Seismic Analysis of a Low-Rise Base-Isolated Structural System

Abstract

ABSTRACT:A base-isolation system was developed for earthquake protection of low-rise structures. The system incorporates spherical supports for the base, a specially designed spring-cam system to keep the base supported under normal conditions, and moves for the duration of the earthquake under the constraint of a spring with optimized stiffness characteristics. The dynamic behaviour of a three-story concrete structure with and without the base isolation subjected to the Taft and El Centro earthquake loads was investigated. The results indicated that the absolute peak acceleration and displacement as well as shear forces decreased significantly with the application of a base isolation system, and it is possible to achieve 87 to 94% reduction in the maximum accelerations and transmitted forces. The movement of the base relative to the ground was less than 0.15 m in the optimized system, and the springs were not fully compressed at any time during application of the earthquake loads. The maximum induced vertical forces as a result of the spherical base support were found to be less than 1.5 % of the weight of the structure. Since the system performance is highly dependent on the rapid unlocking of the cams in the event of a seismic disturbance, careful consideration should be given to the optimal design of the spring-cam system.

Passive vibration control in a civil structure: Experimental results

“…. ) is equal to the stiffness matrix Ky(t) achieved in Equations (1) and (4). The application of a TMD increases the energy dissipative and the absolute kinetic energy and elastic stored energy decrease from an input energy provided by an external force € z(t) and consequently the structural response is reduced.…”

“…In general, the design and construction of hazard-resistant structures like buildings and skyscrapers are necessary in modern cities. [1][2][3] These designs implement schemes of structural control very useful for real applications with the intention to reducing the negative effects such as the risk of crack or collapse caused by an earthquake. These schemes are known as passive, semi-active and active vibration control in civil engineering.…”

Low Frequency Experimental Analysis of Dry Friction Damping in Cable Isolators

“…When vibrations are of high amplitude and short duration they are regarded as impacts, and the isolator requires storing and dissipating a large amount of energy in short times. A common example of high level vibration is earthquake excitation where normally base isolation techniques are applied [1]. High level excitations are also common in vehicles, where passengers and drivers should be protected from this vibrations, here suspensions for seats are used, especially for large trucks [2,3].…”