科研之友
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摘要
This article presents a nonlinear static pushdown analysis to evaluate the progressive collapse-resisting capacity curves of typical reinforced concrete frames under different deformations. Unlike the previous studies in which only a few typical columns, such as a column on the bottom storey, are removed, this study examines the column removal scenarios for various typical locations from different stories. The primary findings are as follows: (1) the Vierendeel action causes different internal forces in the beams of different stories, which reduces the progressive collapse resistance under the beam mechanism and delays the development of the catenary mechanism. This may result in the beams failing successively from one floor to another in a frame system, which differs from the theoretical assumption that the beams are damaged simultaneously on different floors; (2) seismic designs significantly improve the progressive collapse resistance under the beam mechanism, especially for lower stories. However such an improvement is less significant for the catenary mechanism and little improvement is found for the top regions of the frame structures. Furthermore, a nonlinear dynamic analysis is conducted to validate the predicted resistances of the reinforced concrete frames in satisfying the requirement of collapse prevention. The design parameters as specified in the existing codes are also discussed.
