Stability Study Of Hollow Truss Arches

At present,the steel arch as the main bearing member has been widely used in engineering projects.The research object of this paper is the circular steel tubular Vierendeel truss arches with rectangular section,without diagonal tubes.The in-plane elastic buckling performance and elastoplastic stability bearing performance,out-ofplane elastic buckling performance and elastoplastic stability bearing performance of circular steel tubular Vierendeel truss arches with rectangular section are studied.Some design formulas for stable bearing capacity are summarized for practical engineering reference.According to the force characteristics of the truss section,the section stiffness of Vierendeel truss arches with rectangular section is theoretically deduced,including tension and compression stiffness,in-plane bending stiffness and in-plane shear stiffness.By considering the influence of shear deformation,the shear stiffness is substituted into the equilibrium equation to obtain the in-plane elastic buckling load of pin-ended circular steel tubular Vierendeel truss arches with rectangular section under uniform compression.With reference to the stability design method of the axial compression column,the finite element model is analyzed by nonlinear elastoplastic analysis,a normalized slenderness ratio and reduction factor are introduced to establish the in-plane stability curve of the arch under uniform compression.On this basis,the in-plane failure mechanism,mode and elastoplastic stability bearing capacity of the arch under a full-span uniform vertical load and a half-span uniform vertical load are further studied.For global failure mode,it is suggested to use the binomial of the integral axial force and the bending moment to design and calculate the in-plane global stability bearing capacity of circular steel tubular Vierendeel truss arches with rectangular section under the actions of combined axial compression and bending.Different local failure modes have been studied by changing the stiffness of the transverse tube.For chord local failure mode with superior deformation and bearing performance,it is recommended to use the strength design formula of axial force and bending moment to check the local bearing capacity.The section stiffness of Vierendeel truss arch is obtained by theoretical deduction,including out-of-plane bending stiffness,out-of-plane shear stiffness and torsional stiffness.Based on the out-of-plane elastic buckling theory of solid web arches,the numerical fitting method is used to respectively obtain the numerical solutions of the out-of-plane elastic buckling load of circular steel tubular Vierendeel truss arches with rectangular section under uniform compression and uniform bending moment.With reference to the stability design method of the axial compression column,the finite element model is analyzed by nonlinear elastoplastic analysis,by introducing pure compression normalized slenderness ratio and pure bending normalized slenderness ratio to establish the out-of-plane stability curve of the arch under uniform compression and uniform bending moment.On this basis,the out-of-plane global elastoplastic stability bearing capacity of the arch under a full-span uniform vertical load and a halfspan uniform vertical load are further studied.For global failure mode,it is suggested to use the binomial of the integral axial force and the bending moment to design and calculate the out-of-plane global stability bearing capacity of circular steel tubular Vierendeel truss arches with rectangular section under the actions of combined axial compression and bending.