Effect of lead rubber bearing characteristics on the response of seismic-isolated bridges

Abstract

A parametric study is conducted to investigate the effect of lead rubber bearing (LRB) isolator and ground motion characteristics on the response of seismic isolated bridges. The purpose was to investigate the most favorable parameters of the LRB for minimum earthquake response of the isolated bridge system for different ground motions. The important parameters included are: ground motion characteristic by considering peak ground acceleration to peak ground velocity, PGA/PGV ratio as damage index; characteristic strength, Q d of the LRB isolator normalized by the weight acting on the isolator; flexibility of isolator by varying post yield time period, T d ; and yield stiffness to post yield stiffness, K u /K d ratio. The performance of seismic isolated bridge is measured by the variation of maximum isolator displacement (MID), maximum isolator force (MIF), deck acceleration and pier base shear. For a specified ground motion, smaller MID and MIF are regarded as indicator of better seismic performance. It is found that there exists a particular value of Q d /W, T d and K u /K d for which the MID, MIF, deck acceleration and pier base shear attain the minimum values. Finally the recommendations are made which are useful for the design engineers at the preliminary seismic isolation design of the bridges with LRB isolator for the ground motion having different characteristics.

Influence of ground motion characteristics on the optimal single concave sliding bearing properties for base-isolated structures

“…The results of their extensive parametric study demonstrated that the choice of the seismic ground motion according to the characteristics of the bridge site is crucial for a correct design of the isolators. Similar conclusions in the context of isolated bridges have been drawn by [28]- [29]. A recent work of [30] has evaluated the optimal friction of FP isolators for three different sets of artificial records representative of different soil conditions.…”

“…For this purpose, the nondimensionalization of the governing equations of motions proposed in [20] and [30] for the two-degree-of-freedom (2dof) model describing the problem is extended to include an additional ground motion parameter which is equal to the ratio PGA/PGV between the peak ground acceleration (PGA) and the peak ground velocity (PGV) of the input ground motion. This ratio has been shown in many studies to represent synthetically important ground motion features as frequency content and duration [27]- [36] and it has already been employed in previous works analyzing the relation between the seismic input and the optimal isolator properties [27]- [29]. Two different families of ground motions are considered in this study, representing respectively near-fault and far-field seismic records.…”

Study on the effect of the friction coefficient on the response of structures isolated with friction pendulums

“…A solution to reduce the effect of ground motion is the insertion of elastomeric elements between the soil and the protected structure. These devices, largely presented in the literature are the natural rubber [5][6][7], lead rubber [8] or hybrid lead rubber bearings [9,10]. Models of such devices can be found in [11,12].…”

Damping Properties of Natural rubber/ Epoxidized Natural Rubber composites with different fillers

“…With the development of railway, the demand for rubber shock absorber is becoming larger and larger [3,4] . Moreover, the bridge bearing is also widely used rubber shock absorber [5] . And with the increasing frequency of earthquakes, rubber shock absorber used on building attracts people's attention and becomes processing damping area [6] .…”