An analysis of pounding mitigation and stress waves in highway bridges with shape memory alloy pseudo-rubber shock-absorbing devices

Seismic-induced pounding between adjacent structures that are insufficiently separated can cause significant structural damage, even collapse, during severe earthquakes. This paper presents an experimental and numerical investigation into mitigating pounding on highway bridges using novel shape memory alloy pseudo-rubber shock-absorbing devices (SMAPR-SADs). The mechanical properties and a theoretical model of SMAPR-SADs are briefly introduced and investigated. Next, a series of shaking table tests on a 1:30 model of a steel highway bridge are conducted to investigate the effectiveness of the SMAPR-SADs in mitigating the pounding of the structures. Based on the experimental results, the pounding-induced stress waves are analyzed using wave theory and the cross-wavelet transform method. Subsequently, numerical models of highway bridges with and without SMAPR-SADs are proposed. The pounding mitigation mechanism of SMAPR-SADs is analyzed using the momentum theorem, their ability to dissipate energy, and stress wave absorption theory. Two indexes representing the energy absorption and dissipation abilities of SMAPR-SADs are proposed and investigated. Finally, the effect of the axial stiffness of SMAPR-SADs on pounding mitigation is analyzed. The experimental and theoretical results demonstrate that SMAPR-SADs are able to absorb energy stably and can significantly reduce the pounding response of highway bridges under seismic excitations.