DESIGN OF A SEISMIC ISOLATION SYSTEM WITH SUPPLEMENTAL VISCOUS DAMPING FOR A NEAR-FAULTESSENTIAL SERVICES FACILITY
The subject building is the L.A. Regional Transportation Management Center. This steel building encloses five floors comprising about 88,000 square-feet. As an essential service facility it meets the Seismic Performance criteria of Immediate Occupancy after a Maximum Considered Earthquake (MCE). Located within proximity of large active faults (closest at 400 feet), the facility can be subjected to high-velocity pulse-type ground motion. Conventional Base-Isolation utilizing different types of isolators would need to accommodate an impractical 40 of lateral displacement. A supplemental viscous fluid damping (VFD) system was selected combined with Natural Rubber Bearings isolators selected for their reliability, consistency of properties over time, cost effectiveness, wide availability and ease of modeling. Sixteen 320 kip nonlinear VFDs reduce the maximum lateral displacement to 24 without adding elastic stiffness to the system. Due to the low initial stiffness of the isolators and low initial sticking force in the VFDs, an innovative wind-brake ring with adjustable tension bolts was added to the dampers to achieve the required wind load resistance. The considerably lower tension capacity of the isolators compared to compression capacities created challenges when resisting seismic over turning forces. Double end bay spans were created and braced frames utilized as transfer trusses to concentrate dead loads at corners to minimize the upward displacement and isolator tension. A creative modeling technique was devised utilizing a combination of three finite elements, namely; a bilinear biaxial (horizontal) shear hysteretic element with linear axial (vertical) stiffness combined with a uniaxial gap element connected by a rigid link.
Essential Facility Isolation Damping Seismic Steel
Saif Hussain, S.E. Mohamed Al Satari, Ph.D., P.E.
Managing Principal,Coffman Engineers, Inc., 16133 Ventura Blvd., Suite 1010, Encino, California, USA Structural Engineer,Coffman Engineers, Inc., 16133 Ventura Blvd., Suite 1010, Encino, California, US
国际会议
14th World Conference on Earthquake Engineering(第十四届国际地震工程会议)
北京
英文
2008-10-12（万方平台首次上网日期，不代表论文的发表时间）