Studies On In-plane Stability And Design Of Pin-ended Circular Steel Arches Accounting For Plate Local Buckling

Steel arches are widely used in various kinds of space structures for their good mechanical characteristics.However,the stability theory of steel aches still stays in the stage that the local buckling is not allowed to occur,and the corresponding in-plane stability design method has not yet been established completely.This paper presents a numerical investigation of the in-plane elastic stability and inelastic stability for pin-ended circular steel arches,focusing on considering plate local buckling of welded hollow section and I-section,and the corresponding in-plane inelastic stability design method is proposed.A shell element model is adopted firstly to investigate in-plane linear elastic buckling and nonlinear elastic stability of the steel arches subjected to their plate local buckling.Welded hollow section and I-section are investigated theoretically and numerically,respectively.Linear elastic buckling mode and buckling performance of circular steel arches subjected to plate local buckling are studied,and the influence of the rise-to-span ratio,the slenderness of the arch,the heightto-thickness ratio of the web,the width-to-thickness ratio of the flange as well as the flange-to-web thickness ratio are also studied.With the influence of plate local buckling,it is found that the nonlinear elastic buckling mode is changed,the original global buckling has changed into local and overall interaction buckling.it is also found that the elastic load-carrying capacity decreaeaes significantly.Based on the results obtained,the reduction coefficient of elastic load-carrying capacity of the steel arches is proposed to evaluate the influence of their plate local buckling.The failure mechanism of the welded hollow section and I-section pin-ended steel circular arches is analyzed by using a shell element model in the large deflection elastic-plastic range.The arches are investigated numerically under different load cases,associated with their initial geometric imperfection and residual stresses.It is found that the steel arch may fail owing to its local plate failure,its global failure,or its local and global coupled failure.These failure modes of the steel arches are determined by the rise-to-span ratio and the slenderness of the arch,as well as the height-to-thickness ratio of the web,the width-to-thickness ratio of the flange,the aspect ratio of the cross section,and the flange-to-web thickness ratio.The stability coefficients of the steel arches are further related to only two normalized parameters,such as a normalized height-to-thickness ratio of section and a normalized slenderness of arch.Finally,accordingly the design formula of the stability coefficients of the steel arches with plate local buckling is developed that is related to the normalized height-tothickness ratio of section and the normalized slenderness of arch.Considering the different combination of the uniformly distributed full span load and the uniformly distributed half span load,an interaction design formula is proposed for predicting in-plane strength of the steel circular arches under general in-plane loading.