Computer simulation for the seismic behaviour of bridge expansion joints enhanced with SMA: Case study

This paper concerns the study of the expansion joints of Benha Bridge under seismic loads. The seismic behaviour of its bridge expansion joints has been enhanced by shape memory alloy (SMA) dampers as a form of energy-dissipation device. SMA can dissipate a part of the input energy from the earthquake by generating a counterforce for the induced seismic force, allowing the opportunity to control the joint width and overcome pounding and unseating problems. In this research, MATLAB programs are developed to calculate the joint width responses in the two cases of without SMA and with SMA control devices embedded between adjacent bridge frames, which are modeled as a single degree of freedom system for each frame. Benha Bridge is the subject of this case study, which aims to check and validate the SMA parameter values that their charts have introduced from earlier research and to improve the seismic behaviour of bridge expansion joints by eliminating unseating and pounding problems. The results show that SMA dampers are able to control the joint width and absorb the excess forces caused by nearby expansion joint overlap. Furthermore, SMA design charts are applicable for bridges of multiple frames when they are homogenous in time periods.