Examining progressive collapse robustness of a high-rise reinforced concrete building

To examine high-rise building robustness to sudden column removal, progressive collapse studies of a 13-story flat-slab reinforced concrete (RC) core-wall building system were completed in this study. Two buildings on the University of Nebraska-Lincoln (UNL) campus, Cather and Pound Halls, were demolished in December of 2017. UNL researchers were given unique access to the building sites to assess their response before, during, and after the event. Prior to demolition, accelerometers were placed throughout both buildings, and ambient measurements were conducted to establish natural frequencies and mode shapes. The response of both buildings during controlled demolition was recorded and analyzed using time histories from the accelerometers. Controlled demolition initiated with sequential blast detonation at selected column sections that resulted in progressive collapse. A detailed 3D nonlinear numerical model of Pound Hall was developed using LS-DYNA to mimic the progressive collapse. The accuracy of the building model was evaluated via comparisons between (i) simulated and measured building ambient frequencies and modes; and (ii) displacement and video recorded during the fullscale demolition. The validated model was then used to further investigate damage scenario effects on the robustness of high-rise RC buildings caused by sudden removal of columns at various locations on the ground floor. The study results can be used to develop and calibrate the nonlinear numerical model for analyzing highrise building progressive collapse behavior and can help provide information that may improve new and existing flat-slab RC core-wall building robustness against progressive collapse.