Modeling Methods for Collapse Analysis of Reinforced Concrete Frames with Infill Walls

Progressive collapse behavior of RC infilled frames is studied experimentally under quasi-static loading and numerically by using macro (strut) and micro (finite-element) models to simulate the damage propagation within infill walls. A three-strut model is proposed to simulate the overall behavior of infill walls based on the observation that corner regions of infill walls play an important role even after the cracking of the diagonal region in infill walls. The proposed three-strut model is implemented using commercially available software. The accuracy of the proposed method is evaluated by comparing the experimental data with simulated responses from detailed finite-element models and simplified strut models. The modified three-strut model is also compared with other widely used strut models. The comparison shows that the proposed three-strut model predicts the maximum resistance force with higher accuracy. Finally, a simpler model is developed based on the proposed three-strut model for infill walls. This simpler model can easily be implemented by practicing engineers to predict the overall behavior of the infilled frame with acceptable accuracy. (C) 2019 American Society of Civil Engineers.