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Seismic Testing of an Isolated Scale-Model Bridge Structure with an Adaptive Passive Negative Stiffness Device N. Attary and M.D. Symans Rensselaer Polytechnic.

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Presentation on theme: "Seismic Testing of an Isolated Scale-Model Bridge Structure with an Adaptive Passive Negative Stiffness Device N. Attary and M.D. Symans Rensselaer Polytechnic."— Presentation transcript:

1 Seismic Testing of an Isolated Scale-Model Bridge Structure with an Adaptive Passive Negative Stiffness Device N. Attary and M.D. Symans Rensselaer Polytechnic Institute S. Nagarajaiah and D.T.R. Pasala Rice University A.M. Reinhorn, M.C. Constantinou, and A.A. Sarlis University at Buffalo D. Taylor Taylor Devices, Inc Quake Summit, Boston, MA Session 4, Base Isolation/Energy Dissipation July 11, 2012

2 NEESR-SG: Development of Next Generation Adaptive Seismic Protection Systems Satish Nagarajaiah Professor Civil & Mechanical Eng. Rice University Michael Symans Associate Professor Civil Engineering Rensselaer Polytechnic Institute Andrei Reinhorn Professor Civil Engineering University at Buffalo Michael Constantinou Professor Civil Engineering University at Buffalo Jian Zhang Assistant Professor Civil Engineering Univ. of Calif. Los Angeles Douglas Taylor President, Taylor Devices, Inc. Mechanical Engineering Taylor Device Inc. 2 Research supported by National Science Foundation CMMI Grant No (NEESR - Network for Earthquake Engineering Simulation Research) Project Team

3 Outline Seismic Protection Systems for Bridges Concept of Negative Stiffness Development of Mechanical Negative Stiffness Device Implementation of Negative Stiffness Device within a Quarter-Scale Bridge Structure 3

4 Advanced Seismic Protection Systems for Bridges 4 Patten (1998) Semi-active control using variable-orifice fluid damping/stiffness device (implemented in highway bridge in Oklahoma for vibration control) Sahasrabudhe and Nagarajaiah (2005) Semi-active control of isolated bridge using: – Magnetorheological (MR) dampers – Variable stiffness devices Small-scale bridge model

5 Improved Seismic Performance via Combined Weakening and Damping 5 Source: Reinhorn et. al. (2002)

6 Concept of Negative Stiffness Force develops in same direction as imposed force 6 Positive vs. Negative Stiffness Adding Positive/Negative Stiffness to a Basic System with Positive Stiffness

7 Working Principle of Negative Stiffness and Positive Damping in Structures 7 Source: Nagarajaiah et. al. (2010)

8 Pseudo-Negative Stiffness in Bridges Source: Iemura and Pradono (2003) 8 Cyclic Testing of PNS Damper With PNS, Both Force and Displ. Reduced

9 True Negative Stiffness Device 9 Deformed Shape Undeformed Shape - Device is completely passive (no external power source needed) - Device has adaptive behavior (stiffness varies with displacement in a controllable manner) Passive Adaptive NSD

10 Analytical Force- Displacement Relation of NSD 10 Distance from spring pin to hinge pinL 1 = 10 in Distance from lever pin to hinge pinL 2 = 5 in Vertical length of main springL p = 30 in Stiffness of main springK s = 0.8 kips/in Pre-load of main springP in = 4.4 kips F g = Force in gap-spring assembly Values of Parameters for Bridge Model Analysis Neglecting inertial effects, friction at pins, and flexibility of steel framing members: v AB v BC v CD lsls l1l1 l2l2 u U( ) l1l1 l2l2 F Bh F NSD FSFS FSFS A B C D FgFg F Bv F Dv

11 Force-Displacement Relation in Gap-Spring Assembly 11 Disp. Force d gap P comp K stiff K stiff K soft K stiff +K soft P comp K Soft K Stiff

12 12 NSD Force-Displacement Relation Source: Sarlis, Pasala, Constantinou, Reinhorn, Nagarajaiah, and Taylor (2011)

13 Implementing NSD's in Bridge Model 13 Quarter-scale single-span highway bridge with clear span of 4.8 m and deck weight of 35.5 kips NSD's located under bridge deck within isolation system Isolation system: – Elastomeric bearings (low damping) – Elastomeric bearings + fluid viscous dampers – Elastomeric bearings + NSD's – Elastomeric bearings + fluid viscous dampers + NSD's

14 Component- and System-Level Analytical Force-Displacement Relations 14 Bearings Bridge with Bearings + NSD's Bearings + NSD's NSD's

15 Cyclic Testing of NSDs 15 Harmonic Test Amplitude = 3" Freq. = 0.01 Hz

16 Shake Table Testing of Bridge Model with NSDs Installed 16 SolidWorks Model SAP2000 Model

17 Building and Preparing Bridge Model 17 New Bridge Deck Torsional Restraint and NSD Force Transfer Column Existing Bridge Pier

18 Building and Preparing Bridge Model (Cont.) 18

19 Quarter-Scale Bridge Model on Shake Table at NEES-UB 19

20 20

21 Sine Sweep Test of Bridge Model with NSDs 21

22 Seismic Test of Bridge Model with NSDs: Kobe Earthquake (KJM000 – 100%) 22

23 Summary 23 Conceptual Development – Concept of weakening and damping (via negative stiffness and positive damping) offers potential for improved seismic performance by reducing both forces and displacements. Validation of Analytical Model via Cyclic Testing – Mechanical negative stiffness device (NSD) has been developed and cyclic tests have been performed. Simplified analytical model captures cyclic response. Shake Table Testing of Bridge Model – Negative stiffness device has been implemented in a scale-model bridge structure. Numerical simulations demonstrate potential for improved seismic performance. Shake table testing is underway.

24 Acknowledgments National Science Foundation (NSF) under Grant No. CMMI Mr. John Metzger (Engineering Manager), Taylor Devices, Inc. Mr. Peter Fasolino, K&E Fabricating Co. Staff of NEES & SEESL Laboratories at University at Buffalo (listed alphabetically) – Thomas Albrechcinski (Site Operations Manager) – Myrto Anagnostopoulou, M.Sc. (Structural and Test Engineer) – Christopher Budden (Electronic/Instrumentation Specialist) – Jeffrey Cizdziel (Mechanical Technician) – Goran Josipovic (IT Service Manager) – Duane Kozlowski (Lead Mechanical Technician) – Lou Moretta (Mechanical Technician) – Mark Pitman (Technical Services Manager) – Robert Staniszewski (Mechanical Technician) – Scot Weinreber (Electronic/Instrumentation Engineer) – Shomari White (IT Specialist) 24


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