Performance of sliding systems under near-fault motions

Response of structures supported on the sliding systems under near-fault ea rthquake ground motion is investigated. The fault normal and parallel compo nents are applied in two horizontal direction of the system. The superstruc ture is considered to be rigid and the frictional forces mobilized at the i nterface of the sliding system are assumed to be velocity dependent. The in teraction between frictional forces of sliding system in two horizontal dir ections is duly considered and coupled differential equations of motion of the system are solved in the incremental form using step-by-step method wit h iterations. The iterations are required due to dependence of the friction al forces on the response of the system. The response of the system is anal yzed to investigate the performance of sliding systems under near-fault mot ion. In addition, the effects of velocity dependence and bi-directional int eraction of frictional forces on the response of isolated system are also i nvestigated. The response of sliding system due to fault normal and paralle l components is found to be more or less uncorrelated and the resultant sli ding base displacement is mainly contributed by the fault normal component. It is also observed that the dependence of friction coefficient on relativ e velocity of system does not have noticeable effects on the peak response of the isolated system. However, if the effects of bi-directional interacti on of frictional forces are neglected then the sliding base displacements u nder near-fault motion will be underestimated which can be crucial from des ign point of view. (C) 2001 Published by Elsevier Science B.V. All rights r eserved.