The Local Joint Flexibility(_(LJF))of steel K-joints reinforced with external plates under axial loads is investigated in this paper.For this aim,firstly,a finite element(FE)model was produced and verified with the re...The Local Joint Flexibility(_(LJF))of steel K-joints reinforced with external plates under axial loads is investigated in this paper.For this aim,firstly,a finite element(FE)model was produced and verified with the results of several experimental tests.In the next step,a set of 150 FE models was generated to assess the effect of the brace angle(θ),the stiffener plate size(ηandλ),and the joint geometry(γ,τ,ξ,andβ)on the_(LJF)factor(f_(LJF)).The results showed that using the external plates can decrease 81%of the f_(LJF).Moreover,the reinforcing effect of the reinforcing plate on the f_(LJF)is more remarkable in the joints with smallerβ.Also,the effect of theγon the f_(LJF)ratio can be ignored.Despite the important effect of the f_(LJF)on the behavior of tubular joints,there is not available any study or equation on the f_(LJF)in any reinforced K-joints under axial load.Consequently,using the present FE results,a design parametric equation is proposed.The equation can reasonably predict the f_(LJF)in the reinforced K-joints under axial load.展开更多
It has been found that the fatigue life of tubular joints is not only determined by the hot spot stress,but also by the stress distribution through the tube thickness represented as the degree of bending(DoB).Conseque...It has been found that the fatigue life of tubular joints is not only determined by the hot spot stress,but also by the stress distribution through the tube thickness represented as the degree of bending(DoB).Consequently,the DoB value should be determined to improve the accuracy of fatigue assessment for both stress-life curve and fracture mechanics methods.Currently,no DoB parametric formula is available for concrete-filled rectangular hollow section(CFRHS)K-joints,despite their wide use in bridge engineering.Therefore,a robust finite element(FE)analysis was carried out to calculate the DoB of CFRHS K-joints under balanced-axial loading.The FE model was developed and verified against a test result to ensure accuracy.A comprehensive parametric study including 190 models,was conducted to establish the relationships between the DoBs and four specific variables.Based on the numerical results,design equations to predict DoBs for CFRHS K-joints were proposed through multiple regression analysis.A reduction of 37.17%was discovered in the DoB,resulting in a decrease of 66.85%in the fatigue life.Inclusively,the CFRHS K-joints with same hot spot stresses,may have completely different fatigue lives due to the different DoBs.展开更多
文摘The Local Joint Flexibility(_(LJF))of steel K-joints reinforced with external plates under axial loads is investigated in this paper.For this aim,firstly,a finite element(FE)model was produced and verified with the results of several experimental tests.In the next step,a set of 150 FE models was generated to assess the effect of the brace angle(θ),the stiffener plate size(ηandλ),and the joint geometry(γ,τ,ξ,andβ)on the_(LJF)factor(f_(LJF)).The results showed that using the external plates can decrease 81%of the f_(LJF).Moreover,the reinforcing effect of the reinforcing plate on the f_(LJF)is more remarkable in the joints with smallerβ.Also,the effect of theγon the f_(LJF)ratio can be ignored.Despite the important effect of the f_(LJF)on the behavior of tubular joints,there is not available any study or equation on the f_(LJF)in any reinforced K-joints under axial load.Consequently,using the present FE results,a design parametric equation is proposed.The equation can reasonably predict the f_(LJF)in the reinforced K-joints under axial load.
基金sponsored by the Fundamental Research Funds for the Central Universities,CHD(No.300102211303)the Scientific Innovation Practice Project of Postgraduates of Chang’an University(No.300103714019).
文摘It has been found that the fatigue life of tubular joints is not only determined by the hot spot stress,but also by the stress distribution through the tube thickness represented as the degree of bending(DoB).Consequently,the DoB value should be determined to improve the accuracy of fatigue assessment for both stress-life curve and fracture mechanics methods.Currently,no DoB parametric formula is available for concrete-filled rectangular hollow section(CFRHS)K-joints,despite their wide use in bridge engineering.Therefore,a robust finite element(FE)analysis was carried out to calculate the DoB of CFRHS K-joints under balanced-axial loading.The FE model was developed and verified against a test result to ensure accuracy.A comprehensive parametric study including 190 models,was conducted to establish the relationships between the DoBs and four specific variables.Based on the numerical results,design equations to predict DoBs for CFRHS K-joints were proposed through multiple regression analysis.A reduction of 37.17%was discovered in the DoB,resulting in a decrease of 66.85%in the fatigue life.Inclusively,the CFRHS K-joints with same hot spot stresses,may have completely different fatigue lives due to the different DoBs.
