Kurşun çeki̇rdekli̇ kauçuk i̇zolatörlerde deprem etki̇me açisinin maksi̇mum i̇zolatör deplasmanlarina etki̇si̇

Research studies that focused on the response of seismic base isolated structures isolated with lead rubber bearings (LRBs) showed that the performance of isolators are in agreement with the experimental results provided that the actual deteriorating hysteretic behavior of LRBs are used in the analyses. Consequently, deteriorating hysteretic representations for cyclic behavior of LRBs are used in all of the analyses performed in the present study. The objective of this study is to determine the amplification in maximum isolator displacements (MIDs) when LRB isolated structures are subjected to bidirectional excitations of records with different orientations. For this purpose orthogonal horizontal components of ground motions were rotated from their as-recorded original forms by increments of 10o up to 360o and employed in nonlinear response history analyses. In the analyses, first, the original (as-recorded) ground motion is applied to the seismically isolated structure and the corresponding MID is noted. Then, the same structure is subjected to rotated versions of the same ground motion and MID is recorded. To quantify the amplification in isolator displacement due to change in ground motion orientation, MIDs are compared. Once the effect of ground motion orientation is established, a constant that accounts for the amplification in MID due to ground motion orientation is proposed to be used in estimating MIDs by means of original ground motion records. Keywords: Seismic Base Isolation, Lead Rubber Bearings, Maximum Isolator Displacement, Ground Motion Incidence Angle.