Research On The Progressive Collapses Resistance Performance Of Reinforced Concrete Frame Structure Including Effects Of Infill Walls

Since the sixties of the last century, Building structures often due to an accident occurs the progressive collapse with enormous life and property loss, which attracted attention of the engineering community. For over50years, progressive collapse resistant construction has achieved a lot and several mature specifications been formulated. However, China started late in this field and the relevant specifications are still not systematic and comprehensive, especially for the resistance to progressive collapse design requirements of the most common reinforced concrete frame structure are not detailed enough, far from taking into account the effect of infill walls. Paper analyzes the progressive collapse of pure frame structure and infilled frame structure, to study the progressive collapse resistance performance of reinforced concrete frame structure and the effect of masonry infill walls, and explore the progressive collapse resistance performance of frame structure when the lower part of structure exist a weak layer.SAP2000is used for simulating the progressive collapse of plane frame with nonlinear static method, and compares it with experimental results. Studies show that:SAP2000software can simulate the early progressive collapse behavior of frame structure well and the results are somewhat conservative; Paper based ANSYS software analyze the infill walls and frame structure how to work together under vertical loads, which show that the force mechanism of infilled frame structures under vertical loads is very similar with force mechanism under horizontal load, and the simplified calculation model of infill walls can select equivalent bracing model to simulate.According to above analysis, Paper based on the alternate load path method analyzes the progressive collapse behavior of pure frame structure and infilled frame structure with nonlinear static and nonlinear time history method, to study the progressive collapse resistance performance of reinforced concrete frame structure and the effect of infill walls. Studies indicates that pure frame and infilled frame structure show the same regular pattern of collapse when the first floor columns become invalid:corner column failures most likely to make the structure collapse, the second is side column and interior column is the last one; frame column and two layers of cross-beam adjacent to failure column are the main component to bear the vertical impact load. The collapse probability of remaining structure including effects of masonry infill walls reduce obviously in the same column failure conditions. The presence of infill walls not only can absorb some impact energy, but also give the vertical impact load a wider range of internal force transmission and energy dissipation mechanisms, and pass the vertical load of failure cross to other components more better, which is more favorable to the stability of remaining structure.Analyzing the progressive collapse of frame structure which have weak layer on the first and second layer with nonlinear static and nonlinear dynamic method. The results show that the stability of remaining structure has no effect when the bottom layer exist weak layer, while the second floor is extremely detrimental to the stability of remaining structure in the weak layer and structure is prone to progressive collapse.