Utilizing Damping Devices To Improve Resiliency of Structures
Over the last 20 years, utilizing various types of added-damping devices in structures has emerged as a useful, reliable and predictable tool in significantly improving the resiliency of structures to a dynamic input. Much research and testing have been performed that verifies the benefits of incorporating added-damping devices in structures. Linear and non-linear fluid viscous dampers and tuned mass dampers continue to demonstrate excellent performance in reducing deflection, acceleration response, inter-story drift and stress. Damping device designs that have been well proven through decades of use are available in configurations that provide forces that depend on input velocity, deflection, or a combination of both.
Although various building codes have emerged throughout the world that address methods and response requirements of structures when utilizing damping devices, these codes do not provide a general comparison in improved resiliency that is realized through their use.
Presented within this paper is a graphical and visual collection illustrating the benefits of incorporating added-damping devices in structures. Examples include a comparison in terms of absorbed energy, cyclic degradation comparison after a transient excitation and an earthquake level comparison by testing a scaled building model, among others. This collection will provide a strong realization to the reader on how an added-damping device can substantially improve building resiliency to a dynamic transient.
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U.S. Design of Structures with Damping Systems
Many applications of damper devices in both new and existing buildings in both United States and Japan have resulted from extensive damper device development efforts. The increased usage of this technology has created a demand for design guidance and building codes to specify their use in the United States. This paper provides a case study using code type design procedures.
A two-story police head quarters in Vacaville, California with an area of 3,716 m2 (40,000 ft2 ) is summarized. This new building was designed with damping system following the 2000 NEHRP procedures as described in a companion paper.
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Seismic damage control with passive energy devices: A case study
This paper presents a theoretical case study of the effectiveness of supplemental passive damping devices in reducing structural response during seismic excitation. A six-story special moment resistant reinforced concrete frame is studied with and without the aid of supplemental dampers. Response predictions are presented for each case. Physical design requirements are presented for a new facility implementing the supplemental damping system to reduce seismic damage and improve the post-earthquake operational capability of the facility.
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FLUID DAMPERS FOR APPLICATIONS OF SEISMIC ENERGY DISSIPATION AND SEISMIC ISOLATION
Fluid inertial dampers which operate on the principle of fluid flow through orifices have found numerous applications in the shock isolation of military hardware. The adaptation of this hardware and use in civilian applications represents the object of this paper.
The application of these devices as part of seismic energy dissipation systems for buildings and bridges has been experimentally and analytically studied. The study included component testing over a range of temperatures, modeling of devices, shake table testing of 1-story building models, 3-story building models and a bridge model, development of alternate testing methods, analytical prediction of response and development of simplified analysis procedures.
Experimental results demonstrate a significant improvement of the energy dissipation capability of the structures to which the devices are attached. This resulted in substantial drift reductions and under certain conditions in reduction of inertia forces. Within a seismic isolation system, fluid dampers enhanced the system’s ability to dissipate energy resulting in substantial reduction of displacement and almost complete insensitivity of the response to the frequency content of the input. Certain devices with nonlinear viscous characteristics and marked insensitivity to temperature variations have been built and tested for application within seismic isolation systems. One such application involving dampers with strokes plus or minus 600mm and an output force of nearly 1,500 kN will be presented, in addition to two other implementations.
Fluid inertial dampers represent a technology which was developed for military applications and has now been shown to be effective in applications of seismic hazard mitigation, either as elements of seismic isolation systems or as elements of seismic energy dissipating systems. The civil engineering profession has readily accepted this technology, resulting in a number of applications.
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