Numerical Simulation Analysis On The Lateral Torsional Buckling Behavior Of Steel Beams Under Transverse Impact

Steel structures have many advantages, so they are widely applied in construction engineering field. However, steel structure is not only to withstand normal design load, but also withstand strong dynamic load effect of accidental impact and explosion during the period of service. Steel beams and columns may cause the instability and the bearing capacity failure of bearing components owing to large deformation under impact, resulting in the collapse of the structure damage. Therefore, the study on the buckling of steel components under impact has very important background of engineering and receives growing attention from the academia.This paper completed experimental study and numerical simulation analysis on the dynamic response of rectangular section steel beams under the large mass impact. The experimental results show that rectangular section steel beams can stimulate lateral torsional buckling behavior under transverse impact; the lateral torsional buckling form of steel beams under impact dependent on each component itself and applied load conditions. The numerical simulation of the experiment was carried by using the general-purpose finite element program ANSYS/LS-DYNA; the numerical simulation results agree well with the experimental results, and the simulation method used in the paper can simulate the lateral torsional buckling behavior of steel beams under transverse impact. On this basis, a detailed analysis on the lateral displacement of the steel beams time history curve and the x-axis strain time history curve were completed; the results further validate the steel beams can occur lateral torsional buckling behavior under transverse impact.This paper puts forward the concept of the ratio (△/t) between displacement difference and the thickness of beams and using the value of△/t to determine the stability of the steel beams under impact loading. The critical load of the lateral torsional buckling behavior of steel beams under transverse impact is defined as the load that makes the value of△/t greater than1. Using the numerical simulation method in this paper, the parameter contained initial imperfections, geometrical parameters, impact height, impact kinetic and momentum have an effect on the lateral torsional buckling behavior of steel beams under transverse impact. The results reveal that when initial imperfection and impact height increase, steel beams under dynamic loading are prone to instability deformation. The impact momentum has an effect on the lateral torsional buckling form of steel beams. Within a certain range, when slenderness ratio of steel beam cross section on the x-axis increase, the lateral bearing capacity of steel beams under impact loading improves.Most of steel beams in practical engineering are H-shaped steel beams, therefore, the numerical simulation analysis on the dynamic response of the H-shaped steel beams under impact load was carried out by using ANSYS/LS-DYNA program. The results show that rectangular section steel beams under dynamic load are prone to instability deformation, and H-shaped steel beans under transverse impact are also likely to lateral flexion bending and twisting. The impact kinetic energy has important influence on the lateral torsional buckling of H-shaped steel beams under impact load. The impact momentum has little effect on the lateral torsional buckling form of H-shaped steel beams.