Mitigating Seismic Bridge Damage through Shape Memory Alloy Enhanced Modular Bridge Expansion Joints

Abstract

Modular bridge expansion joints (MBEJs) are common large capacity bridge joints supplied throughout the United States. Most common are the single support bar service joints, though dedicated seismic variations exist at increased manufacture and installation cost. This paper assesses the effectiveness of a burgeoning subgroup of modular bridge expansion joints comprising of shape memory alloy (SMA) enhanced single support bar variations that maintain service performance and aim to improve seismic joint performance. Such an effective subgroup could potentially increase the inventory of bridges with seismically resistant joints and improve post-event functionality since joint damage often inhibits traffic passage. To this end a set of ten synthetic ground motions are used to simulate the behavior of both an as-built and an SMA enhanced modular bridge expansion joint. A simplified one-degree of freedom bridge-abutment model is used to estimate bridge-joint behavior. The differences between the standard MBEJ and the SMA enhanced MBEJ demonstrate that the addition of shape memory alloy properties improve the joint's ability to accommodate seismic movements.