Progressive Collapse And Protection Of Multi-storey Frame Structure Subjected To An Explosion Inside Its Basement

The progressive collapse of structures under blast loads has attracted greatattention of many scholars and academic researchers for its speed, serious loss of lifeand property and rescue difficulty in recent years. At present, more and more publicand civil buildings seek space underground to improve the efficiency of building land,to achieve better economic efficiency and the using effects. Based on the explosivemechanics theory, the progressive collapse theory and the finite element method, thedamage mechanism and progressive collapse of the multi-storey reinforced concreteframe structure are analyzed due to an explosion in its basement withANSYS/LS-DYNA software. Then the dynamic response under the protection of thealuminum foam of the same building is also analyzed under the same conditions. Theprimary work and achievements are as follows:(1) The finite element coupling model is established using ANSYS/LS-DYNAsoftware, including Multi-storey reinforced concrete frame structure with basementusing integral model, soil around, air and the explosive. The catastrophic response ofthe multi-storey building are numerically investigated when the explosion occurrednear the middle column in the second story underground using alternative load pathmethod, direct simulation method and three-stage simulation method. By analysis andcomparison, the three-stage simulation method is illustrated practical, accurate andeconomic for the analysis of progressive collapse.(2) The damage mechanism and progressive collapse of the multi-storey reinforcedconcrete frame structure with basement using integral model are analyzed when theexplosion occurred in the different position in the basement using three-stagesimulation method. Then the dynamic response under the protection of the aluminumfoam of the same building is also analyzed under the same conditions. By analysisand comparison, it is proven that the aluminum foam has high energy absorptionefficiency and can greatly weaken the blast wave, which provide effective protectionfor the walls and columns, and then prevent the progressive collapse of the framestructure effectively.(3) The damage mechanism and progressive collapse of the multi-storey reinforcedconcrete frame structure with basement using separation model are analyzed when theexplosion occurred in the different position in the basement using three-stage simulation method. By analysis and comparison, the collapse mode of this kind ofstructure is divided into the integral collapse and the inclined collapse. The tilt valueis defined to determine the collapse mode or the tilt angle of the structure. Bycomparing the collapse speed of the structure, it can be known how serious of the lossof life and property caused by the structure collapse is when the explosion occurred inthe different position in the basement. The analysis results can also give somereference for research and engineering applications on the blast-proof of reinforcedconcrete frames with basements.(4) By comparing the progressive collapse of the reinforced concrete frame withbasement and the same frame without basement when the explosion occurred in thedifferent position, it is revealed that the soil around the basement play a positive rolein slowing down the speed of the structure collapse, and then can alleviate the disastercaused by the structure collapse.