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59. TEST REPORT FOR 50 TONNE FORCE VISCOUS DAMPING DEVICES
This test report describes the dynamic testing under sinusoidal excitation of a large viscous damper.
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This test report describes the dynamic testing under sinusoidal excitation of a large viscous damper.
Adding damping by the use of various damping devices has become an accepted method to reduce wind induced vibrations in tall buildings. An interesting example of a 39 story office tower is presented where large projected accelerations are the result of vortex shedding of an adjacent existing 52-story building. Viscous dampers and a toggle brace type motion amplification system are used to suppress the anticipated accelerations. A description of the damping system and its analytical simulation are discussed. This paper includes a nonlinear analysis of the tower, with time history forcing functions derived from wind tunnel testing. Cost data for the damper system is also presented.
This paper evaluates the effectiveness of Fluid Viscous Dampers to reduce blast loading responses in steel buildings. The paper addresses the following issues: (1) development of a blast loading time history from a 3,000 pound explosive charge, (2) characteristics and historical applications of fluid Viscous Dampers for blast and weapon effects, and (3) blast effects and performance comparisons of a conventional steel building frame with and without dampers, and a conventional concrete shear wall building. Simulation results indicate that Fluid Viscous Dampers provide a cost effective way to greatly improve the performance of steel building frames under blast loading.
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.
This article from Bridge Builder magazine shows how Taylor Devices dampers reduce seismic response of bridges.
This report describes a toggle brace damper system that adds significant damping to stiff structures, like reinforced concrete shear wall buildings. It is generally recognized that these stiff structural systems, such as reinforced concrete shear walls and steel braced dual systems, are characterized by small drifts and small relative velocities that make the implementation of seismic energy dissipation devices difficult. This report presents a study on a toggle brace damper system that magnifies the damper displacement and reduces the required damper force to produce the desired damping. The reports presents the concept, describes the theoretical treatment, and includes an experimental study with cyclic and shake table testing of a model structure along with procedures for response history and simplified analysis.
This paper describes shaking table tests of a multi-story scale model building structure subjected to seismic excitation and controlled by a semi active fluid damper control system. The semi active dampers were installed in the lateral bracing of the structure and the mechanical properties of the dampers were modified according to control algorithms which utilized the measured response of the structure. A simplified time delay compensation method was developed to account for delays within the control system. The results of shaking table tests are presented and interpreted and analytical predictions are shown to compare reasonably well with the experimental results. These tests included an undamped system, passive damping, and semi-active damping. Both the purely passive damper system and the semi-active system significantly reduced seismic response.
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.
Base isolation of large structures has proven to be an effective way to attenuate seismic excitation. However it can be costly, and can also involve major building modification. It is now possible to attain a comparable degree of earthquake mitigation with fluid viscous dampers located throughout a structure, without having to isolate the building. This paper describes several techniques for doing this, provides analytical back-up and describes several applications of this technology.