Numerical study on reinforced concrete beam-column frames in progressive collapse

Abstract

The objective of current research is to numerically investigate the deformation behaviour of reinforced concrete (RC) beam-column framed structures subjected to destructive external loading. Firstly, besides the conventional uniaxial concrete models to predict flexural failures, a unified plasticity concrete model is proposed to accurately simulate shear deformations of beams. Secondly, a three dimensional co-rotational beam finite element is formulated with considerations of material nonlinearities for both steel and concrete. The proposed co-rotational beam formulation is shown to be capable of predicting steel and reinforced concrete framed structures with satisfactory accuracy and efficiency. Thirdly, a component-based mechanical model is proposed to simplify two dimensional RC beam-column joints, where three types of components are considered, viz., the bond-slip component, shear-panel component and interfacial shear component. Analytical models are respectively proposed to reasonably calibrate the bond-slip component and the shear-panel component, and an empirical model is summarized for the interfacial shear component based on extensive experimental results and design regulations. Fourthly, as an integrated system, the proposed concrete models, the co-rotational beam element and the component-based joint model are studied at the system level to show the prediction accuracy, computational efficiency and robustness in numerical algorithms. Advantages and disadvantages of different concrete models are also discussed. Finally, a superelement concept is proposed for structural analysis of large-scale structures. Compared with models without superelement, significant saving in computational cost and satisfactory prediction accuracy can be obtained without any loss in critical information of structural responses. This aspect is particularly crucial for progressive collapse analysis of structures subjected to localized damage.