NONLINEAR BEHAVIOR OF REINFORCED CONCRETE WALLS WITH SHAPE MEMORY ALLOY REINFORCEMENT SUBJECTED TO EARTHQUAKE

Shape Memory Alloys (SMAs) are new material in structural engineering. They can be used as reinforcement for the concrete walls. In this research, a numerical model was first developed based on an experimental test of a tall reinforced concrete wall with steel reinforcement subjected to an earthquake, and the numerical model responses were compared to the experimental model. Then, three other approaches were examined; first, the shape memory alloys were replaced only as vertical bars on the first story; in the second one, Shape memory alloy bars were replaced only on the first and sixth stories; and in the third approach, the whole vertical bars were replaced with shape memory alloy bars. Nonlinear time history analysis and comparison of model responses were performed. In addition, the parametric study of the responses was also done by changing some model characteristics such as axial force and earthquake intensity. In all three approaches with the shape memory alloy bars, the base moment demand value decreased by approximately 15% compared to the model with steel reinforcement. In the moment demand diagram, the amount of moment demand at the mid-height of the structure is relatively increased compared to the base moment demand. This is due to the effect of higher modes on wall behavior. The moment diagram graph is not uniformly decreasing along the height is not like a straight line. In addition, parametric study of the responses is also performed by changing some model characteristics such as axial force and earthquake intensity. With the formation of a plastic hinge at the base of the wall,approximately, the amount of moment demand in this area remains constant and the effect of higher modes increases the moment demand at the mid-height of the structure and may result in the formation of another plastic hinge at the mid-height of the structure.