Influence of the SMA constitutive model on the longitudinal seismic response of RC bridges

Abstract

Several studies indicate that the re-centring capacity presented by superelastic Shape Memory Alloys (SMA) can reduce the displacements of structures subjected to earthquakes. To quantify the errors of numerical predictions with different constitutive models, peak, relative and residual displacements of four two-framed reinforced concrete (RC) bridges, linked by SMA bars, subjected to seismic actions, were numerically assessed. Different ratios of the elastic natural period of vibration of the frames of the bridges were adopted. Lumped plasticity models were used to simulate the behaviour of the reinforced concrete columns. Five SMA uniaxial models were considered, combining linear, nonlinear, isothermal and nonisothermal conditions. The seismic action was modelled by real accelerograms. The results show that the relative displacements are more sensitive to the adopted SMA model than the peak and residual displacements. Significant relative differences, up to 70%, were obtained.