Research On Performance Of Anti-progressive Collapse Of RC Space Frame Structure Strengthened With HPFL-Bond Steel Plates

A whole and progressive collapse for building structure may occur due to the local component or local regional lose efficacy in the course of useage. There are a lot of reasons to cause the failure of the whole component or local regional, such as explosion, fire and terrorist attack, etc. Progressive collapse for building structure often occurs suddenly, develops rapidly and damages severely, which has become the hot issue in the research of structural engineering.In order to improve the performanceof anti-progressive collapse existing structures through reinforcing has become an effective way to solve the present problem.To get the reinforcement, effect this paper studied the collapse mechanism of RC spacial frame structures and resistance through numerical simulation as well as theoretical analysis; after verifying the reliability of the numerical model based on the literature of vertical collapse experiments in RC spacial frame structures, structure reinforced collapse was also simulated. Finally, the effect of each reinforcement material was analyzed The major work and research results are obtained as follows:(1) The collapse processof experimental model was simulated by the finite element analysis software as ABAQUS.Through the comparative analysis of failure characteristics and physical variables in each stages, the numerical simulation and experimental were in good agreement with each other.(2) Based on the anti-collapse study about the RC planar frame structures the mechanism of the RC space frame structures were proposed.The collapse process can be interpreted by beam mechanism, composite mechanism and catenary mechanism, which were judged by the appearance and disappearance of plastic hinge.That was beam mechanism had no plastic hinge, while plastic hinge appeared in the composite mechanism and it disappeared in the catenary mechanism.Under some assumption, the calculation formulae of resistance force in these three mechanisms were presented and applied to each phase of the experiment.The error between calculation results and experiment tests was small to verigy the reliability of the proposed calculation method.(3) The HPFL-bond steel plates reinforcement method was adopted in the experimental model to simulate the vertical collapse process for obtaining the reinforcement effect.The process of the reinforced model was obviously lagged compared with the former model.The development speed of the crack was delayed. When the structure was damaged, the plastic hinge of the model was less than that of the former model, even the plastic hinge disappeared at the column.The overall stiffness of the model was obviously larger than before and each physical index had generally decreased by 30%. The ultimate damage degree was obviously weaker and the anti-collapse ability was significantly enhanced.(4) Parametric analysis for each reinforcement material includeing steel strand diameter, steel strength, mortar strength were carried out to study the reinforcement effect.Steel wire through the beam column joints can provide direct collapse resistance in various mechanisms due to the strong anchoring effect. Steel plate played the most important role in beam mechanism owning mainly to delay the emergence and development of crack and to control the crack width. Polymer mortar mainly enhanced the bond and force transmission effect between the steel strand and the original structure.