This paper provides a broad overview and a guide to implementation with specific case studies being provided from four of more than 240 major buildings and bridges equipped with fluid dampers by Taylor Devices, Inc.
This paper presents an earthquake design procedure and a case study of the Vacaville Police Headquarters. The design goal for this essential facility was to provide immediate occupancy after a 475-year return seismic event. The project also required construction cost within typical code conforming buildings. A combination of Special Moment Resisting Frames (SMRF) and Fluid Viscous Dampers (FVDs) was used as the lateral force resistance system. This system, as described by Gimmel, Lindorfer, and Miyamoto, (2002) results in cost efficiency and superior seismic performance. The 2000 NEHRP (FEMA, 2000) guideline was used to design the project, since it is considered to be a state-of-art procedure for seismic damping devices. This project was the first structure in the United States to use this advanced procedure.
In many metropolitan areas, mid rise buildings are constructed adjacent to existing buildings, and incorporate concrete shear walls to act as a barrier between the two buildings. The orientation of these shear walls often causes severe torsional response within the building. The addition of a few well placed nonlinear Fluid Viscous Dampers (FVD’s) can significantly decrease the torsional excitation, thereby increasing building performance. This paper describes the retrofit of an 18-story steel frame building that exhibits severe torsional response from the “property line” condition at the lower two stories. FVD’s significantly reduce the displacement and acceleration of the second and third floors of the building, where sensitive telecommunications equipment is being housed. They reduce the demand and drift on the stories above with no additional construction required on these floors. FVD’s offer a very economical and effective means of mitigating undesirable building response due to torsional irregularities. Their use would be effective in the retrofit of many existing buildings with similar “property line” conditions.
The end of the Cold War in 1990 heralded a restructuring period for the American military and defense industry. In the civil engineering field, high capacity fluid dampers have transitioned from defense related structures to commercial applications on buildings and bridges subjected to seismic and/or wind storm inputs. Because fluid damping technology was proven thoroughly reliable and robust through decades of Cold War usage, implementation on commercial structures has taken place very quickly. This paper provides a broad overview as well as a guide to implementation; with specific case studies for four of the more than 300 major buildings and bridges equipped with fluid dampers by Taylor Devices, Inc., a defense contractor from the Cold War years.
Structures with high rigidity experience relatively small deflections and interstructural velocities under seismic shock. This means that conventional energy dissipation devices may not be feasible or cost effective. An improved damper configuration has been investigated, utilizing a toggle mechanism to magnify internal structural deflections. This provides a more effective way to add damping to a stiff structure. Experimental results were obtained from a 32,000 lb. test structure utilizing two fluid dampers and two toggle brace elements. Test inputs included around eighty individual earthquake transients, varying both in wave form and intensity. The results demonstrated the ability of the toggle mechanism to magnify displacements significantly. The toggle brace damping system appears to be an excellent solution to the addition of supplemental damping devices to rigid structures of all types. Advantages include relatively low damper cost, a simple bracing element design, and low installation cost.
This article describes every aspect of the design and construction of the Arrowhead Regional Medical Center, including the use of base isolators and viscous dampers to insure continuous operation even after a major seismic event. The article even includes many of the financial aspects of this huge project.
The Eleven story 450,000 ft2 pyramid shaped office building described in this article was one of the first new buildings in the United States to use Seismic Dampers. This National Headquarters for a financial institution is located in West Sacramento, CA. The basic lateral force resisting system of the building consists of steel moment frames. In addition, approximately 15% of critical damping was provided using Fluid Viscous Dampers (FVD) in order to reduce displacement and acceleration. The steel moment frames were designed to remain well below the yield strength, and the story drift ratio was limited to 0.005 to protect the welded moment connections for the Design Basis Earthquake (DBE). Earthquake performance, cost effectiveness, and architectural requirements were the primary concerns in designing this building.
This paper discusses the test methodology and procedures developed for an application within the buildings of a medical center complex in Southern California.
Hotel Woodland is one of the first structures in North America to be seismically retrofitted using viscous dampers. This four story 1927 vintage Historical Landmark reinforced concrete building is located in Woodland, California. It was essential to improve the earthquake response performance of the building and minimize cost while maintaining the historical appearance of the building. This paper presents the processes and decisions regarding retrofit criteria and design procedure for earthquake demand, building response performance, historical interests, and economic considerations.
This paper describes the dynamic testing of a 320 kip viscous damper using both sinusoidal excitation and a drop test machine.