Progressive collapse resisting mechanisms of reinforced concrete structures

摘要

Reinforced concrete (RC) buildings may be vulnerable to progressive collapse due to lack of\udsufficient continuous reinforcement. Progressive collapse is a situation when local failure is\udfollowed by collapse of adjoining members, which in turn causes global collapse, and can\udeventually result in injuries or loss of life. Design of structures against progressive collapse\udhas not been an integral part of structural design. However, some guidelines such as General\udService Administration (GSA) and Unified Facilities Criteria (UFC) guidelines have detailing\udrequirements to reduce the likelihood of progressive collapse. It is difficult to predict the\udstructural behaviour of building members during progressive collapse because the dynamic\udnature of the event and the limited experimental tests conducted to understand the nature of\udprogressive collapse. Membrane action of beams and floors are important mechanisms of load\udredistribution and progressive collapse resistance in the event of failure of load-bearing\udelements. The behaviour of reinforced concrete beams under compressive and tensile\udmembrane action is not yet fully understood.\udIn order to investigate and quantify the structural resisting mechanisms of reinforced concrete\udstructures against progressive collapse, two large scale specimens have been tested under\udquasi-static loading. Non-linear response is then converted into dynamic response (Pseudo–\udStatic response) using the energy equilibrium approach proposed by Izzuddin et al. (Izzuddin\udet al., 2008)\udA finite element model was developed using the finite element software package ANSYS\ud11.0 in order to numerically simulate structural behaviour of RC beam-column subassemblages\udwhen load-carrying members are removed under the effect of abnormal loading.\udA macro-model based approach was used in the finite element analysis by using beam\udelements and a series of spring non-linear elements to capture the non-linear behaviour of\udstructural members associated with the redistribution of loads after column removal.\udNumerical results were compared with those obtained from the experimental program. Test\udresults showed that the RC sub-assemblages would experience three mechanism stages,\udflexural, compressive arch and catenary action stages to resist progressive collapse. Numerical\udresults showed a good agreement with the experimental results.