Study On Explosion Resistance Of High Strength H-type Steel Beam

High strength steel has been gradually applied in large public buildings and infrastructure at home and abroad,showing broad application prospects.Due to the terrorist attacks,accidental explosions and other explosive threats,the anti-explosion performance of the structure is directly related to the safety of people’s lives and property.However,there are few researches on the dynamic characteristics of high strength steel and the anti-explosion properties of high strength steel structures.In this paper,the anti-explosion performances of Q460JSC and HQ600 high-strength H-type steel beams were investigated by experimental research and numerical simulation.The main work and conclusions are as follows:1.The dynamic tensile tests of Q460JSC and HQ600 high-strength steels were carried out.The dynamic mechanical properties of these two kinds of steels in the range of 10^-3～10³strain rate were obtained by combining the test results and numerical simulations.The modified Johnson-cook model was used to fit the test results to obtain the constitutive model parameters.Tensile tests for notched specimens of these two kinds steels were carried out as well,and Johnson-cook damage model parameters were calibrated.2.The anti-explosion tests of H-beams of high-strength steels（Q460JSC and HQ600）and ordinary steels（Q345B）were carried out.The law of shock wave propagation and the dynamic response of steel beams under explosion were studied.The effects of proportional distance,steel strength and direction of explosion on the steel beams anti-explosion properties were analyzed..The results show that under the condition of near-explosion,the prediction peak of the empirical formula for over-pressure is generally smaller than the experimental value;the smaller the proportional distance,the higher damage degree of the steel beam.Under the same kind of explosion distance conditions,both high-strength steels exhibit superior anti-explosion performance than ordinary steel;H-type steel girder webs have poor anti-explosion performance in the normal direction,and should be considered to enhance in anti-explosion design.3.The LS-DYNA finite element software was used to simulate the anti-explosion performance of high-strength H-beams.The modified Johnson-Cook constitutive equation and its damage criterion were used,the simulation results were compared with the experimental results.The reliability of the simulation method is verified,and the effects of constraints,proportional distance,section type,high span ratio,width-thickness ratio and other factors on the anti-explosion performance of high-strength steel beams are further studied.The results show that the two high-strength steel beams have better anti-explosion performance than the ordinary steel beams under the same working conditions;the H-shaped steel beam restraint is strengthened,the proportional explosion distance is reduced,the heigh-span ratio is increased,and the section width is reduced can reduce the deformation and damage of the steel beam to certain extent.