Modeling and parameter identification of asymmetric restoring force of reinforced concrete shear walls

Under the action of the seismic waves, reinforced concrete shear walls (RC shear walls) often exhibit hysteresis characteristics such as strength and stiffness degradation, and pinching effects due to factors such as slippage, cumulative damage of concrete, and non-uniform corrosion of steel bars or reinforcements. The hysteresis curve is asymmetric. In this paper, a nonlinear restoring force mechanical model, based on the Bouc-Wen-Baber-Noori (BWBN) model, that can describe the hysteresis characteristics of the RC shear wall is obtained by introducing the asymmetry factor. Particular attention is the solution of equation that the hysteretic energy ε at different loading stages in this model is regarded as parameters to be identified. The ordinary differential equations for parameter identification are derived into four segments. The improved particle swarm organization (IPSO) algorithm is used for parameters identification, which superiority is verified by comparison to the genetic algorithm. The accuracy of this model is verified by using RC shear wall finite element simulation data.