Impact Resistance Of Composite Beam And Steel Vierendeel Plate

The steel-concrete composite beam and steel vierendeel sandwich plate structure have better bearing capacity,high ductility and faster construction.Especially,the advantages of fast construction speed can meet the requirements of modern civil air defense engineering construction in wartime and the protection engineering in the construction.In addition,the impact energy can effectively dissipated by sand cushion.Therefore,the roof of the protective structure and civil air defense project is covered with a certain amount of sand layer.With the attention of accidental loads such as impact load and explosion load,the study of the impact resistance of steel-concrete composite beams and steel vierendeel sandwich plate structure covered with sand cushion has important theoretical significance and engineering value.It can provide reference for steel-concrete composite beam and steel vierendeel sandwich plate structure used in protective structure and civil air defense projects.In this paper,the mechanical behavior,failure mode,maximum impact force and sand energy consumption of steel-concrete composite beam,steel vierendee beam and steel vierendeel sandwich plate structure covered by sand cushion are studied based on the method of combining the experiment and numerical analysis.The main contents of the study are as follows:(1).The research status of soil and soil-structure combination under impact load is summarized.The reason why the less existing research about the impact resistance of steel-concrete composite beam and steel vierendeel sandwich plate structure covered with sand is analyzed.2.The impact resistance of reinforced concrete beam covered by sand and soil impact by falling body is analyzed by SPH-FEM method.The applicability of the method is verified by experimental data.Taking the diameter of the spherical body and the impact velocity as the variables,the maximum impact force of falling body in the four different soils is studied by SPH-FEM method.The results provide a stable numerical simulation method for the later analysis of the impact dynamic behavior of soil or soil-structure association.3.Sand is a good energy dissipation material.Strong extrusion and friction occur between sand particles under impact load,which reduces the impact force transmitted to the lower structure.In order to study the function of sand and the impact dynamic response of steel-concrete composite beams,six impact experiments and SPH-FEM models of steel concrete composite beams covered by sand are carried out,which sand cushion and impact energy are parameters.The analysis shows that SPH-FEM model can be used to study the impact resistance of steel-concrete composite beam covered by sand.It is concluded that the energy dissipation of sand is obvious by fracture distribution pictures of slab.Taking the thickness of sand cushion,impact energy of falling body,reinforcement ratio of the slab,the thickness of the slab,stiffness of steel beam and span of composite beam as parameters,the mid-span displacement,failure mode and crack distribution of concrete slab,energy consumption of sand and maximum impact force formula were studied by a large number of numerical models.4.The failure mode,crack distribution,deflection and maximum impact force of the steel vierendee beam are obtained based on the impact analysis of the steel vierendee beam covered with sand.It is found that transverse tensile failure of the concrete slab is the main failure.The parameterized analysis of an orthogonal and ortho-laid steel vierendeel sandwich plate structure is carried out.The influence of the thickness of sand cushion,impact energy of falling body,the thickness of the concrete slab,the ratio of moment of inertia between rib and shear connector,the length of rib and the mesh number are stuied in the maximum impact force and sand energy.The research provides a reference for the design of the orthogonal and ortho-laid steel vierendeel sandwich plate structure.