Test And Dynamic Constitutive Model Study Of CFST Column Under Blast Load

In recent years, the world terrorist attacks of explosion and explosion accidents occur frequently, and the explosion shock wave will make turbulent structures and cause structural damage, even cause the partial or overall collapse, which threat to human life and property. So, the work of blast resistance research for kinds of engineering structure is imminent,and antiknock structure has become an important subject faced by the world scientific research and engineering and technical personnel. Concrete filled steel tube(CFST) structure is a high-quality, high strength, reasonable economic component, and the characteristics of CFST structure make it has the strong ability to resist the blast load. At present, the study of CFST members under blast?impact and penetration performance is less, especially for CFST members under blast loading constitutive research is very little, but the working performance of the CFST members rely on the study of constitutive model.Therefore, it is of great theoretical and practical significance to study the dynamic response and constitutive model of CFST columns under blast load. In this paper, the antiknock performance and dynamic constitutive model of CFST columns is studied by the combination of experiment and simulation.First of all, designing eight large size CFST columns where including four square cross sections and four circular cross sections, then making the blast test. CFST columns have superior antiknock performance is verified by analyzing the failure mode and displacement time history curve after blast test, and under the condition of blast test, the CFST columns under blast load is mainly to the overall flexural deformation with cross regional local deformation, and the failure mode is mainly the bending damage. Then, through the test data to study the explosive equivalent, pipe wall thickness and sectional form of concrete filled steel tubular column antiknock performance. In addition, according to the test data to study the effect of the explosive charge, the thickness of steel tube on the blast resistant performance of CFST columns, as the explosive equivalent of CFST increases, the magnitude deformation in the mid-span increases obviously; as the thickness of steel tube of CFST increases, the magnitude deformation of the specimen in the mid-span decreases accordingly.Through the finite element software LS-DYNA established explosives, air, steel and concrete model, using fluid solid coupling method to realize the interaction between shock wave and CFST column, based on which the CFST column finite element model under blast load is established. Subsequently, the HJC dynamic constitutive model were analyzed to determine the HJC concrete constitutive model for preliminary material parameters, the HJC dynamic constitutive model is modified with the test data, and the HJC dynamic constitutive model parameters of concrete under blast load are derived. Since then by numerical simulation on the compressive strength of concrete, steel yield strength and axial compression ratio are studied with the analysis, with the increase of yield strength and compressive strength of CFST columns, the magnitude deformation in the mid-span decreases, which can effectively improve the anti explosion capacity of CFST column; along with increase of the axial pressure ratio, the magnitude deformation in the mid-span increases, and the axial pressure ratio to the CFST column of antiknock performance has little effect.