Optimum characteristic properties of isolators with bilinear force–displacement hysteresis for seismic protection of bridges built on various site soils     

Murat Dicleli  Memduh Karalar 《Soil Dynamics and Earthquake Engineering》2011

In this study, closed form equations as functions of the isolator, bridge and ground motion properties are formulated to calculate the optimum characteristic strength, Q_d and post-elastic stiffness, k_d, of the isolator to minimize the maximum isolator displacement (MID) and force (MIF) for seismic isolated bridges (SIBs). For this purpose, first, sensitivity analyses are conducted to identify the bridge, isolator and ground motion parameters that affect the optimum values of Q_d and k_d. Next, for the identified parameters, nonlinear time history analyses of typical SIBs are conducted to determine the optimum values of Q_d and k_d for a wide range of values of the parameters. Next, nonlinear regression analyses of the available data are conducted to obtain closed form equations for the optimum values of Q_d and k_d, to minimize the MID and MIF. The equations are then simplified for various site soil conditions. It is observed that the optimum Q_d and k_d are highly dependent on the site soil condition. Furthermore, the optimum Q_d is found to be a linear function of the peak ground acceleration.  相似文献