Effectiveness of LRB in Curved Bridge Isolation: A Numerical Study

Abstract

Lead Rubber Bearings (LRBs) represent one of the most widely employed devices for the seismic protection of structures. However, the effectiveness of the same in the case of curved bridges has not been judged well because of the complexity involved in curved bridges, especially in controlling torsional moments. This study investigates the performance of an LRB-isolated horizontally curved continuous bridge under various seismic loadings. The effectiveness of LRBs on the bridge response control was determined by considering various aspects, such as the changes in ground motion characteristics, multidirectional effects, the degree of seismic motion, and the variation of incident angles. Three recorded ground motions were considered in this study, representing historical earthquakes with near-field, far-field, and forward directivity effects. The effectiveness of the bi-directional behavior considering the interaction effect of the bearing and pier was also studied. The finite element method was adopted. A sensitivity study of the bridge response related to the bearing design parameters was carried out for the considered ground motions. The importance of non-linearity and critical design parameters of LRBs were assessed. It was found that LRBs resulted in a significant increase in deck displacement for Turkey ground motion, which might be due to the forward directivity effect. The bi-directional effect is crucial for the curved bridge as it enhances the displacement significantly compared to uni-directional motion.

RBF-Based Integrated Optimization Method of Structural and Turning Parameters for Low-Floor Axle Bridge

“…To reduce the total cost of the blank and the turning process of an axle bridge, a mathematical model for integrated optimization was built with total cost as the objective, and the dimensions and turning process parameters of the axle bridge structure as design variables, as shown in Equation (9).…”

“…In the process of optimization design, conventional methods often necessitate multiple iterations of finite element simulation analysis [8,9]. However, these methods involve high computational costs, which cannot meet the swift and efficient design requirements for engineering products.…”

The Geometric Configuration of Lubricant Recesses of the Polymer Sliding Layer of the Bearing

“…Designs 2023, 7, x FOR PEER REVIEW 3 of 18 different fields for approximately the same type of tasks, namely as a protective and reinforcing coating [38], such as corrosion protection [33], the use of biocompatible polymers as certain grafts [34,35], mouth guards [36], etc. They are used to reduce the size of multifunctional parts and structures [37,39], to reduce friction in bridge bearings [19,41], and in ball or roller bearings [40]. Polymers are used as protective antifrictional layers in bridge bearings.…”

“…At the same time, bridge performance depends largely on the ability of bridge bearings to fulfill their functions and absorb seismic loads. Researchers consider various improvements and modifications of bridge bearings to expand their functionality [9][10][11][17][18][19][20][21].…”

“…In [18], a jack is introduced that can be used for repair works even when seismic vibrations occur, which greatly simplifies works in seismically active zones. In general, there is a large set of work aimed at reducing bridge vibrations, such as the modernization of lead rubber bearings (LRBS) [19] and the study of a combination of different improvements both in the structural elements [20] and in themselves [17]. The Triple Friction Pendulum Bearing (TFPB) with adaptive behavior, which performs a non-linear dynamic analysis of the input data and tunes the system during operation [21], was also introduced.…”