PSI - Issue 18

Bilal L. Khan et al. / Procedia Structural Integrity 18 (2019) 108–118 Author name / Structural Int grity Procedia 00 (2019) 000 – 000

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Fig. 3. Time history: Landers Armboy Earthquake PGA 1.46m/sec 2 (Far Field).

4. Results and Discussion

This section presents the results and comparison of dynamic performance of structure. The response of the eight storey structure is investigated under three different bearing pads differentiated on the basis of their effective damping (Low Damping Rubber bearing: LDRB 3% damping, High Damping Rubber bearing: HDRB 13% Damping & Lead Core Rubber Bearing: LCRB 25% damping). Result of parameters like Building displacement, inter-storey drifts, transmissibility of acceleration are compared for isolated building with responses of non-isolated building under near and far field earthquake excitations. Drift is defined as the lateral displacement. Inter-storey drift is the drift of one level of a multi-storey building relative to the level below. The graph in figure 4 represents the inter-storey drift comparison between fixed base structure and base isolated structure with low damping rubber, high damping rubber and lead rubber bearing for near field Lomaprieta Earthquake with a maximum Peak ground acceleration is 4.35 m/sec 2 . It is represented in figure 4 that inter-storey drifts are significantly controlled after applying base isolators of different damping ratio. Till first seven storeys, the difference between performances of these base isolated systems is negligible, however the difference in their performance is observed in the upper most stories where the stiffness of the upper most storey is very less and irregularity in vertical direction of the building is present. High damping rubber bearing (HDRB) has shown the least inter-storey drift and deformations (22 mm) for the Lomaprieta Earthquake, followed by lead rubber bearing and low damping rubber whose inter-story drift ratios are almost the same (52 mm). 4.1. Inter-storey Drift

Fig. 4. Inter-storey Drift Comparison between Base Isolated Structure and Fixed Base Structure for Lomaprieta excitation (Near Field).