Collapse analysis of reinforced concrete frames including bar fracture

A nonlinear one-dimensional compound frame element is formulated and applied to collapse analysis of reinforced concrete frames including fracture of longitudinal reinforcing bars. The proposed formulation can take account of geometrical and material nonlinearities including cracking and crushing of the concrete, yielding of steel bars, post-yield tension stiffening and fracture of reinforcing steel bars and fixed-end rotation. The material nonlinearities are formulated within the framework of a distributed nonlinearity model, and the rupture of reinforcing bars is captured by nodal springs with damage multipliers. The developed analytical tool is verified against available experimental data in the literature. It is shown that the developed compound element and proposed modelling strategies can capture the full load-deflection response and the ultimate loading capacity of reinforced concrete beam assemblages/frames subjected to large displacements.