Experimental Study And Design Method Of Out-of-plane Elastic-plastic Stability Of Parallel Twin Arches

With the development of high strength material and the demand for large span increasing,the stable performance of parallel twin arches which are widely used in bridge engineering and civil engineering is becoming more and more concerned.At present,there are few studies on the elastic-plastic stability of the assembled double arch,which brings a lot of inconvenience to the out-of-plane stability design.In this paper,parallel twin arches with different cross section parameters under five point radial symmetric loads are taken as the research object,and the experimental research and numerical simulation are used to study the out-of-plane elasticplastic stability.The details are as follows:(1)Experimental study on out-of-plane elastic-plastic stability of parallel twin arches.In this paper,according to the characteristics of out-of-plane stability of arch,a set of loading devices specially used for experiment of out-of-plane elastic-plastic stability of parallel twin arches is put forward,and 7 groups of parallel twin arches are designed and made.The influence of cross section of main rid and transverse bracing are investigated,and strain and deformation data of the whole test are recorded.(2)Comparison between the experimental results and the finite element analysis results.According to the test model,considering the influence of initial geometric imperfections and material nonlinear,finite element model is established and analyzed by using the finite element software ANSYS,and the out-of-plane load-displacement curve,the in plane load-displacement curve,and the deformation of the whole arch are obtained.The results of the study show that the finite element method results are in well agreement with the experimental results.Comparing the ultimate bearing capacity of the finite element calculation and experimental results,the average error is only 4.5%.(3)Analysis of parallel twin arches parameters.By using the finite element software ANSYS,considering the initial geometric imperfections and material nonlinear,600 sets of parallel twin arches which contain different geometric initial defect,rise to span ratio,slenderness of main rid,cross section of transverse bracing,number of transverse bracing and length of transverse bracing are calculated.The results show that the rise to span ratio and the slenderness of main rib are the most important factors affecting the out-of-plane stability of parallel twin arches,while the length of transverse bracing is the least and negligible.The influence of the cross section and the number of transverse bracing should be considered simultaneously.(4)Calculation method of out-of-plane elastic-plastic stability of parallel twin arches.Based on the result of parameter analysis,the normalized slenderness is used to instead the equivalent slenderness.With the help of the stability coefficient curve of axial compression column in the standard of steel structure in China,a method for calculating the elastic-plastic stability bearing capacity of parallel twin arches is proposed.