1. Seismic Design Methodology for Precast Concrete Floor Diaphragms Research to Practice Webinar April 23, 2012 Sponsored by the Earthquake Engineering Research Institute (EERI) and the Network for Earthquake Engineering Simulation (NEES) Dr. Ned M. Cleland, P.EDr. Robert B. Fleischman Dr. S.K. Ghosh, P.E. Blue Ridge Design, Inc University of Arizona SKG Associates

2. PCI/NSF/CPF PART 1: 2 of 34 NEES/EERI Webinar April 23 2012 Outline Introduce PCI/NSF/CPF DSDM Research Effort Review Key Behaviors of Precast Diaphragms and Design Philosophy Adopted Summarize DSDM Research Project Findings Present Precast Diaphragm Design Procedure Cover Precast Diaphragm Design Example Discuss Codification Efforts

3. PCI/NSF/CPF PART 1: 3 of 34 NEES/EERI Webinar April 23 2012 Outline Introduce PCI/NSF/CPF DSDM Research Effort Review Key Behaviors of Precast Diaphragms and Design Philosophy Adopted Summarize DSDM Research Project Findings Present Precast Diaphragm Design Procedure Cover Precast Diaphragm Design Example Discuss Codification Efforts

4. PCI/NSF/CPF PART 1: 4 of 34 NEES/EERI Webinar April 23 2012 Diaphragm Action Diaphragm action is intended to carry seismic forces horizontally in the floor slab to walls and frames…

5. PCI/NSF/CPF PART 1: 5 of 34 NEES/EERI Webinar April 23 2012 Precast floors can be vulnerable due to the need to transfer forces at discrete locations across floor joints between precast panels Precast Diaphragm Details

6. PCI/NSF/CPF PART 1: 6 of 34 NEES/EERI Webinar April 23 2012 Precast Diaphragm Past Performance

7. PCI/NSF/CPF PART 1: 7 of 34 NEES/EERI Webinar April 23 2012 DSDM Project Objective: Develop an industry endorsed seismic design methodology for precast concrete diaphragms. Scope: Untopped and topped composite precast floor diaphragms. Project Co-funders: CPF, PCI and NSF

8. PCI/NSF/CPF PART 1: 8 of 34 NEES/EERI Webinar April 23 2012 DSDM Consortium Producer Members University of California San Diego Jose’ Restrepo, PI Producer Members Lehigh University Clay Naito, PI Richard Sause, Co-PI Industry Advisory Panel Industry Liaison S. K. Ghosh, Co-PI University of Arizona Robert Fleischman Consortium Leader DSDM Task Group

9. PCI/NSF/CPF PART 1: 9 of 34 NEES/EERI Webinar April 23 2012 DSDM Task Group S.K.Ghosh DSDM Task Group Chair President, S. K. Ghosh Associates R. Becker Vice President Spancrete Industries, Inc. N. Cleland President Blue Ridge Design, Inc. Tom D’Arcy President Consulting Engineers Group N. Hawkins Professor Emeritus Univ. of Illinois Paul Johal Research Director PCI Joe Maffei Engineering Consultant Rutherford & Chekene Engineers Susie Nakaki President The Nakaki Bashaw Group, Inc. Doug Sutton Professor Purdue University Harry Gleich Vice President Metromont Prestress Dave Dieter Vice-President MidState Precasters Industry Task Group Chuck Magnesio Vice-President JVI, Inc Dichuan Zhang, Ge Wan, Michael Mielke, Alicia Mullenbach, Univ. of Arizona Liling Cao, Rui Ren, Wesley Peter, Lehigh Univ. Matt Schoettler and Andrea Belleri, UCSD Graduate Researchers

10. PCI/NSF/CPF PART 1: 10 of 34 NEES/EERI Webinar April 23 2012 Outline Introduce PCI/NSF/CPF DSDM Research Effort Review Key Behaviors of Precast Diaphragms and Design Philosophy Adopted Summarize DSDM Research Project Findings Present Precast Diaphragm Design Procedure Cover Precast Diaphragm Design Example Discuss Codification Efforts

11. PCI/NSF/CPF PART 1: 11 of 34 NEES/EERI Webinar April 23 2012 An aspect of diaphragm behavior not elucidated in the codes is the relationship of the design forces used in equivalent lateral force (ELF) procedures to the inertial forces that may actually develop in floors during a seismic event. Diaphragm Forces Fleischman and Farrow, Eq. Eng & Struc. Dyn, 2001 Diaphragm peak inertial forces may significantly exceed current design values

12. PCI/NSF/CPF PART 1: 12 of 34 NEES/EERI Webinar April 23 2012 The presence of large inertial forces can be critical in precast floor systems: Current Design Code  In combination with complex load paths in floor systems, can lead to inelastic diaphragm action.  Inelastic deformation demands in precast diaphragms will tend to concentrate in the joints between precast units, and only at certain joints.  These demands can exceed the deformation capacity of reinforcing details developed without this consideration, leading to a nonductile diaphragm failure.  High diaphragm flexibility due to the inherently less stiff jointed system, in long floor spans where precast is used effectively, could lead to excessive drift of gravity system columns

13. PCI/NSF/CPF PART 1: 13 of 34 NEES/EERI Webinar April 23 2012  e F px Elastic Design Option (EDO) Maximum Force Demand Diaphragm force Diaphragm lateral displacement Current design force F px Possible Nonductile Response (MCE) Amplified design force Diaphragm Design Approach

14. PCI/NSF/CPF PART 1: 14 of 34 NEES/EERI Webinar April 23 2012 DBE force demand  D F px Elastic design option Diaphragm force Diaphragm lateral displacement Current design F px MCE ductility demand DSDM Design Philosophy Basic Design Option (BDO) Amplified design force force Capacity Design Shear Failure Chord Failure  v  D F px

15. PCI/NSF/CPF PART 1: 15 of 34 NEES/EERI Webinar April 23 2012 Elastic design option Diaphragm force Diaphragm lateral displacement Current design force F px  r F px DSDM Design Philosophy Reduced Design Option (RDO) Yields in DBE Within allowable deformation limits in MCE

16. PCI/NSF/CPF PART 1: 16 of 34 NEES/EERI Webinar April 23 2012 EDO Diaphragm force Diaphragm lateral displacement Current design force F px RDO LDE MDEHDE Connector Classification BDO DSDM Design Philosophy

17. PCI/NSF/CPF PART 1: 17 of 34 NEES/EERI Webinar April 23 2012 Outline Introduce PCI/NSF/CPF DSDM Research Effort Review Key Behaviors of Precast Diaphragms and Design Philosophy Adopted Summarize DSDM Research Project Findings Present Precast Diaphragm Design Procedure Cover Precast Diaphragm Design Example Discuss Codification Efforts

18. PCI/NSF/CPF PART 1: 18 of 34 NEES/EERI Webinar April 23 2012 DSDM Research Flow Diaphragm Level (UA)  Capacity Design Factors.  Internal Force Paths Structure Level (UCSD)  Diaphragm seismic force  Diaphragm flexibility limits FE Pushover Analysis 3D FE Dynamic Analysis MDOF Dynamic Analysis Detail Level (LU)  Characteristics of diaphragm details  Connection classification Full-Scale Detail Tests Scaled Shake Table Test  Hybrid Testing of Joints

19. PCI/NSF/CPF PART 1: 19 of 34 NEES/EERI Webinar April 23 2012 Precast Diaphragm Connector Testing Classify connectors:  Low Defo (LDE)  Mod Defo (MDE)  High Defo (HDE) Connection Details Evaluation Previous Test Results Evaluation Experimental Analytical

20. PCI/NSF/CPF PART 1: 20 of 34 NEES/EERI Webinar April 23 2012 Modeling of Chord Connector  =0.7

21. PCI/NSF/CPF PART 1: 21 of 34 NEES/EERI Webinar April 23 2012 Modeling of JVI Connector Cyclic response

22. PCI/NSF/CPF PART 1: 22 of 34 NEES/EERI Webinar April 23 2012 Modeling of Ductile Mesh

23. PCI/NSF/CPF PART 1: 23 of 34 NEES/EERI Webinar April 23 2012 Discrete FE models Diaphragm Analytical Modelling Nonlinear coupled springs and contact elements

24. PCI/NSF/CPF PART 1: 24 of 34 NEES/EERI Webinar April 23 2012 Prototype Structure #1: Parking Garage

25. PCI/NSF/CPF PART 1: 25 of 34 NEES/EERI Webinar April 23 2012 PDH Test

26. PCI/NSF/CPF PART 1: 26 of 34 NEES/EERI Webinar April 23 2012 PDH Test Results: Flexure CH ServiceCH DBE CH MCE CH Bi-dir DBE BK MCE Joint Flexural Response M  M Weld Fracture Minor Cracking Major Cracking/Crushing

27. PCI/NSF/CPF PART 1: 27 of 34 NEES/EERI Webinar April 23 2012 Shaking Table Structure

28. PCI/NSF/CPF PART 1: 28 of 34 NEES/EERI Webinar April 23 2012 Test Comparison: Knoxville Knoxville DBE δ Diaphragm midspan roof drift

29. PCI/NSF/CPF PART 1: 29 of 34 NEES/EERI Webinar April 23 2012 Phase III: Design Methodology Development

30. PCI/NSF/CPF PART 1: 30 of 34 NEES/EERI Webinar April 23 2012 Modeling of Evaluation Structure Precast units: Plane stress element Chord connector: Nonlinear springs Shear connector: Nonlinear springs Symmetry boundary Column: 3D beam element Spandrel: 2D beam element Connector Elements Moment frame 3D beam element Shear wall 3D shell element

31. PCI/NSF/CPF PART 1: 31 of 34 NEES/EERI Webinar April 23 2012 Suite of Ground Motions SDC E SDC C

32. PCI/NSF/CPF PART 1: 32 of 34 NEES/EERI Webinar April 23 2012 Trial Design Factors Chord connector SDC E AR=3 T, δ T δ Diaphragm Force Amplification Factor 

33. PCI/NSF/CPF PART 1: 33 of 34 NEES/EERI Webinar April 23 2012 Design Methodology Verification: Prototype Structures 4-Story Parking Structure

34. PCI/NSF/CPF PART 1: 34 of 34 NEES/EERI Webinar April 23 2012 Design Methodology Verification: Prototype Structures 8-Story Office Building