Characteristics of lead rubber bearings for elastic response ofbridges substructures

摘要

The main objective of bridge isolation is the protection of the substructure byrnreducing the force demands and improving its energy dissipation capabilities for limiting therndisplacement demands. This paper presents the study of typical reinforced concrete bridges inrnMexico aimed at determining the isolator parameters for obtaining elastic or limited inelasticrnbehavior of the piers. A parametric analysis of the seismic behavior of short and medium spanrnbridges with lead rubber bearings isolators, using the most common structural types built inrnMexico was carried out. The selected model bridges were subjected to time history records ofrnearthquakes with epicenters in the subduction faults in Mexico. The strength and stiffnessrncharacteristics of the substructure and the isolation system were the basic parameters of interestrnin the study. The non-isolated models were designed by using 3D models with the SAP2000rnprogram. Inelastic analyses of the isolated and non-isolated bridge models were achievedrnselecting planar models and subjecting them to time history acceleration records using thernDRAIN2DX program. The range of the isolator parameters values required to maintain the piersrnin the elastic branch of behavior is determined. The results can also be used as a guide for arnpreliminary selection of the best isolator parameters for bridges located in zones affected byrnsubduction fault earthquakes.