Experimental behavior of elastomeric bearings and seismic bars of simply supported Chilean bridges

Abstract

Typical highway bridges in Chile consist on two span simply supported structures with prestressed concrete girders connected by a continuous slab. The girders are supported by elastomeric bearings which are not bolted and allow sliding of the superstructure. In some bridges, the lateral displacement of the superstructure is also restricted by lateral reinforced concrete or steel stoppers. According to the Chilean seismic design code, the bridges are designed with seismic bars, which are vertical steel rods that connect the superstructure with the bearing table and are intended to prevent the uplift of the superstructure. However, when bridges are subjected to large lateral displacements the seismic bars provide lateral restrain. The objective of this paper is to summarize the experimental campaigns of elastomeric bearings and seismic bars that were conducted at Pontificia Universidad Católica de Chile to characterize the seismic behavior of Chilean bridges. For the elastomeric bearings campaign, six bearings were tested under monotonic and cyclic loads. For the seismic bars campaign, five specimens were tested to quantify the lateral restrain that the seismic bars provide to the bridge superstructure. Two specimens represented the seismic bars of bridges with reinforced concrete diaphragm and three specimens represented those of bridges without diaphragm. From the conducted tests, the force deformation relationship of elastomeric bearings and seismic bars were obtained. Additionally, the behavior and failure mode of these elements were characterized.