Research On Out-of-plane Bending And Torsion Buckling Of Steel Arches Subjected To Fire

With the development of modern architecture,steel arches are more and more widely used in engineering.However,due to the fire resistance of the steel arch structure,once the fire occurs,it will pose a great threat to the structure.The steel arch may torsion buckling in a fire due to insufficient out-of-plane support.At present,there are few studies on out-of-plane instability of steel arches exposed to fire.Failure to form a perfect theoretical system has limited the application of arched structures in more areas.To improve the research on the buckling behavior of the arch under the high temperature of the fire and enhance the fire resistance of the steel arch structure in the project,this paper uses ABAQUS finite element software to target the circular arc steel arch under different loads and complex boundary conditions under high temperature of fire A series of studies have been carried out on the out-of-plane torsion buckling problem.This study introduces the finite element analysis method used,studies the influence of different geometric defects on the calculation results,and conducts mesh convergence analysis.According to the experimental results in the literature like the research object of this study,the finite element verification is carried out,which proves the correctness of the establishment method of the finite element numerical model adopted in this study.Then for the H-shaped arc steel arch under the concentrated load in the middle of the span and the uniform load in the whole span,the load-displacement curve of the model was obtained,and the limit load of torsion buckling at normal temperature was obtained from the curve,and the arch The influence of the vector-span ratio and the two support forms on the ultimate load.Then according to the obtained limit load,the structure is loaded with three different load ratios,and the standard heating curve is used to heat the steel arch.The displacement change curve and temperature displacement curve of the model during the heating process are obtained,and the critical temperature is obtained.The effects of load ratio,vector-span ratio and bearing form on the critical temperature of torsion and buckling of fired steel arches are studied.Using the validated finite element numerical method,the out-of-plane stability of the fired steel arch under complex boundary conditions is studied.Converting different complex boundaries into models with different rotational stiffness,and by changing the in-plane and out-of-plane rotational stiffness at the boundary,many models were established and parameter analysis was carried out.The relationship between the ultimate load of torsion buckling and the rotational stiffness of the boundary at normal temperature for steel arches with different vectorto-span ratios was studied,and then the effect of different boundary rotational stiffness on the critical temperature of the torsion buckling of the steel arch plane under high-temperature fire was analyzed.According to the results of the parameter analysis,the law of the rotation ability of the arch foot to the ability of the structure to resist instability under fire is summarized.The experimental plan of the completed design is introduced,the difficulties in the steel arch fire resistance experiment are summarized,and the verification method of each component in the experimental process using the finite element method is discussed.The detailed analysis of the experimental design scheme completed in this study verifies that the components in the scheme can complete the experimental work well.