Narrow Results

The base isolated system takes advantage of enhancing the earthquake-proof performance of the structure by means of reductions of input seismic motions. In order to perform reliable evaluation of the response of structures under dynamic loads such as earthquakes, it is necessary to examine their nonlinear response characteristics. In this study, the uncertain parameter effects on the base isolated system related to the nonlinear dynamic response are examined with Monte Carlo Simulation. It is suggested that the uncertain parameters provide significant roles on the maximum responses evaluations of the base-isolated system.

Impact response of structures supported on the sliding systems to real earthquake ground motion is investigated. The base-isolated structure is modeled as shear building and adjacent structure as a spring-dashpot (impact) element. The seismic response is obtained by deriving differential equations of motion of the structure with sliding system and solved using Newmark's step-by-step integration technique in iterations. It is found that performance of sliding systems is hampered with impact. Investigations are carried out to find out the effect of parameters of adjacent structure such as stiffness and gap distance on response of base-isolated structure under consideration. Adversity of impact increases with rising stiffness of adjacent structure and is found quite predominant parameter. Damping in adjacent structure mainly shows influence on bearing displacements which reduce marginally with increased damping. Impact response is obtained under varied flexibility of building for different sliding systems to study the performance during impact. It is observed that with increased flexibility, the superstructure acceleration increases. Also, the superstructure accelerations increase with increments in gap distance up to a certain value and for further widening in gap distance, declining trend is observed. For the changes in base mass to floor mass ratio the responses shows meager deviation. It is concluded that superstructure accelerations increases due to the occurrence of impact in base-isolated structures, ultimately resulting into reduction in efficiency of sliding isolation systems.