Dynamic Response Of The Concrete Component Considering Damage Under Explosive Loads

With the spreading of terrorism, the explosion accident menaced badly the peace and safety of international society in the peace and development times. Both in the protective structure and in the industry and civil architecture, it is necessary to consider the effect of blast load . The study of dynamic response of structure under explosive loads is a concerned problem in the engineering field. The dynamic response of concrete slab under explosive loads is investigated in this dissertation. Concrete is a porous and brittle material ,there are some disfigurement in the process of pouring concrete and in the initial stage of shaping, such as capillary hole ,interstice , cranny of material and so on, namely initial damage. As a result of the effect of environment factor especially the effect of blast load, the cranny of concrete will worsen rapidly and form new damage. When the damage is accumulated to a certain extent, there will be macroscopical crack in the concrete. In the end the macroscopical crack will expand and interlace and cause the concrete slab to destroy. In addition the concrete is also a sensitive material for rate of strain. When analyzing the response of concrete slab under explosive loads, it is very necessary to consider the effect of damage and rate of strain. A theory analysis and numerical simulation on dynamic responses for concrete slab considering effect of damage and rate of strain under blast loads is performed in this dissertation, and the primary innovative work and achievements are as follows.Putting forward the main emphasis of this text, summarizing the study states about concrete slab under explosive loads, expatiating the study state and development direction about damage mechanics of concrete, summarizing and comparing the basic conception on air explosion and damage theory and damage model of concrete. Using energy analytic method, a theory analysis is performed to analyze the midpoint displacement of a clamped square slab considering the damage and rate of strain of concrete under explosion loads. It can be found the displacement of slab is reducing with the increasing of loads. The displacement of considering effect of rate of strain is smaller than not considering, the difference is about 64.2%-80.1%, The displacement of considering effect of damage is bigger than not considering, the difference is about 6.8%-7.9%? The displacement of considering the effect of both rate of strain and damage is smaller than not considering, the difference is about 61.4%-76.0%. It can be known considering the effect of damage and rate of strain is very necessary. Numerical simulation of concrete slab under explosion loads is carried by large finite element software ANSYS/LS-DYNA, using the solid 164 element type, the 111 material model (JOHNSON_HOLMQUIST_CONCRETE)and the simplified exponential load, comparing and analyzing the variety law of the Z-displacement, velocity, acceleration, Mises effective stress, energy dissipation and damage state of different node of concrete slab under different scale distance. When the scale distance for concrete slab is around 2, the effect of explosive loads to concrete slab can be ignored, the damage of slab is beginning from the edge. Compared the theory value with numerical simulation value, it can be found that the two are consistent in a certain range.