASCE 7-05 Supplement No. 2 •  Need not be considered for computing drift per

§12.8.6.1


40



ASCE 7-10 Chapter 12: •  §12.9.4 Scaling Design Values from Modal

Response Spectrum Analysis (MRSA) results – §12.9.4.1 Scaling of Forces:

•  If the combined response for the modal base shear (Vt) is less than 85% of the calculated equivalent lateral force (ELF) base shear (V), then forces shall be multiplied by (0.85V)/(Vt)


41


Response Spectrum Analysis (MRSA) results – §12.9.4.2 Scaling of Drifts:

•  If the combined response for the modal base shear (Vt) is less than 0.85CsW, where Cs is per Eq. 12.8-6, then drifts shall be multiplied by (0.85CsW)/(Vt) in addition to being multiplied by Cd / Ie per §12.9.2

– Otherwise, drifts need not be scaled beyond per §12.9.2

– SSDM Vol. 1 Design Example 37 (new)


42




Response Spectrum Analysis (MRSA) results – 2013 CBC §1616A.1.13 replaces ASCE §12.9.4

with: •  Modal base shears used to determine forces and drifts

shall not be less than those calculated per the equivalent lateral force procedure of §12.8


43

ASCE 7-10 Chapter 12: •  §12.10.2.1 Collectors Requiring Overstrength

Load Combinations for SDC C through F – Collectors shall be designed to resist load

combinations including the maximum of: •  Ω0QE, where QE is from V per §12.8 or §12.9 •  Ω0QE, where QE is from Fpx per §12.10 Eq. 12.10-1 •  QE, where QE is from Fpxmin per §12.10 Eq. 12.10-2 •  Exceptions…

–  (1) limitation of maximum relative to Fpmax (see next slide) –  (2) no Ω0 required for light-frame shear wall structures


44



ASCE 7-10 Chapter 12: •  §12.10.2.1 Collectors Requiring Overstrength

Load Combinations for SDC C through F – Collectors shall be designed to resist… max of:

•  Exception 1 limits maximum based on Fpmax: –  ASCE 7-10 limits maximum to QE, where QE is from Fpxmax

per §12.10 Eq. 12.10-3, but intent is being debated by multiple committees (SEAOC, ASCE, BSSC PUC, etc.)

–  2013 CBC §1616A.1.14 limits maximum to Ω0QE, where QE is from Fpxmax per §12.10 Eq. 12.10-3

– Recommend using CBC basis for ALL projects until clarified


45

ASCE 7-10 Chapter 12: •  §12.11.2.1 Wall Anchorage Forces

– Revised such that only one equation is used, with a new variable to account for diaphragm rigidity / flexibility •  Fp = 0.4SDSkaIeWp (Eq. 12.11-1) > 0.2kaIeWp

where: –  ka = 1.0 + (Lf / 100) ≤ 2.0 –  Lf = span (in feet) of flexible diaphragm between vertical

elements of LFRS; use Lf = 0 for rigid diaphragm

•  ka = 1.0 for rigid, = 2.0 max for flexible


46



ASCE 7-10 Chapter 12: •  §12.11.2.1 Wall Anchorage Forces

– Where anchorage is not at roof and where all diaphragms are not flexible, Fp from Eq. 12.11-1 may be multiplied by (1 + 2z/h)/3 where: •  z is height of anchor above the base of structure •  h is height of the roof above the base

– SSDM Vol. 1 Design Examples 41 – 43


47

ASCE 7-10 Chapter 12: •  §12.12.3 Structural Separation

– 2012 IBC incorporates 2009 IBC revisions to ASCE 7-05 •  Defines δM = Cdδmax/Ie

–  2013 CBC 1616A.1.15 defines δM = Cdδmax (provides additional separation for higher risk category structures)

•  Adjacent structures on same property shall be separated by δMT based on SRSS of δM1 and δM2

•  Structures shall be setback from property line by minimum of δM


48



ASCE 7-10 Chapter 12: •  §12.12.4 Members Spanning Between

Structures (new section) – Connections shall be designed for maximum

anticipated relative displacements, including: •  Multiplying calculated deflections (Cdδxe/Ie) by 1.5R/Cd

•  Considering diaphragm rotations, including torsional amplification if either structure is torsionally irregular

•  Considering diaphragm deformations •  Assuming structures are moving in opposite directions

and using absolute sum of displacements


49

PART 3 – SELECTED EXAMPLES DE1 – Design Spectral Response Acceleration Parameters DE3 – Site-Specific Ground Motion Values DE9 – Combination Framing Detailing DE24 – Elements Supporting Disc. Systems DE37 – Scaling Modal Resp. Spectrum Results DE42 – Out-of-plane Effects on 2-story Wall Panel



Design Spectral Response Acceleration Parameters •  Given a site location and soil Site Class •  Determine:

–  Mapped MCER parameters: SS and S1 –  Site Coefficients: Fa and Fv –  MCER parameters adjusted for site class: SMS and SM1 –  Design Spectral Acceleration Parameters: SDS and SD1

Design Example 1 – §11.4

51

Design Spectral Response Acceleration Parameters •  Mapped MCER parameters: SS and S1

–  “U.S. Seismic Design Maps” application available from USGS website (if accessible): http://geohazards.usgs.gov/designmaps/us/application.php

•  Choose applicable code: 2012 IBC or ASCE 7-10 •  Input address or latitude and longitude •  Input site class (will calculate site coefficients) •  Input risk category (although it doesn’t affect results) •  Output will include:

–  SS and S1 , Fa and Fv , SMS and SM1 , and SDS and SD1


52



Design Spectral Response Acceleration Parameters •  Mapped MCER parameters: SS and S1

–  OR, spreadsheet of data points based on latitude and longitude or maximum values by county or zip code from USGS or skghoshassociates.com (in upper right corner)

•  Obtain SS and S1 •  Determine Fa and Fv from Tables 11.4-1 and 11.4-2 •  Calculate SMS and SM1:

–  SMS = FaSS –  SM1 = FvS1

•  Calculate SDS and SD1: –  SDS = (2/3)SMS –  SD1 = (2/3)SM1


53

Site-Specific Ground Motion Procedures •  Given:

–  Calculated SDS and SD1 from mapped MCER SS and S1 –  Site-specific MCER and Design Response Spectra

•  Determine: –  Design response spectrum per §11.4.5 (map-based) –  Scaled site-specific design response spectrum per §21.3 –  Design acceleration parameters per §21.4

Design Example 3 – §11.4.7

54



Site-Specific Ground Motion Procedures •  Design response spectrum per §11.4.5

–  Determined based on calculated SDS and SD1 from mapped MCER SS and S1 in conjunction with §11.4.5 and Fig. 11.4.1


55

Site-Specific Ground Motion Procedures •  Scaled site-specific design response spectrum per

§21.3 –  Design spectral response acceleration at any period

shall not be taken less than 80% of Sa determined in accordance with §11.4.5

•  Sa (scaled s-s) ≥ 80% Sa (mapped)


56



Site-Specific Ground Motion Procedures •  Scaled site-specific design response spectrum per §21.3


57

Site-Specific Ground Motion Procedures •  Design acceleration parameters per §21.4

–  SDS = greatest of: •  site-specific Sa at T = 0.2 sec •  90% of largest site-specific Sa at any T > 0.2 sec •  80% of SDS per Section 11.4.4

–  SD1 = greatest of: •  site-specific Sa at T = 1.0 sec •  two times (2x) site-specific Sa at T = 2.0 sec •  80% of SD1 per Section 11.4.4

–  Refer to §21.4 for rules regarding use of these values •  Note: mapped S1 still required to be used in Eq. 12.8-6


58



Combination Framing Detailing Requirements •  §12.2.4 requires structural members common to

different framing systems to be designed using the detailing requirements for the system with the highest value of R

•  Given a two-story steel special moment-resisting frame (SMRF, R = 8, Ω0 = 3) supported by a one-story special concrete shear wall (R = 5, Ω0 = 2.5)

•  Determine the design axial force and detailing requirements for the concrete pilasters supporting the steel SMRF columns


59

Combination Framing Detailing Requirements


60



Combination Framing Detailing Requirements •  Design axial force for concrete pilaster:

–  Since common to both the steel SMRF and the concrete shear wall, pilaster must be designed using requirements for SMRF (higher R factor)

–  Design axial force on steel SMRF columns must include amplified seismic loads (combinations including Ω0) when loads exceed a certain threshold

•  Assuming this is the case, concrete pilaster would need to be designed using the same load combinations and with Ω0 = 3.0

–  SEAOC Seismology Blue Book article recommends capacity-based approach as illustrated in SSDM


61

Combination Framing Detailing Requirements •  Detailing requirements for concrete pilaster:

–  Concrete pilaster shall be detailed in accordance with special concrete shear wall provisions at a minimum

•  Special “boundary zone” requirements would effectively provide equivalent performance to SMRF detailing

•  For more information, refer to SEAOC Seismology Blue Book article "Structural Detailing for Combined Structural Systems" available at: http://www.seaoc.org/bluebook/index.html


62



Elements Supporting Discontinuous Systems •  Example provides a specific worked-out solution

but also includes commentary with considerations for other common configurations

•  New suggestion from SEAOC Seismology regarding design of “transfer diaphragm” in out-of-plane offset configuration

Design Example 24 – §12.3.3.3

63

Elements Supporting Discontinuous Systems


64



Elements Supporting Discontinuous Systems •  §12.3.3.3 requires elements supporting

discontinuous systems to be designed to resist special load combinations including overstrength

•  §12.10.1.1 and §12.10.2.1 require transfer forces to be considered in design of diaphragms and collectors, respectively –  intent is being debated by multiple committees

(SEAOC, ASCE, BSSC PUC, etc.)


65

Elements Supporting Discontinuous Systems •  SEAOC Seismology Committee suggests the

engineer apply the special load combinations to the transfer diaphragm when the performance of the diaphragm is critical to the performance of the primary LFRS


66



Scaling Modal Response Spectrum Analysis Results •  Given the following:

–  Fundamental geometry and weight data for the structure –  Design response spectrum from either §11.4.5 or §21.3 –  Mapped value of S1 –  Seismic Importance Factor, Ie

–  Value of R, Cd, Ta, Cu, and Tcalc in each orthogonal direction (x and y)


67

Scaling Modal Response Spectrum Analysis Results •  Determine the following:

–  Combined modal response design base shear Vt in each orthogonal direction using MRSA per 2012 IBC

–  Scaling of seismic forces from MRSA results per 2012 IBC

–  Scaling of drifts from MRSA results per 2012 IBC –  Scaling of seismic forces and drifts from MRSA results

per 2013 CBC


68



Scaling Modal Response Spectrum Analysis Results •  Combined modal response design base shear Vt in

each direction per 2012 IBC (cont.): –  §12.9.1 - Build analysis model for modal analysis with

enough modes such that modal mass participation is at least 90% of actual mass in each orthogonal direction

–  §12.9.2 - Perform MRSA with design response spectrum in each direction divided by (R/Ie). Further multiply drift and displacement results by (Cd/Ie)

–  §12.9.3 - Obtain combined response for each parameter of interest, including base shear Vt in each direction, using appropriate modal combination procedure


69

Scaling Modal Response Spectrum Analysis Results •  Scaling of seismic forces from MRSA results per

2012 IBC: –  §12.9.4 - Determine the base shear V in each orthogonal

direction using the procedures in §12.8 with the calculated fundamental period (Tcalc from MRSA)

–  §12.9.4.1 - For scaling of forces, if Tcalc > CuTa, use CuTa in §12.8 base shear calcs.

–  §12.9.4.1 - If Vt < 85%V, force results shall be multiplied by: (0.85V)/(Vt)


70



Scaling Modal Response Spectrum Analysis Results •  Scaling of seismic drifts from MRSA results per

2012 IBC: –  §12.9.4.2 -

•  If Vt < 0.85CsW, and •  If Cs is determined (governed) by Eq. 12.8-6

–  Cs = 0.5S1/(R/Ie) (using mapped S1≥0.6g),

•  Then, the drifts shall be multiplied by (0.85CsW)/(Vt) –  Otherwise, drifts need only be scaled per §12.9.2


71

Scaling Modal Response Spectrum Analysis Results •  Scaling of seismic forces and drifts from MRSA

results per 2013 CBC: –  2013 CBC §1616A.1.13 replaces ASCE §12.9.4 with:

•  Modal base shears used to determine forces and drifts shall not be less than those calculated per the equivalent lateral force procedure of §12.8

•  If Vt < 100%V, force results shall be multiplied by: (V)/(Vt)

–  If Tcalc > CuTa, two separate comparisons can be made as it is acceptable to calculate V for drift comparison based on full calculated fundamental period per §12.8.6.2


72



Out-of-plane Effects on Two-Story Wall Panel •  Given the following:

–  Wall dimensions and weight –  Seismic parameters SDS and Ie

–  Flexible roof diaphragm, Lf = 300 ft –  Rigid floor diaphragm

•  Determine the following: –  Out-of-plane forces for:

•  Wall panel design •  Wall anchorage design


73

Out-of-plane Effects on Two-Story Wall Panel •  Out-of-plane forces for wall panel design

–  Fp = 0.40SDSIeww ≥ 0.1ww (§12.11.1) •  Force does not vary with height of wall •  Depending on SDS, Ie, and ww, wind forces may govern •  Parapet forces shall be determined per §13.3.1 (see DE 41)


74



Out-of-plane Effects on Two-Story Wall Panel •  Out-of-plane forces for wall anchorage design

–  Fp = 0.4SDSkaIeWp (Eq. 12.11-1) > 0.2kaIeWp (§12.11.2) •  ka = 1.0 + (Lf / 100) ≤ 2.0

–  At flexible roof diaphragm with Lf = 300ft, –  ka = 1.0 + (300 / 100) = 4.0 ≤ 2.0

•  Fp = 0.8SDSIeWp > 0.4IeWp

–  At rigid floor diaphragm with Lf = 0 (by definition), –  ka = 1.0

•  Fp = 0.4SDSIeWp > 0.2IeWp

–  If all diaphragms are not flexible, then Fp could be modified by (1 + 2z/h)/3 per §12.11.2


75

QUESTIONS?



77

The 2012 IBC SEAOC SSDM Webinar Series

•  Oct 17th Vol. 1: Code Application (ASCE 7) •  Oct 30th Vol. 3: Concrete •  Nov 7th Vol. 2: Wood and Masonry •  Nov 14th Vol. 4: Steel •  Jan 16th Vol. 5: Isolation and Damping

78

Date post:	06-Dec-2015
Category:	Documents
Upload:	bun2it
View:	70 times
Download:	21 times

2013-10-17 Seaoc Ssdm Series Ppt Vol 1 Handout

Documents