Seismic performances of Mae Lao Bridge with elastomeric bearings and shear dowels

Abstract

The research investigates the behavior of the Mae Lao Bridge, one of the damaged bridges, with elastomeric bearing and shear dowel. The objective of the research is to study the behavior of the bridge under different ground motion including the pier displacement, the girder displacement, the curvature of the column, and the stress-strain curve of the material including the confined, the unconfined concrete, and the reinforcement. Also, the effect of adding the elastomeric bearing and the shear dowel to the bridge is observed. In addition, the difference between the bridge with and without abutment soil spring is compared as well. The whole bridge is modeled using the computational program OpenSees. The bearings are modeled using linear model and the shear dowel as bilinear model; Columns are modeled with three separated parts: the rigid part, the plastic hinge part and the elastic part and so the beams. The analysis is focused on how the different thickness of bearing makes to the bridge structural reaction. The results show that the thicker thickness of bearing can help reduce the displacement of the columns, but increase the displacement on girders. The reduction of displacement on top of pier is about 10% to 25% from 2cm-thick bearing to 8cm-thick bearing of the wall-type piers. The curvature of the section is reduced as well even in some cases that the 8cm-thick bearing keep the section elastic without yielding. On the other hand, the shear dowel reaches its objective as well to help reduce both the displacement on top of pier and the girders if comparing to the case without shear dowels. Although other cases of different thickness of bearing help reduce the displacement and curvature of the column but still the 8cm-thick bearing case gives the best performances overall.