In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stre...In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.展开更多
The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specim...The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specimens, moment-vertical displacement curves, moment-deformation of the chord, and strain strength distribution curves were presented. The effect of β and plate reinforcement types on in-plane flexural property of SHS X-joints was studied. Results show that punching shear of chord face disappears, brace material fracture appears and concave and convex deformation of chord decrease when either collar plates or doubler plates were welded on chord face. Moment-vertical displacement curves of all specimens have obvious elastic, elastic-plastic and plastic stages. As β increases, the in-plane flexural ultimate capacity and initial stiffness of joints of the same plate reinforcement type increase, but ductility of joints decreases. With the same β, the in-plane flexural initial stiffness and ultimate capacity of doubler plate reinforced joints, collar plate reinforced joints, and unreinforced joints decrease progressively. Thickness of reinforcement plate has no obvious effect on in-plane flexural initial stiffness and ultimate capacity of joints. As thickness of reinforcement plate increases, the ductility of reinforced X-joints decreases. The concave and convex deformation of every specimen has good symmetry;as β increases, the yield and ultimate deformation of chord decrease.展开更多
X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular structures.Experimental investigation of four tubular X-joints with bolted connection was conducted in this study,a...X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular structures.Experimental investigation of four tubular X-joints with bolted connection was conducted in this study,and it was found that the annular plate was the main yielding control member of such X-joints.Moreover,the portion outside the effective width of the chord member still had a restriction effect on the annular plate,which led to reducing the yielding strength of the joint,while the gusset plate could help to improve the yield strength capacity.In the current design code of steel structures,the contribution to the strength capacity of the gusset plate has not been taken into account.Therefore,based on some mechanical assumptions,a general mechanical model was proposed.After the introduction of the gusset plate strength capacity factor,the yield capacity simplified calculation method of such X-joints was derived.Through the analyses of such X-joints with various diameters and thicknesses,it was concluded that a simple mechanical model could predict test results very well and that the contribution of the gusset plate was also taken into account.展开更多
This paper introduces the influence factors of axial stiffness of tubular X-joints. The analysis model of tubular joints using plate and shell finite element method is also made. Systematic single-parameter analysis o...This paper introduces the influence factors of axial stiffness of tubular X-joints. The analysis model of tubular joints using plate and shell finite element method is also made. Systematic single-parameter analysis of tubular X-joints is performed using Ansys program. The influences of those factors, including ratio of brace diameter to chord diameter （β）, ratio of chord diameter to twice chord thickness （γ）, ratio of brace wall thickness to that of chord （τ）, brace-to-chord intersection angle （θ）, and chord stress ratio, ratio of another brace diameter to chord diameter, in-plane and out-of-plane moment of braces, etc., on stiffness of tubular X-joints are analyzed. Two non-dimensional parameters-joint axial stiffness factor ηN and axial force capacity factor ωN are proposed, and the relationship curve of the two factors is determined. Computational formulas of tubular X-joint axial stiffness are obtained by multi-element regression technology. The formulas can be used in design and analysis of steel tubular structures.展开更多
目的探讨关节镜联合C型臂X线机治疗胫骨平台骨折的效果。方法方便选择2017年1月—2022年12月丹阳市人民医院收治的78例胫骨平台骨折患者为研究对象,以随机双盲法分为两组,每组39例。对照组行常规切开复位内固定术,观察组行关节镜联合C型...目的探讨关节镜联合C型臂X线机治疗胫骨平台骨折的效果。方法方便选择2017年1月—2022年12月丹阳市人民医院收治的78例胫骨平台骨折患者为研究对象,以随机双盲法分为两组,每组39例。对照组行常规切开复位内固定术,观察组行关节镜联合C型臂X线机微创内固定术,对两组手术疗效、手术指标、膝关节功能恢复与并发症发生情况进行分析比较。结果观察组手术优良率(97.44%)明显高于对照组(82.05%),差异有统计学意义(χ^(2)=5.014,P<0.05);观察组手术治疗相关指标优于对照组,差异有统计学意义(P均<0.05)。术后6个月两组患者Lysholm、纽约特种外科医院(Hospital for Special Surgery,HSS)评分均升高,且观察组Lysholm、HSS评分明显高于对照组,差异有统计学意义(P均<0.05)。观察组术后并发症总发生率低于对照组,差异有统计学意义(P均<0.05)。结论胫骨平台骨折患者采用关节镜联合C型臂X线机治疗的疗效确切,患者创伤小、术后恢复快、并发症少,且对患者膝关节功能的恢复有着明显的促进作用。展开更多
基金The research work was financially supported by the National Natural Scientice Foundation of China(Grant No.10142001)by the Shandong Provincial Natural Scientice Foundation(Grant No.Y2006F46)
文摘In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.
基金Projects(51278209 and 51478047) supported by the National Natural Science Foundation of ChinaProject(ZQN-PY110) supported by Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University,China+1 种基金Project(2014FJ-NCET-ZR03) supported by Program for New Century Excellent Talents in Fujian Province University,ChinaProject(JA13005) supported by Incubation Programme for Excellent Young Science and Technology Talents in Fujian Province Universities,China
文摘The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specimens, moment-vertical displacement curves, moment-deformation of the chord, and strain strength distribution curves were presented. The effect of β and plate reinforcement types on in-plane flexural property of SHS X-joints was studied. Results show that punching shear of chord face disappears, brace material fracture appears and concave and convex deformation of chord decrease when either collar plates or doubler plates were welded on chord face. Moment-vertical displacement curves of all specimens have obvious elastic, elastic-plastic and plastic stages. As β increases, the in-plane flexural ultimate capacity and initial stiffness of joints of the same plate reinforcement type increase, but ductility of joints decreases. With the same β, the in-plane flexural initial stiffness and ultimate capacity of doubler plate reinforced joints, collar plate reinforced joints, and unreinforced joints decrease progressively. Thickness of reinforcement plate has no obvious effect on in-plane flexural initial stiffness and ultimate capacity of joints. As thickness of reinforcement plate increases, the ductility of reinforced X-joints decreases. The concave and convex deformation of every specimen has good symmetry;as β increases, the yield and ultimate deformation of chord decrease.
基金Project(No.ZDK023-2011) supported by the Scientific and Technical Project of Zhejiang Electric Power Company,China
文摘X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular structures.Experimental investigation of four tubular X-joints with bolted connection was conducted in this study,and it was found that the annular plate was the main yielding control member of such X-joints.Moreover,the portion outside the effective width of the chord member still had a restriction effect on the annular plate,which led to reducing the yielding strength of the joint,while the gusset plate could help to improve the yield strength capacity.In the current design code of steel structures,the contribution to the strength capacity of the gusset plate has not been taken into account.Therefore,based on some mechanical assumptions,a general mechanical model was proposed.After the introduction of the gusset plate strength capacity factor,the yield capacity simplified calculation method of such X-joints was derived.Through the analyses of such X-joints with various diameters and thicknesses,it was concluded that a simple mechanical model could predict test results very well and that the contribution of the gusset plate was also taken into account.
文摘This paper introduces the influence factors of axial stiffness of tubular X-joints. The analysis model of tubular joints using plate and shell finite element method is also made. Systematic single-parameter analysis of tubular X-joints is performed using Ansys program. The influences of those factors, including ratio of brace diameter to chord diameter （β）, ratio of chord diameter to twice chord thickness （γ）, ratio of brace wall thickness to that of chord （τ）, brace-to-chord intersection angle （θ）, and chord stress ratio, ratio of another brace diameter to chord diameter, in-plane and out-of-plane moment of braces, etc., on stiffness of tubular X-joints are analyzed. Two non-dimensional parameters-joint axial stiffness factor ηN and axial force capacity factor ωN are proposed, and the relationship curve of the two factors is determined. Computational formulas of tubular X-joint axial stiffness are obtained by multi-element regression technology. The formulas can be used in design and analysis of steel tubular structures.
文摘目的探讨关节镜联合C型臂X线机治疗胫骨平台骨折的效果。方法方便选择2017年1月—2022年12月丹阳市人民医院收治的78例胫骨平台骨折患者为研究对象,以随机双盲法分为两组,每组39例。对照组行常规切开复位内固定术,观察组行关节镜联合C型臂X线机微创内固定术,对两组手术疗效、手术指标、膝关节功能恢复与并发症发生情况进行分析比较。结果观察组手术优良率(97.44%)明显高于对照组(82.05%),差异有统计学意义(χ^(2)=5.014,P<0.05);观察组手术治疗相关指标优于对照组,差异有统计学意义(P均<0.05)。术后6个月两组患者Lysholm、纽约特种外科医院(Hospital for Special Surgery,HSS)评分均升高,且观察组Lysholm、HSS评分明显高于对照组,差异有统计学意义(P均<0.05)。观察组术后并发症总发生率低于对照组,差异有统计学意义(P均<0.05)。结论胫骨平台骨折患者采用关节镜联合C型臂X线机治疗的疗效确切,患者创伤小、术后恢复快、并发症少,且对患者膝关节功能的恢复有着明显的促进作用。
