Collapse simulation of RC columns under biaxial cyclic loading

Full-blown performance-based seismic design and assessment require multiple nonlinear dynamic analyses of 3D models. Collapse simulation requires the employed response models to be robust up to extreme response levels. For RC columns, the state-of-the-art in the field relies on phenomenological models calibrated versus experiments, whose robustness, computational cost and capability of describing member collapse for use within complex/large building models is unparalleled. These models, however, miss one possibly important aspect: the coupling between the responses in orthogonal planes. This work reports on ongoing research to develop a coupled phenomenological model for RC columns. Preliminary results from a multiple stripe analysis on a test building using an initial, basic implementation of the coupled model highlight a qualitative trend towards higher rates of collapse compared to uncoupled 3D models.