Restoring-force model for HFC-filled CFS shear walls subjected to in-plane cyclic loading

High-strength foamed concrete (HFC)-filled cold-formed thin-walled steel (CFS) shear wall, as a new-type CFS shear wall, is the major lateral load-resisting member for multi-storey CFS structures. A cyclic restoring-force model has been used extensively in seismic analysis of these shear walls. Experimental study is conducted to investigate the characteristics of hysteretic and skeleton curves, and analyzed the effect of parameter variation on the characteristics. Results indicate that the skeleton curves displayed obvious non-linear characteristics, and the hysteresis loops exhibited significant stiffness and strength deterioration with slipping and pinching effect. By analyzing the typical test skeleton curve and hysteresis loop, seven feature points were defined to represent the hysteretic curve characteristic. A multi-linear restoring-force model was developed to simulate the hysteretic curves and implement in MATLAB software. Eleven representative hysteretic curves obtained from experimental data and the literatures were compared with that of the developed model. The calculated skeleton curves and hysteresis loops agreed with the test results in terms of the evaluation of the feature points and accumulated energy dissipation.