Manufacturing and modeling of SMA composite reinforcement for enhanced performance of concrete structures under sequential ground motion records

Aftershocks are known to cause collapse of structures after acquiring damage from main shock. When strong main shock strikes, reinforced concrete (RC) structures are often vulnerable to impact of aftershocks as they already are weakened due to damage accumulation. This research presents a new type of shape memory alloy (SMA)-based composite reinforcement with ability to withstand seismic forces from main shock and aftershocks while exhibiting pseudo-elastic behavior. In this study, small diameter SMA wires are embedded in thermoset resin matrix with or without additional glass fibers to develop composite reinforcement. These SMA composite specimens are first tested under quasi-static cyclic tensile loading to achieve constitutive material response and then to develop analytical material models. These experimentally calibrated material models are used in structural level models to assess the performance of RC structures under seismic loading. Three storey, one bay prototype RC moment resisting frames (MRFs), reinforced with SMA composite and steel reinforcements, are subjected to sequential ground motions to study their nonlinear behavior and impact of aftershocks. These RC-MRF frames are subjected to incremental dynamic analysis using suite of ground motion records from main shock-aftershock earthquake sequences and a comparison is drawn based on accumulation of damage and residual drifts. It is found that the sequential incremental dynamic analysis technique is a good means to perform post main-shock damage assessment and to evaluate the response of reinforcement structures. Numerical results also show superior performance of SMA composite reinforced MRF in terms of dissipation of energy and accumulation of lower residual drifts.