Stability Research And Reliability Analysis Of Cylindrical Latticed Shell Structure

In this thesis,a kind of large span structure system used more and more- cylindrical latticed shell structure system is focused on, Influence of geometric nonlinear, material nonlinear, initial imperfection and section type on structural stability is comprehensive studied. Meanwhile, in view of the two different methods based on two codes for solving the designed value of ultimate bearing capacity of spatial latticed structures but now there is no document contrasting the two kinds of methods systematically, it is very necessary to inquiry the similarities and differences of the two kinds of methods. In this thesis, the two kinds of methods are contrasted in terms of reliability so this can be refered to by technicians and this is the innovation point of the thesis.Finite element theory and theories of stability and instability are used most in the analysis of the stability of cylindrical latticed shell,and the software of ANSYS are used for assistant calculation.The load-displacement curve is obtained by cylinder arc method based on which the ultimate bearing capacity of the structure is obtained.The JC method and Response Surface Method are used in the analysis of reliability.In this thesis,two engineering examples are used for assistant calculation,which are the roof single-layer cylindrical latticed shell of the new Tianjin West Station and the double-layer cylindrical latticed shell of some project.The following conclusions are obtained based on the analysis and research:(1)For the long-span cylindrical latticed shell structure,the ultimate bearing capacity obtained based on double nonlinear is obviously lower than that obtained based only on geometric nonlinear so the influence of material nonlinear on the structure is very considerable.Therefore ,the influence of double nonlinear on the ultimate bearing capacity of structure should be considered in the following anlysis.(2)Although initial imperfection has some influence on the structure,there is no significantly ultimate bearing capacity reduction when initial imperfection is considered.Therefore,the cylindrical latticed shell structure is not sensitive to initial imperfection.(3)The ultimate bearing capacity of cylindrical latticed shell structure has much to do with the section type. For general purposes, the structure with closed section has better stability than that with open section in the same condition. (4)Through the analysis of reliability,the following conclusion can be obtained: For the cylindrical latticed shell structure, the reliability of the designed value of ultimate bearing capacity obtained based on (DG/TJ08-52-2004) of Shanghai in which the Koiter Theory is used is much higher than that obtained based on (JGJ61-2003) in which full-process analysis method is used.