国际期刊导读

采用有限元方法,对冷弯不锈钢方管、矩形管支撑和弦杆中的T型、X型及预应力X型节点进行数值分析。考虑几何非线性和材料非线性,获得节点承载力、破坏模式及荷载-位移曲线。利用试验结果,对T型、X型矩形管、方管节点的非线性有限元模型进行修正,直到有限元结果和试验结果足够吻合。采用修正后的有限元模型对172个T型、X型节点进行参数分析,研究冷弯不锈钢管节点强度和性能的影响。将数值分析和试验中获得的节点承载力与按规范计算的设计承载力进行对比。对不锈钢管结构,采用澳大利亚规范、新西兰规范计算;对碳素钢管结构,采用国际管结构发展与研究委员会设计规范和欧洲设计规范计算。通过可靠性分析,分别评价本文提出的设计方法和现有规范的可靠度。结果表明：采用本文方法计算的设计承载力更准确、更可靠。     

方管圆管混合空间钢管节点承载性能的非线性分析

以圆管为弦管,方管(包括矩形管)为支管的混合空间钢管节点,构造新颖,受力复杂,其承载力设计和计算是工程师所关注和急需解决的问题。本文采用非线性有限元方法,选用四节点等参壳元,应用自动步长增量法求解方管圆管混合空间管节点轴向受力或平面外受弯的极限承载力。程序系统在移植ADINA程序的基础上,开发了可进行T型、X型、K型和TT型管节点有限元网格剖分的前处理程序CTUBE,并编写了AutoCADADS/RX应用程序显示管节点模型受荷后的变形和应力分布。本文通过大量算例分析,回归出相关承载力计算公式,供设计人员参考。     

考虑截面圆角效应的T型方管相贯节点静力承载力研究

CIDECT的T型方管相贯节点静力承载力公式忽略了弦杆截面圆角效应,有限元计算表明弦杆截面圆角效应对节点极限承载力有一定的影响,尤其对于较大β的节点和弦杆截面圆角外半径较大的冷弯薄壁管材节点的影响更明显。为此将考虑弦杆截面圆角效应,并提出关于T型方管节点静力承载力的修正公式。     

弦管轴向应力对TX型和XX型矩形管节点轴向承载力的影响

管节点通常是弦管和支管都受到轴向力作用,弦管应力可能对节点轴向承载力有显著的影响．本文使用有限元软件ANSYS分析了弦管应力对TX型和XX型矩形管节点轴向承载力的影响,并与相应的平面T型和X型矩形管节点作了对比．采用Lu的方法判定节点承载力．结果表明,弦管拉力对节点承载力的影响可以忽略,而弦管压力则会降低节点承载力,本文计算结果与相关规范有一定差异．     

等宽T型方管节点静力工作性能与设计

采用非线性有限元分析方法研究了等宽T型方管节点的破坏模式 ,各几何参数及弦杆所受轴压荷载对节点性能的影响。将新修订的《钢结构设计规范》 (GB5 0 0 17-2 0 0 3 )中等宽T型方管节点的设计公式与国外普遍采用的设计公式、有限元计算结果及实验结果进行了比较。结果表明 ,我国钢结构设计规范给出的设计公式是合理可行的。     

K型方管搭接节点的极限承载力研究

相贯节点的强度计算是空间管桁结构设计中的一个重要方面。利用有限元软件ANSYS,考虑材料非线性和几何非线性,对K型方管搭接节点的极限承载力进行数值模拟研究,通过一些关系曲线得出搭接率及其他几何参数对节点承载力的影响。     

轴向力作用下T型方管节点的塑性铰线分析

在Murray模型的基础上 ,采用VonMises屈服准则 ,推导了在轴向压力影响下的倾斜塑性铰线承载力公式。建立了在弦杆轴向压力影响下 ,直接焊接T型方管节点抗轴压的塑性铰线模型。得出的节点承载力公式与规范 (IIW、欧洲推荐、AWS)采用的经验公式、非线性有限元计算结果及实验结果吻合较好 ,从而在理论上完善了T型方管节点的抗压塑性铰线模型     

不锈钢轴心受压柱弯曲屈曲承载力分析

为给我国《不锈钢结构技术规范》中轴心受压柱弯曲屈曲稳定部分的编制提供依据,对国外已有的同类构件的设计方法和试验研究数据进行搜集和对比。结果表明：目前的欧洲不锈钢结构设计规范和美国冷成型不锈钢结构设计规范中计算该类构件的公式均存在一定不足。依据搜集到的199个方管、矩形管、圆管、椭圆管、焊接H形钢和冷弯C型钢截面柱的试验数据,根据冷弯效应及残余应力对轴心受压构件稳定性能的影响,将构件依据截面形式分为A、B、C三类,其中方管、矩形管和冷弯C型钢为A类,圆管和椭圆管为B类,焊接H形钢为C类,三类轴心受压稳定曲线均采用Perry公式形式表达。与试验数据对比表明：采用三类曲线能较好地估算构件的稳定承载力且离散性较小。对提出的计算式进行可靠度分析,结果表明其可靠度指标β满足我国GB 50068-2001《建筑结构可靠度设计统一标准》的要求。     

冷成型不锈钢管轴心受压柱试验研究

为研究冷成型不锈钢管轴心受压柱的稳定性能,进行了国产304牌号冷成型不锈钢方管、矩形管和圆管截面,共43根轴心受压柱试验。通过对不锈钢材料、轴压短柱试件和轴压长柱试件的试验研究,得到了试件的材料力学性能和极限荷载。分析了试件的长细比、宽厚比（径厚比）对其破坏模式及变形性能的影响。结果表明：试件的宽厚比（径厚比）对其破坏模式及变形性能有较大的影响。采用GB 50018-2002《冷弯薄壁型钢结构技术规范》、欧洲不锈钢结构设计规范、美国冷成型不锈钢结构设计规范中的计算方法以及Rasmussen提出的设计方法对试验试件进行了计算,并与试验数据对比结果表明,对于圆管试件,采用三本规范计算得到的承载力均高于试验值,偏于不安全,采用Rasmussen 提出方法的计算结果与试验值较为接近;对于方矩管试件,各种方法计算结果相近,除短柱试件试验结果高于计算结果外,其余试件试验值均与计算结果吻合较好;GB 50018-2002《冷弯薄壁型钢结构技术规范》中的计算方法不能直接用于计算不锈钢管轴心受压柱承载力。     

开长圆孔轴压构件畸变屈曲承载力试验

对26根腹板开长圆孔和未开孔冷弯薄壁型钢截面轴压构件进行畸变屈曲承载力试验研究,分析构件的屈曲模式和极限承载力。利用现行国家规范GB50018-2002《冷弯薄壁型钢结构技术规范》、北美冷弯钢结构构件设计规范AISI S100-2012计算构件承载力及非线性有限元数值模拟结果与试验结果进行分析比较。在此基础上,对腹板开长圆孔冷弯薄壁型钢截面轴压构件的承载力合理计算模式进行研究。结果表明:对于中等长度腹板开孔冷弯薄壁型钢截面轴压构件主要出现局部、畸变和整体屈曲的相关作用;腹板开孔对构件畸变屈曲稳定承载力有一定的降低作用;采用折减构件有效截面面积的修正方法可计算开长圆孔构件的畸变屈曲稳定承载力。     

Design of cold-formed stainless steel tubular T- and X-joints

This paper describes the numerical investigation of cold-formed stainless steel tubular T-joints, X-joints and X-joints with chord preload using finite element analysis. The stainless steel joints were fabricated from square hollow section (SHS) and rectangular hollow section (RHS) brace and chord members. The geometric and material nonlinearities of stainless steel tubular joints were carefully incorporated in the finite element models. The joint strengths, failure modes as well as load-deformation curves of stainless steel tubular joints were obtained from the numerical analysis. The nonlinear finite element models were calibrated against experimental results of cold-formed stainless steel SHS and RHS tubular T- and X-joints. Good agreement between the experimental and finite element analysis results was achieved. Therefore, an extensive parametric study of 172 T- and X-joints was then carried out using the verified finite element models to evaluate the effects of the strength and behaviour of cold-formed stainless steel tubular joints. The joint strengths obtained from the parametric study and tests were compared with the current design strengths calculated using the Australian/New Zealand Standard for stainless steel structures, CIDECT and Eurocode design rules for carbon steel tubular structures. Furthermore, design formulae of cold-formed stainless steel tubular T- and X-joints are proposed. A reliability analysis was performed to assess the reliability of the current and proposed design rules. It is shown that the design strengths calculated using the proposed equations are generally more accurate and reliable than those calculated using the current design rules.     

Tests and behaviour of cold-formed stainless steel tubular X-joints

The paper presents a series of tests on cold-formed stainless steel tubular X-joints. The tubular X-joint specimens were tested without chord preload as well as with three different levels of preload applied to the chord members. The test specimens were fabricated from square and rectangular hollow sections as brace and chord members. A total of 32 tests was performed. High strength stainless steel (duplex and high strength austenitic) and normal strength stainless steel (AISI 304) specimens were tested. The test results were compared with the design strengths obtained using the CIDECT Guide and Eurocode for carbon steel structures. It is shown that the design strengths predicted by the current design specifications are very conservative for the test specimens calculated using the 0.1%, 0.2%, 0.5% and 1.0% proof stresses as the yield stresses. The 0.2% proof stress is comparatively more reasonable to predict the design strengths of stainless steel tubular X-joints for both ultimate limit state and serviceability limit state.     

Stress concentration factors of cold-formed stainless steel tubular X-joints

This paper describes experimental and numerical investigations on stress concentration factors (SCFs) of cold-formed stainless steel square and rectangular hollow section (SHS and RHS) tubular X-joints. Both high strength stainless steel (duplex and high strength austenitic) and normal strength stainless steel (AISI 304) specimens were investigated. The SCFs were experimentally determined under static loading by measuring the strains at typical hot spot locations using strip strain gauges. The corresponding finite element analysis was performed to simulate the non-uniform stress distribution along the brace and chord intersection region. Good agreement between the experimental and finite element analysis results was achieved. Therefore, an extensive parametric study was then carried out by using the verified finite element model to evaluate the effects of the SCFs of cold-formed stainless steel tubular X-joints. The SCFs at the hot spot locations obtained from the experimental investigation and parametric study were compared with those calculated using the design formulae given in the CIDECT for carbon steel tubular X-joints. It is shown from the comparison that the design rules for the SCFs specified in the CIDECT are generally quite unconservative for cold-formed stainless steel tubular X-joints. In this study, a unified design equation for the SCFs of cold-formed stainless steel tubular X-joints is proposed. The proposed design equation was based on the CIDECT design equation for carbon steel tubular X-joints. It is shown that the SCFs calculated from the proposed unified design equation are generally in agreement with the values predicted from finite element analysis.     

Tests of concrete-filled stainless steel tubular T-joints

This paper describes a test program on a wide range of concrete-filled cold-formed stainless steel tubular T-joints fabricated from square hollow section (SHS) and rectangular hollow section (RHS) brace and chord members. A total of 27 tests was performed. The chord member of the test specimen was filled with concrete along its full length. Both high strength stainless steel (duplex and high strength austenitic) and normal strength stainless steel (AISI 304) specimens filled with nominal concrete cylinder strength of 30 MPa were tested. The axial compression force was applied to the top end of the brace member, which was welded to the center of the chord member. Local buckling failure of brace member was the main failure mode observed during the tests. Hence, the axial compression force was then applied by means of a steel bearing plate to avoid failure of brace member. The failure modes of chord face failure and chord side wall failure as well as crushing of the concrete infill were observed. All the tests were performed by supporting the chord member of the specimen along its entire length to apply the pure concentrated force without any bending moment. The test results were also compared with design rules for carbon steel tubular structures, which is the only existing design guideline for concrete-filled tubular joints. It is shown that the design strengths predicted by the current design rules are quite conservative for the test specimens. It is also recommended that the contribution of stainless steel tubes should be included in the design rules since it has significant effects on the ultimate bearing capacity of concrete-filled stainless steel tubular T-joints.     

冷弯不锈钢管T形节点的试验研究

对冷弯不锈钢管T形节点进行试验研究,这些节点由方矩形中空截面的支撑和弦杆构成。对高强不锈钢（双相和高强度奥氏体）和普通强度不锈钢（AISI304）构件进行了测试,共进行了22个试验。试验方法：将支撑对弦杆正面所导致的全部集中力,沿试件长度施加到弦杆上。支撑和弦杆的宽度比值（β）范围为0.5～1.0,这样可以观察到弦杆正面和侧面的失效模式。将试验结果与采用澳大利亚/新西兰不锈钢结构设计标准、CIDECT和欧洲碳素钢结构设计规范的设计方法相对比。对比结果显示：采用0.1%,0.2%,0.5%和1.0%的弹性极限应力作为屈服应力,按照这些规范计算出来的设计强度略微保守。相对而言,0.2%的弹性极限应力比较适用于预测不锈钢管T形节点在使用和极限状态下的设计强度。     

Experimental investigation of cold-formed stainless steel tubular T-joints

This paper describes a test program on a wide range of cold-formed stainless steel welded tubular T-joints fabricated from square and rectangular hollow section brace and chord members. A total of 22 tests was performed. High strength stainless steel (duplex and high strength austenitic) and normal strength stainless steel (AISI 304) specimens were tested. The tests were performed by supporting the chord member of the specimen along its entire length with the pure concentrated force applied to the chord face by the brace member. The ratio of brace width to chord width (β) of the specimens varied from 0.5 to 1.0 so that failure modes of chord face failure and chord side wall failure were observed. The test results were compared with the design procedures in the Australian/New Zealand Standard for stainless steel structures, CIDECT and Eurocode design rules for carbon steel structures. It is shown that the design strengths predicted by the current design specifications are conservative for the test specimens calculated using the 0.1%, 0.2%, 0.5% and 1.0% proof stresses as the yield stresses. The 0.2% proof stress is comparatively more reasonable to predict the design strengths of stainless steel welded tubular T-joints for both ultimate limit state and serviceability limit state. In this study, it is shown that the ultimate limit state controls rather than the serviceability limit state for most of the test specimens.     

Experimental investigation and design of round ended elliptical steel tubular T-joints under axial compression

圆端形椭圆钢管是一种融合圆形和矩形截面特征优势的构件，其圆端部分可以提供良好约束，矩形部分可实现快捷连接，在桁架结构中有着良好的应用前景，然而目前尚缺乏有关圆端形椭圆钢管相贯节点的受力性能研究。为此，通过对13根圆端形椭圆钢管T形相贯节点开展轴压性能试验，研究相贯类型、主支管径比、主支管夹角和是否填充混凝土等对其破坏模式、承载力、初始刚度和延性等力学性能的影响，明确圆端形椭圆钢管T形相贯节点在支管受压作用下相较圆形或矩形钢管相贯节点的承载特征差异，揭示相贯节点的受力机理，提出圆端形椭圆钢管相贯节点的轴压承载力计算式。研究结果表明，圆端形椭圆钢管T形相贯节点表现出良好的轴压性能；支管与主管圆弧段连接的相贯节点轴压承载力分别为圆形或矩形钢管相贯节点的1.07~1.66倍，具有明显的承载优势；主管填充混凝土可使圆端形椭圆钢管T形相贯节点的轴压承载力和初始刚度分别提高75.5%~103.4%和11.9%~60.6%；通过试验结果验证，提出的轴压承载力计算式可较准确地评估圆端形椭圆钢管T形相贯节点的轴压承载力。     

圆端形椭圆钢管T形相贯节点轴压性能试验研究与承载力计算

圆端形椭圆钢管是一种融合圆形和矩形截面特征优势的构件,其圆端部分可以提供良好约束,矩形部分可实现快捷连接,在桁架结构中有着良好的应用前景,然而目前尚缺乏有关圆端形椭圆钢管相贯节点的受力性能研究。为此,通过对13根圆端形椭圆钢管T形相贯节点开展轴压性能试验,研究相贯类型、主支管径比、主支管夹角和是否填充混凝土等对其破坏模式、承载力、初始刚度和延性等力学性能的影响,明确圆端形椭圆钢管T形相贯节点在支管受压作用下相较圆形或矩形钢管相贯节点的承载特征差异,揭示相贯节点的受力机理,提出圆端形椭圆钢管相贯节点的轴压承载力计算式。研究结果表明,圆端形椭圆钢管T形相贯节点表现出良好的轴压性能;支管与主管圆弧段连接的相贯节点轴压承载力分别为圆形或矩形钢管相贯节点的1.07～1.66倍,具有明显的承载优势;主管填充混凝土可使圆端形椭圆钢管T形相贯节点的轴压承载力和初始刚度分别提高75.5%～103.4%和11.9%～60.6%;通过试验结果验证,提出的轴压承载力计算式可较准确地评估圆端形椭圆钢管T形相贯节点的轴压承载力。     

平面X形圆钢管混凝土节点平面外受弯性能试验研究

为了解平面X形圆钢管混凝土节点的平面外受弯性能,分别对4个主管填混凝土和4个支管填混凝土的平面X形圆钢管节点进行支管平面外弯矩作用下的试验研究。考察了支管、主管分别填混凝土2种情况下节点的破坏模式和应力分布,并分析了钢管内混凝土对节点平面外抗弯刚度及承载力的影响。试验中支管填混凝土节点出现了主管塑性、支管局部屈曲和支管受拉侧焊缝或热影响区管壁开裂的破坏模式,主管填混凝土节点则发生了支管局部屈曲及支管受拉侧焊缝开裂破坏。主管填混凝土节点与支管填混凝土节点相比,由于主管内填混凝土对于主管管壁的局部变形起到明显的约束作用,明显提高了主管的径向刚度,增大了节点的平面外抗弯刚度。实测节点承载力与欧洲规范计算的空钢管节点理论承载力比较表明,主管内填混凝土能极大提高节点平面外受弯承载力,最大可提高132%;支管内填混凝土可使节点平面外受弯承载力最大提高60%。