Analysis Of Double Twist Rectangular Steel Tube For Progressive Collapse

With the continuous progress of the society and the economy developed rapidly,the large-span reticulated shell structure is favored by more and more people.This paper researches on the double twist reticulated shells.The following work has been done:(1)The seismic nonlinear time history analysis and wind load analysis are carried out for the double twist rectangular steel tube roof.The key members of the structure are preliminarily determined according to the results of the analysis.Based on the geometric nonlinearity and material nonlinearity,the force performance of the key joint of the reticulated shell is analyzed.The model of straight rectangular steel tube with the same size of key rod is established.The plastic development and buckling form of the two kinds of joints are studied.(2)Analysis of the strong wave action of EL-centro wave and Tianjin wave on double twist reticulated shells with three support structure(frame brace combined column brace,frame brace and without pedestal).According to the principle of dynamic incremental method,the acceleration amplitude is continuously increased,and the whole plastic development process of the double twist reticulated shells under strong earthquake is observed.The displacement response of the node and the plastic rate of the rod are analyzed,and the acceleration amplitude of the double twist reticulated shells is determined in the form of different supporting structures,and the anti collapse and failure mechanism of the double twist reticulated shells with different support structures is compared.(3)Based on concept judgement,double nonlinear buckling analysis of double twist reticulated shells is carried out.The sensitivity of rods and joints is calculated in response to ultimate bearing capacity.At the same time,the influence of the cross section(rectangle and round)of the double twist reticulated shells and the lower support structure(frame column and column slanting combination,frame column and base without base)on the sensitivity of the key members and nodes was analyzed.(4)The progressive collapse resistance of double twist rectangular steel tube reticulated shell structures is studied by the demolition member method.Based on the criterion of structural strength failure and instability failure,the progressive collapse resistance and failure mechanism of double twist rectangular steel tube reticulated shell structures are discussed.