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33. Martin Marietta Fluid Viscous Damper Study
This report describes the seismic analysis of a building at Oak Ridge, TN. It shows that the addition of viscous dampers to this structure provides adequate seismic protection.
This report describes the seismic analysis of a building at Oak Ridge, TN. It shows that the addition of viscous dampers to this structure provides adequate seismic protection.
This article summarizes the extensive viscous dampers investigation performed by NCEER at State University of New York, Buffalo Campus. This included computer modeling of both the dampers and complete isolated systems, along with shake table testing and correlation of results. The article also describes a very large damper projects; dampers + base isolation for a set of five hospital buildings near San Bernardino, CA.
This 206 page report presents the results of an extensive study on fluid viscous dampers. A series of component tests with various dynamic inputs was performed to determine the mechanical characteristics and frequency dependencies of the dampers. In addition, temperature dependencies were evaluated by varying the ambient temperature of the damper during component testing. Based on these component tests, a mathematical model was developed to describe the macroscopic behavior of the damper. Earthquake simulation tests were then performed on one story and three story steel structures both with and without dampers. The addition of supplemental dampers significantly reduced the response of the structure for both interstory drift and shear forces. The experimental responses correlated well with analytical predictions.
This paper describes the dynamic testing of a 320 kip viscous damper using both sinusoidal excitation and a drop test machine.
Taylor Devices, Inc. has manufactured damping devices since 1955. Until 1990 most applications were military, using dampers to attenuate weapons effects. Until recently, information on these applications and the associated damper designs has not been public due to security restrictions. Most of these restrictions have now been relaxed and much of this damping technology is now available to the structural engineering community. Taylor Devices can now provide compact fluid viscous dampers in the 100 kip to 2,000 kip output range that greatly reduces earthquake response of structures. This paper describes how the military has been testing shock mitigation dampers for many years and how this type of testing can apply to the large dampers required for seismic protection of structures.
The addition of passive damping to a structure greatly increases its earthquake resistance. It is possible to get further increase through an active or semi-active control system for the dampers. Semi-active damping is preferred due to low external power requirements and fail-safe operation. This paper describes the history of the successful use of semi-active fluidic control devices in military applications and how this technology has been adapted to earthquake hazard mitigation. Testing of a semi-active continuously adjustable damping device through fluid orificing is described. Mathematical models of the behavior of the device are also presented.
This paper presents a review of supplemental damping devices used for the control of the seismic response of structures. The mechanical properties of these devices are discussed and considerations in the design of energy absorbing systems are presented. Conventional structures passively resist earthquakes through a combination of strength, deformability and energy absorption. They have very little damping, so elastic energy absorption is small. Strong earthquakes deform these structures well beyond their elastic limit through localized plastic hinging, which results in increased flexibility and energy dissipation. Most of the earthquake energy is absorbed by the structure through localized damage of the lateral force resisting system. This is somewhat of a paradox in that the effects of earthquakes (i.e. structural damage) are counteracted by allowing structural damage. Structural performance can be greatly improved if a large portion of the input energy can be absorbed, not by the structure itself, but by some type of supplemental device. This paper describes a number of ways to do this, including friction devices, yielding metal systems, elastomeric viscoelastic dampers and fluid viscous dampers.
This specification covers the set of 186 fluid viscous dampers used on the five buildings of the new San Bernardino County Medical Center located in Colton, California. Three major faults are close to this location. The dampers operate in parallel with elastomeric base isolators, and reduce the required isolator stroke from +/- 48 inches to +/- 22 inches. This specification is very detailed and includes testing requirements.
This specification covers the set of ten linear fluid viscous dampers along with their mounting brackets and pins for the Rockwell Building located at Jamboree Road and Birch in Newport Beach, California. These dampers provide an output force in either tension of compression that is directly proportional to the relative velocity between the two ends of the dampers. The damper output force varies only with velocity and does not change with damper stroke position or orientation angle. The function of the dampers is to absorb earthquake energy, thereby reducing the amount the building moves when an earthquake occurs.
This paper describes a large variety of passive energy dissipating devices which can be used within a structural system to absorb seismic energy. These devices can produce significant reductions of inter-story drifts in moment- resisting frames. Furthermore, these devices may under elastic conditions, reduce the design forces.