The Dynamic Response And Damage Mechanism Of RC Frame Under Car Impact

In order to study the dynamic response,damage mechanism,failure mode and simplified model of reinforced concrete column and reinforced concrete frame structure impacted by cars,in this paper,large general analysis software ANSYS/LS-DYNA is used to establish numerical models of reinforced concrete columns with different height and reinforced concrete frame structure with different spans.Under car impact,this paper compares the effect of different parameters on the reinforced concrete columns,and analyzes the failure mode of reinforced concrete frame structure,and studies the simplified model of reinforced concrete frame structure.(1)According to the test of the light truck hitting a rigid wall,this paper verifies the reliability of the truck model.On the base of numerical simulation to the drop test of reinforced concrete beam,this paper verifies the reliability of reinforced concrete column and frame structure built in this paper.Based on numerical simulation to the test of the Ford Truck impacting the protective column,this paper verifies the effectiveness of the interaction between the car and the column.(2)Parametric studies are adopted to investigate the effects of the column height,vertical load of column top,the way of car collision on the dynamic response and damage process of reinforced concrete columns.The results show that: the higher the impacted column,the greater its dynamic response and more serious its damaged.Within a certain range,the vertical load can increase the shear capability of the impacted column to a certain extent,to enhance its anti-collision performance.But beyond a certain limit,the second-order effect of the vertical load will increase the dynamic response of the impacted column,and accelerate its destruction.When a lateral collision happens,auto body shifted and twisted,reducing the interaction forces with the impacted column.But the impacted Column damages more seriously.When a car is reversing,the trail of car impacts the reinforced concrete column more harmfully than its headstock'.(3)This paper studies the dynamic response and damage mechanisms of the corner post and side column of reinforced concrete frame structure with different spans under the different speed of car impact.The results show that: in the same speed,the corner post and side column hitted by car have the same damage process.The peak impact force is linear to the impact velocity.Our specification about the car equivalent impact force is a bit in unsafe.A bent-shear failure occurs at the bottom of impacted column and a shear failure occurs at its top.The damage and failure of the adjacent beam-column joints and the beam-slab joints is most serious.Dynamic response of the structure is partial,and only a partial collapse occurred.Impacting effects of car on the reinforced concrete frame structure is only related with the impacted column and its connected members,and not significant to the distant structure.(4)This paper studied the simplified model of reinforced concrete frame structure under car impact.An equivalent boundary condition is provided to simplify the overall framework.The results show that: the numerical model of reinforced concrete frame structure when the car impacts the corner post or the side column can be reasonably reduced to a partial structural model of car's hitting side column.When the conditions are not met,or in the case of less precision,it can be simplified to be a single column model with the column foot considered as a fixed end and its top as a hinged end.