Mechanism Of Temperature Under Concentrated Force On Nonlinear Buckling In Circular Shallow Arch

Arch structures are widely used in the fields of bridge engineering and building engineering for its large span and high bearing capacity as well as beautiful appearance.However,arches are under compression,indicating that the buckling would be a crucial factor for design.This paper is focused on the nonlinear in-plane elastic buckling of circular shallow arches that are subjected to both a uniform temperature field and a central concentrated load.A series of innovative research are carried out by theoretical analysis,numerical simulation and model test.(1)Theoretical derivation of the nonlinear in-plane buckling critical of circular arches subjected to both a uniform temperature field a central concentrated load.The minimum potential principle is used to establish nonlinear equilibrium equations and buckling equilibrium equations,and analytical solutions for the limit buckling and bifurcation buckling loads under the temperature field are obtained.The nonlinear in-plane elastic deformation of circular arches is depicted in the whole loading produce.Base on the FEM,accuracy of the theoretical results are verified.(2)Parametric analysis of the nonlinear in-plane buckling of circular arches.The effects of uniform temperature field and rise-span ratio on the limited bucking load of circular arches are studied.The variation trends of nonlinear buckling behavior under different uniform temperature fields are investigated,illustrating the internal force and deformation variation of circular arches during the buckling process.It is found that the equilibrium path of the pinedpined circular arches is completely complicated.As the slenderness of the arch increases,pinended circular arches will have multiple limit points,while fix-ended circular arches usually only have one up limit point and one down limit point.Therefore the bucking modes of pinended arches comparing to fix-ended are much more complicated.(3)Experiment research of in-plane nonlinear bucking of circular arches.An experiment scheme is made for the research on the in-plane nonlinear elastic buckling of fix-ended arch under coupling load.The in-plane buckling experiments of arches with 1/8,1/10,1/12 and 1/14 are carried out under different temperature field.Displacement-control load method is proposed in the experiments.By comparing with finite element results and theoretical solutions,it is shown that fix-ended circular arch will buckle in an in-plane symmetric mode,which is in accordance with t theoretical ones.Furthermore,experiment results agree with theoretical analysis when the temperature load is lower than 80?.