Study On Impact Resistance And Dynamic Failure Criterion Of Circular Tubular T-joints

Steel tubular structure has been widely used in various building structures due to its unique structural and architectural advantages.But,with the occurrence of natural disasters and accidents,steel tubular structure building accidents happen frequently around the world,which makes the impact resistance evaluation and safety design of engineering structures become a hot spot.As a key part of the steel tubular structure,the impact resistance of tubular joints largely determines whether the steel tubular structure has good impact resistance.Although the research on tubular joints under static load is becoming more and more abundant,the research on the impact resistance mechanical properties of tubular joints is still insufficient.Considering the beauty and applicability of the circular steel pipe and the typicality of the T-joint,this paper uses the finite element analysis software ABAQUS to nonlinear numerical simulation research on the mechanical properties of circular tubular T-joints,On this basis,combined with the static bearing capacity of the joint,the failure criterion of the impact resistance bearing capacity of tubular T-joints is proposed.The main contents of this paper are as follows:（1）The influence of the diameter ratios of brace and chord（β）on the impact resistance of circular tubular T-joints was studied by using finite element analysis software.Through the analysis of the failure mode of joints,impact force and displacement time-history curves,strain time-history curve and energy dissipation time-history curve,the impact resistance failure mechanism of circular tubular T-joints was revealed.Finally,the force transmission mechanism of tubular T-joints were analyzed in depth based on the inertia effect on the distribution of bending moment and shear force under static force and impact load.（2）Based on the numerical simulation,the domestic and foreign standard formulas under static force were summarized and analyzed,and the simplified analysis method of equivalent impact force using plastic hinge line and energy theory was compared.The failure criterion of 3%D（chord diameter）under static force is enlarged,and the local depression of 8%D is proposed as the dynamic failure criterion for circular tubular T-joints,and the comparison and verification are carried out.