Comparison of drift and energy depreciation in concrete moment frames using HDRB isolators under near-fault earthquakes
Abstract
Fazel Mirhasani, Mostafa Koohsari Nodeh, Bashir Yazdani
Seismic Isolator Systems in structures can be constructed for buildings with any height according to the Design Regulations available in Seismic Isolator. On the other hand, the behavior of high structures in the past earthquakes indicates the different behavior of these structures in comparison with short buildings. For this purpose, the main objective of this project is to examine the seismic behavior of short, intermediate and high-order concrete moment building without any isolator and comparison them with isolated buildings using High Damping Rubber Bearing (HDRB). Linear and nonlinear structural analysis methods including static linear and nonlinear modal dynamic analysis methods have been used to achieve the results using the Kobe, Morgan Hill, NewZealand, Loma Prieta, Imperial Valley, Northridge, Dinar earthquake records with the help of SAP2000 software. The effect of isolation on structural behavior has been investigated with the definition of 3 frames with fixed base and 3 frames with isolated base as 3-dimensional model for 3 buildings with heights of 4, 8 and 12 storey, and parameters such as amount of relative displacement and energy depreciation are compared with each other. Generally, it was observed that, the amount of energy depreciation is 65.34%, 59.42% and 53% and amount of drift reduction is 58%, 48.71% and 36.48% in structures with seismic isolator in structures 4, 8 and 12 storey than structures with fixed base, on average, under acceleration of reflection maps, respectively, which the energy depreciation of isolators is higher in structures with less storey. This is due to the acceleration response spectrum shape that the rate of acceleration response drop relative to the increase in period, is less amount than that of lower periods in areas with high periods (higher order structures).
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