1 / 30

Development of Self-Centering Steel Plate Shear Walls (SC-SPSW)

Development of Self-Centering Steel Plate Shear Walls (SC-SPSW). Jeff Berman Assistant Professor University of Washington. NEESR-SG: Steel Plate Shear Wall Research. Jeff Berman and Laura Lowes. Larry Fahnestock. Michel Bruneau. Graduate Students:

floyd
Download Presentation

Development of Self-Centering Steel Plate Shear Walls (SC-SPSW)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Development of Self-Centering Steel Plate Shear Walls(SC-SPSW) Jeff Berman Assistant Professor University of Washington

  2. NEESR-SG: Steel Plate Shear Wall Research Jeff Berman and Laura Lowes Larry Fahnestock Michel Bruneau Graduate Students: UW: Patricia Clayton, David Webster UIUC: Dan Borello, Alvaro Quinonez UB: Dan Dowden K.C. Tsai Rafael Sabelli Sponsored by NSF through the George E. Brown NEESR Program Material Donations from AISC

  3. Project Overview Resilient SPSW Full-Scale Testing Analysis and Verification of Performance Subassemblage Testing Shake Table Testing Fill Critical Knowledge Gaps a ~43° Cyclic Inelastic Tension Field Action SPSW Damage States and Fragilities Coupled SPSW Testing (MUST-SIM)

  4. Motivation • Current U.S. seismic design codes • Life Safety and Collapse Prevention • Maximum Considered Earthquake (MCE) • U.S. Earthquakes since 19701: • Only 2 people per year die due to structural collapse • $2 billion per year in economic loss Haiti Earthquake (2010) • 1 ATC-69 (2008) US Northridge Earthquake (1994)

  5. Resilient SPSWs: Motivation • Steel Plate Shear Walls (SPSWs): • Thin web plates: tension field action • High initial stiffness • Ductile • Distributed yielding • Replaceable “fuses” (web plates) • However, • Damage in HBEs and VBEs not as easy to repair/replace How can we limit damage to HBEs and VBEs to provide a quicker return to occupancy following an earthquake? (Vian and Bruneau 2005)

  6. Resilient SPSW: SPSW+ PT Frame VPT VSPSW D D Unloading VR-SPSW Plate yields Connection Decompression Plates Unloaded 1st Cycle 2nd Cycle D Connection Recompression Previous PT Connection Work: Garlcok et al. 2002, Christopoulos et al., 2002

  7. SC-SPSW Research Overview Analytical Research Performance-Based Design Procedure Analysis and Verification of Performance System Behavior Experimental Research Subassembly Testing (U. of Washington) Full-scale Testing (NCREE, Taiwan) Shake Table Testing (U. at Buffalo)

  8. R-SPSW Mechanics • Distributed loads on frame from web plates • Compression of HBE from three components: • PT • Web plate loads on VBE • Web plate loads on HBE

  9. Performance-Based Design Collapse Prevention Repair of Plates Only V V2/50 V10/50 First occurrence of: • PT rupture • Excessive PT yielding • Excessive frame yielding • Excessive story drifts No Repair First occurrence of: • PT yielding • Frame yielding • Residual drift > 0.2% V50/50 Plate yielding Connection decompression Vwind D D50/50 D2/50 D10/50

  10. Analytical Model • Nonlinear model in OpenSees • SPSW modeled using strip method: • Tension-only strips with pinched hysteresis • Strips oriented in direction of tension field

  11. Analytical Model (cont.) • PT connection model: Shear transfer Rocking about HBE flanges Compression-only springs at HBE flanges Diagonal springs HBE VBE PT tendons Truss elements with initial stress (Steel02) Rigid offsets Physical Model Analytical Model • Compression-only springs at HBE flanges • Diagonal springs to transfer shear

  12. Dynamic Analyses • 3 and 9 story prototypes based on SAC buildings: 4-6 SPSW bays • Each model subjected to 60 LA SAC ground motions representing 3 seismic hazard levels • 50% in 50 year • 10% in 50 year • 2% in 50 year • Used OpenSeesMP to run ground motions in parallel on TeraGrid machines Processor = 0 Processor = 1 R-SPSW model Processor = n-1 Ranger

  13. Analytical Summary • Results for typical 9-story SC-SPSW • designed WITHOUT optional 50% in 50 year “No repair” performance obj. No Repair Collapse Prevention Repair of Plates Only V • Performance Objectives: • No plate repair (Story drift < 0.5%) in 50/50 • Recentering (Residual Drift < 0.2%) in 10/50 • Story drift < 2.0% in 10/50 (represents DBE) • Limited PT, HBE, and VBE yielding in 2/50 V2/50 V10/50 V50/50 Vwind D All performance objectives met !!! D50/50 D2/50 D10/50

  14. UW Component Tests Reaction Blocks Pin to Allow VBE Rotation Roller to Allow Gap Opening Target Deformation of Specimen Laboratory Configuration Subassemblage

  15. R-SPSW Testing Development of tension field Connection decompression Flag-shaped hysteresis Residual web plate deformation after test

  16. Comparison of Parameters Change in number of PT strands Change in web plate thickness Kr • Affects recompression stiffness, Kr, due to change in PT stiffness • Affects decompression moment • Affects system strength and energy dissipation • Affects post-decompression stiffness

  17. Comparison with Idealized Response • More energy dissipation than assumed • Some “compressive” resistance due to geometric stiffening VSC-SPSW Unloading Plate yields Connection Decompression Plates Unloaded D Connection Recompression 1st Cycle 2nd Cycle

  18. Experimental testing Web Plate Behavior Study FE modeling Pins Residual Load ~25% of yield strength (Webster 2011)

  19. Comparison with Models • OpenSees model • With and without compressive resistance in strips • Future improvements to strip model: • Modify strain hardening rules to account for cyclic yielding • Quantify compression in SPSW strip model

  20. Frame Expansion • As PT connection decompresses, VBEs spread apart Garlock (2002) • Can cause floor damage or increase frame demands if beam growth is restrained, especially at 1st floor beam Kim and Christopoulos (2008)

  21. Accommodation of Frame Expansion • Flexible collector beams connecting PT frame and composite slab • Applies additional point loads along beam • Damage to collector beams Garlock (2007) • Sliding interface between slab and beams • Eliminates slab restraint Kim and Christopoulos (2008)

  22. Elimination of Frame Expansion • Rocking about HBE centerline (Pin) • NewZ-BREAKSS • Rocking about top flange only

  23. Testing at NEES@Buffalo • Quasi-Static tests • 1/3 scale, 3-story • Various PT connection details • Full plate and Strips

  24. Comparison of Behavior • Flange rocking provides better re-centering because of decompression moment • NewZ-BREAKSS prevents floor damage due to frame expansion.

  25. UB Shake Table Tests • 6 degree-of-freedom shake table • Same specimens as quasi-static tests • Scheduled for completion in fall 2012

  26. System-level Testing • National Center for Earthquake Engineering (NCREE) in Taiwan • 2-story, full scale SC-SPSW • Single actuator • Quasi-static loading • Summer 2012

  27. NCREE Specimens • PT column base • Column can rock about its flanges

  28. NCREE Specimens • PT column base • Column can rock about its flanges • 2 specimens • Flange rocking HBEs • NewZ-BREAKSS Connection (Top flange rocking HBEs)

  29. Conclusions • Performance-based design procedure developed for SC-SPSW: • Elastic behavior during frequent events • Web plate yielding and recentering during DBE events • Collapse prevention during MCE events • Analytical studies show SC-SPSWs are capable of meeting proposed performance objectives • Experimental subassembly tests show ‘simple’ models are conservative and have room for improvement • Future testing will verify performance on system level

  30. Thank You Questions?

More Related