Numerical Simulation Analysis Of The Lateral Bending And Torsional Buckling Behavior Of H-shaped Steel Beam Under Impact

Steel structure is widely used in many construction fields because of its high strength,light weight,simple construction and the characteristic of economy and rationality,And the H-shaped steel beams is especially widely used.However,during construction and operation,the structure may be subjected to dynamic loads such as impact,explosion and earthquake.Once disaster happens,it will affect the normal use of buildings.When the building deformation is too large or overall instability,it may bring huge losses to human life and property,and even more serious damage.Therefore,it is necessary to study the stability of steel structures under dynamic loads.In this paper,the general-purpose finite element program Workbench ANSYS/LS-DYNA is used to analyze the final deformation modal and flexural deformation of H-shaped steel beam under impact.The simulation results are in good agreement with the test results,which shows that the numerical simulation method is feasible.On this basis,the mid-span lateral displacement curves of steel beams are further comparative analyzed,which shows that lateral flexural-torsional buckling also occurs in H-shaped steel beam with double-span restraint under the lateral impact loads.The dynamic response of H-shaped steel beam under six different impact velocities is simulated.It is found that when the impact velocity is very small and the impact energy does not reach the critical impact energy of the steel beam,the steel beam only bends.When the impact velocity increases gradually and the impact energy reaches the critical impact momentum of the steel beam,the lateral bending and torsional buckling of the steel beam will be stimulated.In order to more reasonably analyze the lateral bending and torsional buckling behavior of H-shaped steel beam under impact load,therefore,in this paper the numerical simulation of H-shaped steel beam is reasonably considered and initial yield is 1/1000 of the length of the steel as the initial defect.By comparing the impact force-time history curves?lateral and vertical displacement curves of mid-span joints at the top and bottom of steel beams,the effects of different width-thickness ratios,steel beam lengths and boundary conditions on lateral flexural-torsional buckling of H-shaped steel beam under the same impact energy,the influence of different impact velocity and impact mass on lateral flexural-torsional buckling of H-shaped steel beam under the different impact energy,the influence of different impact positions and different angles on lateral flexural-torsional buckling of H-shaped steel beam are studied respectively.