Director, Satish Jain & Co Structural Engineers Mumbai, INDIA. Principal, Rutherford & Chekene Consulting Engineers.

Transcription

1 Performance-based seismic design Satish Jain Director, Satish Jain & Co Structural Engineers Mumbai, INDIA Joe Maffei Principal, Rutherford & Chekene Consulting Engineers San Francisco, USA

2 Outline Performance-based design Levels of earthquake and response-history analysis Desired seismic behavior and capacity design Lessons from laboratory research Seismic i Peer Review Conclusions

3 Mumbai s Changing Skyline

4 Issues High real estate prices demand Lean and Efficient ient Structural t Systems Need for efficient, economical and Safe Earthquake Design Need to Go Beyond the Code. What Performance levels l are Acceptable or Required?

5 Seismic Performance Levels 5

6 EQ LEVELS 50% in 50 years 20% in 50 years 10% in 50 years 2% in 50 years Target Performance Levels OP IO LS CP A B C D E F G H I J K L M N O P

7 Two-Stage Design Process Step 1: Design using elastic analysis based on code requirements Step 2: Check design and component behaviour based on non-linear dynamic time-history analysis Ac Ac/g T DESIGN SPECTRUM El Centro Ground Motion Time (Sec) 7

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9 Desired seismic behavior

10 Washington Mutual / Seattle Art Museum Magnusson Klemencic Associates, Structural Engineer of Record NBBJ and Allied Works, Architects

11 Concrete wall shake-table test 7St Story full-scale l building slice Reinforced concrete structural wall University of California, lf San Diego

12 UCSD Wall 3.7 m t w = 200 mm RUTHERFORD & CHEKENE t w = 900 mm Typical High-Rise Core Wall 10 m 18 m

13 EQ4: Test EQ4 PGA = 0.93g

14 EQ4:

15 Flexure-governed wall

16 Prevent yielding outside of intended hinge location

17 Shear failure in diagonal tension

18 Protect against shear failure

19 Weaker wall pier, preemptive diagonal tension

20 Shear Failures In multi-story buildings, shear failures are story mechanisms. Inelastic deformation concentrates t over a limited it height. RUTHERFORD & CHEKENE

21 Flexure-governed versus shear-governed response

22 Prevent Sliding Shear Failure

23 Column shear failure

24 Capacity design

25 Cantilever wall Capacity Design: Engineer designs how and where nonlinear response will occur. Plastic hinge location RUTHERFORD & CHEKENE

26 Coupled wall Plastic hinge locations RUTHERFORD & CHEKENE

27 Dual system, walls plus frames Desired Undesirable mechanism mechanism RUTHERFORD & CHEKENE

28 Reliance on research

29 UCSD Wall Elastic ETABS Model RUTHERFORD & CHEKENE

30 ETABS RESULTS vs. EXPERIMENTAL Roo of Displac cement [i in] 8 EQ3 Wall: E eff = 0.8E c Slab: E eff =05E 0.5E c RUTHERFORD & CHEKENE Time [s] UCSD Test ETABS

31 Roof Dis splaceme ent [in] 8 EQ3 Wall: E eff = 0.2E c Slab: E eff = 0.1E c UCSD Test ETABS Time [s] RUTHERFORD & CHEKENE

32 Test on Japan s E-Defense earthquake simulator

33 Steel Moment Frame Test in Japan p

34 SEAONC- recommended Administrative Bulletin on nonprescriptive seismic design of high-rise buildings Recipient of 2008 Award of Excellence from Structural Engineers of California

35 Seismic Peer Review

36 Peer Review Structural Plan Review Ideally starts at Review of completed schematic design documents Reviews design concepts, methods, and assumptions Typically covers only seismic design RUTHERFORD & CHEKENE Review is for code compliance Covers gravity, wind, seismic, and any other loads

37 Peer Review e Structural Plan Review Peer reviewer gives Authority to professional opinion accept or reject to building authority design Pass-through cost to owner RUTHERFORD & CHEKENE Paid for by permit fees

38 Olivian building, Seattle

39 350 Comparison of 300 SAP model by KPFF vs Perform 150 model by R&C Disp lacement [in] Buildin ng Height [ft] 100 R&C_MAX_X R&C_MAX_Y EOR_MAX_X EOR_MAX_Y % 0.20% 0.40% 0.60% 0.80% 1.00% 1.20% 1.40% 1.60% 1.80% 2.00% Inter-Story Drift Ratio [%] EOR - node X 50 R&C Verification - X RUTHERFORD & CHEKENE

40 Conclusions Design must be based on sound research and principles and substantiated to the building authority of expert reviewers. Performance-based based seismic design can lead to better performance AND a more economical building.

41 References FEMA 306 and 307 Paulay and Priestley 1992

42 References 1999 SEAOC Blue Book SEAOC Seismic Design Manual, Volume 3

43 References > What we do > R&D at R&C > selected publications RUTHERFORD & CHEKENE