Damage Effects Of H-section Steel Column Subjected To The Combined Effect Of Close-range Blast And Fragments

In recent years,terrorist attacks,local wars and explosions have frequently happend in various parts of the world.The targets of terrorist attacks were military and government buildings in the past,but the targets are gradually changed to the ordinary civil buildings in recent years.As the steel structure is widely used in the civil construction,steel column was rearged as the main bearing structure and it's anti-explosive ability is directly related to the entire structure's anti-explosive level.Therefore,it is of great practical significance to study the anti-blast ability of steel column.In this paper,ANSYS/LS-DYNA software is used to simulate the damage of H-section steel column under blast waves and prefabricated fragments.The main work and results are as follows:(1)A numerical model consisting of explosives,fragments,air,steel column and rigid floor was built.Through numerical simulation,such as explosion-driven metal plate,explosive shock wave effect on steel plate and combined load on steel plate,some comparative analysis were carried out between the theoretical formula and experimental data.The rationality of coupling algorithm,contact type and constitutive model were verified.(2)The dynamic response of H-section steel column under different loads were analyzed.The reaults show that the destruction mechanisms of shock wave and fragments are different.The shock wave mainly causes the deflection of the steel column,while the fragmens mainly causes local erosion.The combined load is bigger than the linear superposition of single load effect,the destruction effect has a superposition enhancement effect.The steel column was first subjected to the shock wave effect and then to the impact of the fragments in the close-range explosion.(3)The dynamic response of H-section steel column under the combined effect of shock wave and fragments was studied by parameter method.The reaults show it should be reasonable to choose steel strength in the antiknock design,and the high-strength steel should not been blindly choosen;under the same amount of steel,tubular cross-section steel column has the best anti-blast ability,H-section is the second,and the box section is the worst;In order to improve the anti-explosive ability of steel column,the section type should to designed to make the width of flanges lessthan the hegiht of web;Thicker web thickness,smaller width-to-thickness ratio of flanges and smaller height-to-thickness ratio of web are beneficial to improve the anti-blast ability of steel column.(4)The effect of load parameters on the anti-blast performance of H-section steel column under the combined loads were studied.The results show that the explosions should be considered as the major factor in the anti-explosive design of steel column;In the scale distance formula,with the increase of the distance factor R,the effect of the failure of the steel column showing convergence effect;With the increase of the quantity of explosions,its destructive effect is not a simple linear superposition,the destruction effect has the superposition enhancement effect;The effect of the height of the explosive on the anti-blast performance of the steel column is different;In the anti-blast design of steel column,it should control the value of the axial pressure,and the axial compression ratio should not bigger than 0.4;The CFRP material which stick to the H-section steel column has a good protective effect.