Research On Structural Anti-collapse Performance And Reinforcement Of Key Rods In Shell Structure

More and more problems occur to cylinder shell structure in engineering and cases related to the collapse of the entire grid structure caused by the failure of key bars in engineering can be seen often with the wide application of cylinder shell structure in practical engineering.The characteristics of this type of buildings such as the large investment,long service life and high population,etc.,determine the extremely serious consequences,the great economic losses and the numerous bad social influences once continuous collapses occur.The multiple statically indeterminate structures of the long-span grid structure with numerous bars will produce the great non-linear mechanical behavior under extremely heavy load,which makes the judgement of grid structure collapse become extremely difficult.As a result,judging the collapse resistance performance of a structure through the collapse analysis of grid structure contains great engineering significance in practice.By taking the practical cylinder shell structure as its background,this paper uses SAP2000 finite elements analysis software and conducts theoretical derivation and numerical simulation to have systematically studied the method of key bar determination,method of bar reinforcement and grid collapse mechanism applicable to cylinder shell structure and given the criterion for judging structural seismic performance and the criterion for judging structural collapse.This paper determines the key bars in the grid through numerical simulation and analyzes the collapse resistance performance before and after bar reinforcement,and the main study work and key conclusion in this paper are as follows:(1)In this paper,the default plastic hinge model of SAP is modified with the consideration of instability of the push rod so as to make the simulation result get close to the actual pressure performance.Besides,pushover analysis of the actual grid model is conducted under different load modes,key bars and weak parts in the cylinder shell structure are determined according to the order in which the plastic hinge is produced by the bars,and specific steps applicable to the cylinder shell structure in determining the key bars are given.(2)This paper systematically discusses the method of grid structure bar reinforcement,determines the key bar reinforcement method applicable to the cylinder shell structure,replaces the original Q235 bars with Q345 bars to enhance the overall structural stability and collapse resistance performance,conducts comparative analysis of the grid collapse resistance performance before and after reinforcement,and verifies the effectiveness of the reinforcement method.(3)This paper simulates grid collapse by combining static analysis and dynamic analysis so as to evaluate the grid collapse resistance performance.In terms of static analysis,this paper mainly conducts characteristic value buckling analysis under linear load and uniformly distributed load so as to obtain the buckling load under different load modes;in terms of dynamic analysis,this paper mainly conducts time-history analysis under different seismic direction combinations and conducts time-history analysis under simple harmonic load through using incremental dynamic analysis(IDA)so as to determine grid seismic performance and dynamic acceleration in grid collapse.Specific standard used to judge grid seismic performance and specific standard used to judge grid collapse are given.