Damage Mechanism And Progressive Collapse Of Reinforced Concrete Structure Subjected To An Explosion Inside Its Basement

The progressive collapse of structures under blast loads has attracted great attention all over the world for its short duration, large-scale destruction, serious loss of life and property and so on. Because of its functional and economic advantages, the basement is widespread in the modern buildings. In view of the complexity of progressive collapse of the building due to an explosion in its basement and in base of many references, dynamic response and damage modes of reinforced concrete column in the basement under blast loading are studied in the paper, then the damage mechanism and progressive collapse of multi-storey building due to an explosion in its basement are discussed in depth. The primary work and achievements are as follows:(1) In this paper, a general introduction about damage modes of structural components and progressive collapse of structures under blast loading is made first. By studying current research methods of progressive collapse and combining with function of explicit dynamic analytical software LS-DYNA, a new method called"Three-Stage Method"with precision and efficiency is proposed. Comparison with the direct simulation method and the alternative load path method, the method in the paper is proved to be rational and effective.(2) Dynamic response and damage modes of key reinforced concrete column in the basement under blast loading are studied. By using LS-DYNA software, various coupling models of system, including air, high explosive, reinforced concrete column and the neighboring enviroments are established. Through the research on dynamic response and damage modes of RC column when the explosive is in different relative position,the main damage modes when the explosive is close to column can be summed up as: local punching damage and general direct-shear damage. Parametric studies are adopted to investigate the effects of column parameters on dynamic response and damage modes of RC columns.(3) The progressive collapse of a reinforced concrete frame caused by an explosion in its basement is analysed using the"Three-Stage Method". By establishing the finite element model including reinforced concrete frame with basement, soil around, air and the explosive, the catastrophic collapse mechanism of a reinforced concrete frame with different storey heights, different spans and different relative position between the explosives and column is studied. In contrast to collapse mechanism of reinforced concrete frame on the ground, we find the soil around the basement can ease the disasters of progressive collapse.The analysis results in this paper can also give some reference for research and engineering applications on the blast-proof of a single column and the resistance of progressive collapse of reinforced concrete frames with basements.