Experimental Study And Numerical Simulation Of High Strength Concrete RC Beam Under Impact Load

In recent years, terrorist attacks and serious explosions are posing an increasing threat to ordinary people and public property. Besides, Natural disasters such as earthquake, tsunami, debris flow, and the resulting secondary disasters destroy buildings and endanger people's life and property safety. Due to the extensive application of reinforced concrete structure around the world, it is necessary to study its mechanical behavior and failure characteristics under impact load. As an important structure member, reinforced concrete beam need to be designed with consideration of the effects of impact and blast loads.The failure pattern and crack profile of normal reinforced concrete beam under impact load have been basically investigated in previous studies. But with the application of the high strength concrete in the structure, Impact properties of high strength concrete RC beam need to be further researched. This paper basically studies the behavior of the high strength concrete RC beam under impact load. A series of high strength concrete RC beam species are designed with the aim of studying the resistant ability, the impact force, the supporting force, the displacement of the middle span, the crack and failure mode under impact loading. A high-performance drop-weight machine is used in the experiment. The variables include ratio of stirrup, impact energy and concrete strength. Meanwhile, cracking propagation and the failure process of the beams were monitored using a high-speed video camera. Time histories of longitudinal rebar strain, stirrup rebar strain, impact force, support force and midspan deflection were recorded. The experimental results show that the difference of stirrup ratio and concrete strength could change cracking mechanism of the high strength concrete RC beam. The middle-span displacement could be reduced effectively with the increase of stirrup ratio.Based on the experiment, numerical simulation analysis is conducted by using commercial explicit dynamic finite-element software LS-DYNA. The finite-element analysis results agree well with the experiment, including time histories of mid-span displacement, impact force and support force. But the damage characteristics can not be predicted well due to the defect of concrete material model, which need to be further improved. Moreover, the parameter analysis is conducted including the concrete strength, drop weight, stirrup ratio and impact velocity.