Shock isolation support

Abstract

A seismic isolation bearing comprises a lower plate, an upper plate, and a cylindrical roller in rolling contact with an upwardly facing bearing surface of the lower plate and a downwardly facing surface of the upper plate. The lower plate is fixable to a base, while the upper plate is fixable to a superstructure, for example a bridge deck. One or both bearing surfaces are sloped to form a central trough at which the cylindrical roller resides under normal weight of the superstructure, and toward which the roller is biased when relative displacement between the lower and upper plates occurs to provide a constant restoring force. A pair of sidewall members are fixed to the lower plate to withstand strong forces directed laterally with respect to the isolation axis along which rolling displacement occurs, and a pair of sliding guides carried one at each end of the roller provide dry frictional damping as they engage an inner wall surface of a corresponding sidewall member. The isolation bearing preferably comprises a locking mechanism that prevents relative displacement under normal non-seismic horizontal loading, but allows the bearing to function as intended under seismic loading. Visco-elastic or viscous dampers, linear springs, and nonlinear springs such as hardening springs are preferably mounted between the lower and upper plates to reduce bearing displacement, dissipate energy, and otherwise adjust periodic motion characteristics of the bearing. Further embodiments providing isolation along orthogonal X and Y axes are also disclosed.

Description

technical field [0001] The invention is a kind of shock isolation equipment: during an earthquake, the structure can be protected from the earthquake force, the earthquake damage can be reduced, and the casualties can be reduced. Background technique [0002] One way to improve the seismic response of structures is to use the principle of seismic isolation, so that most of the seismic energy passes through mechanical energy-dissipating devices such as lead blocks-lead cores in rubber bearings, through the friction of sliding bearings, or through additional mechanical energy dissipation. Devices such as steel blocks are dissipative with viscous or viscoelastic damping. In order to prevent the damage of the main structural components, the seismic isolation support system must be able to produce a large horizontal displacement. [0003] The elastic shock-isolation bearing is mainly composed of upper and lower metal plates and an elastic material layer in the middle. The elasti...

AI Technical Summary

Problems solved by technology

Structures with strict space constraints, such as the piers of overpasses, will have a limited width due to the influence of the road, which is a serious disadvantage

Also, the resonant frequency of such bearings may coincide with the frequency of the seismic load, producing excessive displacements

After the earthquake, another shortcoming of this type of support was exposed: the displacement is permanent and irreversible. To return the displaced structure to its original position, a hydraulic jack must be used.

Large displacements occur for two reasons, one is an inherent problem with traditional linear (or slightly nonlinear) bearings: the motion of the superstructure is almost out of phase with ground motion; the other is that many bearing designs do not avoid Large displacement due to instability

Images