Progressive collapse analysis of concentrically braced frames through EPCA algorithm

This paper introduces a new algorithm, namely the Extended Progressive Collapse Analysis (EPCA) algorithm, whose features, such as potential and capacity of buildings for occurrence of progressive collapse, were investigated. Their failure modes were determined by using pushdown and vertical incremental dynamic analyses. Moreover, by applying this procedure, the element removal impact factor and the most critical locations of such removals were obtained. This algorithm was utilized for progressive collapse analysis of two newly designed concentrically braced frames with different numbers and locations of braced bays in order to quantitatively determine its effect on mitigating progressive collapse. Using this method, the minimum residual capacity and the most critical locations of element loss as well as element removal impact factor for the frames that were studied were determined. Results showed that the frame with two braced bays had more robustness for mitigating progressive collapse, at least to the rate of 17.21% comparing to the frame with three braced bays.

► The EPCA algorithm was developed. ► Pushdown and vertical incremental dynamic analyses were performed. ► Failure modes and failure overload factors were detected. ► Influence of number of braced bays on progressive collapse was determined. ► The dynamic amplification factor of 2.69 for CB-frames was suggested.