Fragility curves for seismic assessment of reinforced concrete buildings with shape memory alloy in regular, torsional irregularity and extreme torsional irregularity

The design and construction of irregular buildings has always been the focus of attention due to the demand for a beautiful and unique structure. Furthermore, the use of Shape Memory Alloys (SMAs) has expanded due to the improvement of the behavior of RC structures in the last decade. The main advantages of using this alloy are its super-elasticity and the reversibility of inelastic displacements of the structure. In this paper, the behavior of reinforced concrete structures with SMA alloy in regular, torsional irregularity and extreme torsional irregularity are investigated. The effect of using this alloy has been shown using fragility curves in different degrees of irregularities than conventional concrete structures. In this regard, the effects of memory-shaped alloys as longitudinal reinforcement in short-order, intermediate, and high-order structures with three different arrangements of longitudinal reinforcements have been investigated. Different types of reinforcement arrangements are the case of full Steel, the case of SMA at the plastic region of the beams and steel reinforcement in other regions and finally the case of SMA reinforcement over the entire length of the beams.Then, several increasing nonlinear dynamic analysis (IDA) were performed under the influence of the 10 selected accelerometers, and maximum drift of each analysis was obtained and the fragility curves were calculated in accordance with the HAZUS instruction for each structural case. The results indicate that the presence of memory alloy in irregular buildings will reduce the damaging effects of irregularities, including maximum drift and residual drift of the structure. This result suggests that the use of SMA alloy in torsional irregular and extreme torsional irregular buildings can reduce the structural damage caused by a possible severe earthquake.