Dynamic Response And Damage Analysis Of Steel Fiber Reinforced Concrete Box Girder Subjected To Blast Load

In recent years,the explosion caused by terrorist attacks and accidents have seriously affected the normal use of bridges and the safety of people's lives and property,the study of antiknock performance of bridge structures is a very urgent subject.At present,it is still the primary task to study the dynamic response of the basic components under the explosive load,and the steel fiber reinforced concrete as a new type of anti-blast protection material has been paid more and more attention,but the study of its components under the impact of explosive load is not systematic.In this paper,the dynamic response and damage effect of steel fiber reinforced concrete box girder under explosive loading are systematically studied by model test and numerical simulation.The main contents and achievements are as follows:(1)The research status,the existing research results and existing problems of steel fiber reinforced concrete under the impact of explosion both at home and abroad are summarized,the phenomenon of explosion and the basic theory of explosion wave are studied systematically,the parameters of explosion shock wave that come from the empirical formula are summarized,and the damage mechanism of the bridge structure is analyzed.(2)The material characteristics and dynamic and static constitutive relations of steel fiber reinforced concrete are analyzed,the effect of strain rate effect on the properties of the material under the impact of the explosion load and the solution in the numerical simulation are put forward.(3)The dynamic response of ordinary concrete small box girder and steel fiber reinforced concrete small box girder under different load conditions was studied by comparison experiment,the effects of explosive dosage,explosion height and location on the dynamic response of small box girders were obtained by analyzing the strain and acceleration data collected during the experiment,the damage degree of the structure under different load conditions is obtained by ultrasonic inspection of concrete.(4)The dynamic response of steel fiber reinforced concrete box girder under explosive loading is simulated by ANSYS / LS-DYNA,and obtained the similar laws by comparing the numerical simulation results with the experimental results.The results show that the top and flange plates are most susceptible to damage,especially the roof,and the dynamic response of the structure is more sensitive to the height of the explosion.The incorporation of steel fibers into concrete is of great help to improve the antiknock performance of the structure.