Nonlinear Punching Shear Failure Model for Interior Slab-Column Connections

A model for predicting punching shear failures at interior slab-column connections was developed based on experimental results obtained at various universities. This model has been incorporated into a new RC slab element for the nonlinear analysis program, DRAIN-2DM, along with the desired unloading behavior when a punch occurs. A four-story RC frame office building that experienced punching shear failures during the Northridge earthquake was evaluated using this new model and the occurrence of punching shear failures was successfully postcalculated for the ground motion recorded nearest the structure. The study building was evaluated for three ground motions scaled to the same peak ground acceleration. The building response varied for each record, but in general, it was found that the inclusion of punching shear failures can modify the overall building response in terms of drift, fundamental period, inelastic activity, and base shear distribution. In the case of the study building, the presence of the stiffer moment-resisting perimeter frames helped limit the magnitude of the effect that the punching shear failures had on the overall structural response.