Research On Anti-blast Performance Of Steel Reinforced Concrete Column Under Blast Loading

Explosion has been occurring frequently in the world for many years.Both of whether lawless terrorist bombings or accidents caused by explosion have been brought huge threats to the social stability,personal and property security.In the aspect of building structure,as explosion happening,the explosive load might cause serious damage to the building structure.The explosion induced problems may bring damages of beams and columns in structures that make them not regularly working,even lead to progressive collapse of the building structures.Currently,steel reinforced concrete(SRC)composite columns are frequently used in the low parts of the super-rise buildings,and it is likely to become the object of terrorist bombing attacks.However,the study of anti-blast performance of SRC composite columns is limited,the study results are not yet included in the relevant provisions of the design code.Because of the high expensive price of explosion test,currently,analysis of anti-blast performance of structures or members is usually based on theoretical analysis and numerical simulation.Finite element numerical analysis has become high efficient supplementary means and important research method which eliminates the need for expensive test work,and more flexible than the theoretical analysis.For the purposes of building structure anti-blast research,the finite element numerical simulation is a kind of more economic,safer and more practical research method.In this paper,using finite element analysis software ANSYS/LS-DYNA for numerical simulation analysis on anti-blast performance of the SRC columns,the goals are to propose an analysis method for anti-blast performance of SRC columns under blast loading,understand the failure mechanism,failure mode and relevant parameters of SRC columns under the action of explosion,and lay a basic foundation for the design of these kinds of members.The main research contents are described as follows:(1)Research on a simplified blast loading calculation method for SRC columns.According to the reference literatures and research results,a simplified calculation method for applying blast loading of SRC columns is proposed through determining peaks of blast loading based on scaled distance,applying the uniformly distributed load on the blast side,and loading according to a triangle time history.(2)Nonlinear finite element numerical simulation on dynamic responses of the SRC columns under blast loading.During the simulation,strain rate effects of concrete and steel materials are considered,and the features and influencing factors of dynamic responses and damages of SRC columns under blast loading are analyzed,focusing on the effect of the concrete strength,the type of steel-section on dynamic responses and the damage degree of the SRC columns under blast loading.(3)Based on the numerical simulation,propose the failure modes of SRC columns which are divided into shear type,flexure type,and shear and flexure combination type.The classification is associated with the scaled distance of blast and boundary conditions at the ends of the columns.(4)Propose and analyze the shear stress distribution of SRC under blast loading which will lay a basic foundation for the blast damage evaluation.A shear stress distribution coefficient is proposed,and it is used to develop the relative shear stress,maximum shear stress,and maximum mid-span displacement in four different explosion cases.The work will lay a foundation for damage evaluation research in the future.