Progressive Collapse Studies Of Frame With Steel-Concrete Composite Beam Based On VFIFE Method

In recent decades,the progressive collapse of high-rise buildings occurred frequently,which not only brought huge economic losses to the society,but also caused serious casualties.Therefore,the anti-progressive collapse performance of structures has attracted extensive attention of scholars and engineers at home and abroad.At present,many experts and scholars have done a lot of experimental research and numerical simulation analysis on steel frame structure and reinforced concrete structure in the study of the anti-progressive collapse performance of structural system.However,the research on planar steel frame with steel-concrete composite beam is relatively few,so the continuous collapse resistance of planar steel frame with steel-concrete composite beam is studied in this paper.Vector form intrinsic finite element(VFIFE)is a new analysis method,which is based on the physical model of components and nodes.It defines the continuum as a group of particles,and calculates the motion of the particles according to the Newton’s second law.It shows unique advantages in solving complex problems such as large deformation,fracture and collapse.In this paper,based on the basic theory of vector finite element method and the instantaneous unloading method,a structural model is established considering the initial deformation of the structure.The parameter analysis of composite beam,the redistribution of internal force and the numerical simulation of progressive collapse of planar steel frame with composite beam are mainly studied.The main research contents are as follows:(1)The basic theory and analysis method of vector finite element method are described in detail.Based on this theory,a five-storey and six-span steel frame and a composite beam frame are analyzed separately under the action of horizontal seismic waves using MATLAB,and the correctness of the program for composite beam frame is verified by comparing with the analysis result of SAP2000.(2)The elastic analysis calculation model and the plastic analysis method of steel-concrete continuous composite beam structure introduced.According to the vertical displacement of the failure node and the rotation angle of the end of the failure span,the influences of concrete slab thickness,concrete strength grade and span-height ratio on the progressive collapse resistance of the structure are studied.(3)Considering the initial deformation,the internal force redistribution of steel frame and composite beam frame after removal of corner column,inner column and central column is analyzed by the instantaneous unloading method.The effect of column failure position on the progressive collapse resistance of the structure is studied.(4)Based on the vector finite element theory,a simplified fracture criterion is adopted and the fracture program is compiled by MATLAB to simulate the collapse process of steel frame and composite beam frame under vertical uniform load and horizontal earthquake respectively.By comparison,the influence of the frame with composite beam on the collapse process of the structure is analyzed.