考虑倒角系数的T型铸钢节点轴向承载力非线性分析

铸钢节点造型美观、受力性能合理,在建筑结构中得到了越来越广泛的应用.与传统焊接管节点相比,铸钢节点用圆形倒角取代了相贯线处的焊缝,应力集中小,承载力高.本文针对T型铸钢节点,通过So lidw orks软件建立三维模型,采用通用有限元软件AN SY S进行非线性分析.结合有限元计算结果,对T型铸钢节点的轴向承载力进行了参数分析,给出了T型铸钢节点在支管受轴力作用下的极限承载力公式.该公式确立了极限承载力与铸钢节点几何参数之间的关系.在焊接管节点几何参数的基础上,铸钢节点增加了由C.D.Edw ards首次提出的倒角系数.本文重点讨论了该系数对铸钢节点承载力的影响.     

平面外弯矩作用下的T形铸钢节点承载力非线性分析

铸钢节点造型美观、受力性能合理,在建筑结构当中得到了越来越广泛的应用.与传统焊接管节点相比,铸钢节点用圆形倒角取代了相贯线处的焊缝,应力集中小,承载力高.针对T形铸钢节点,通过Solidworks软件建立三维模型,采用通用有限元软件Ansys进行非线性分析.结合有限元计算结果,对T形铸钢节点在平面外弯矩作用下的承载力进行了参数分析,给出了T形铸钢节点在支管受平面外弯矩作用下的极限承载力公式.公式确立了极限承载力与铸钢节点几何参数之间的联系.在焊接管节点几何参数的基础上,铸钢节点增加了由C.D.Edwards首次提出的倒角系数ρ并重点讨论了该系数对铸钢节点承载力的影响.     

大跨复杂斜撑钢结构铸钢节点力学性能分析

大跨斜撑钢结构节点受力复杂且施工难度较大,其节点通常采用整体式铸钢节点。根据实际工程建立铸钢节点精细化有限元分析模型,研究结构施工过程中铸钢节点的力学性能和安全性能。选取四个关键施工阶段,研究施工过程中铸钢节点关键部位应力及位移,同时分析壁厚和倒角半径对铸钢节点受力性能的影响。结果表明:施工过程中,由于倒角部位截面刚度突变,部分出现应力集中现象,其余部位应力较小;施工过程中铸钢节点圆柱由于截面刚度较小,其端部变形较大。研究成果可为大跨复杂斜撑钢结构铸钢节点设计及施工提供参考。     

主管夹层灌混凝土的K型搭接节点滞回耗能分析

为了探究主管夹层灌混凝土加强措施对圆钢管K型搭接节点滞回性能的影响,对1个主管夹层灌混凝土的K型搭接节点试件和1个未加强K型搭接节点试件进行低周往复拟静力试验,得到了节点的滞回曲线、骨架曲线、承载力、延性系数和能量耗散系数等抗震性能指标,试验结果表明:主管夹层灌混凝土,可有效提高节点的承载力、强度储备和耗能能力,但对节点的延性影响不大。利用ANSYS软件建立节点数值分析模型,模拟结果与试验结果吻合较好,并针对内套管钢材等级、主管钢材等级及混凝土等级开展有限元参数分析。分析结果表明:内套管钢材等级的增加不利于节点的滞回耗能,当采用Q235B时节点的滞回性能最好;当主管钢材等级为Q345B时,节点的各项性能均表现良好,滞回耗能能力最优;而混凝土等级对节点滞回性能影响较小,分析结果可为该类节点的优化设计提供一些参考。     

板管连接方管节点滞回性能的有限元分析

采用有限元软件ANSYS对T型纵向板管连接的方管节点进行了弹塑性大挠度分析,研究了此种节点在往复荷载作用下的滞回性能,通过分析节点的滞回曲线、骨架曲线、滞回环面积曲线和能量耗散系数曲线,得出了纵向板管节点的耗能能力随各参数的变化规律。     

波折腹板钢梁柱半刚性外伸端板连接节点滞回性能研究

为研究波折腹板钢梁柱半刚性外伸端板连接节点的滞回性能,采用ANSYS有限元软件,对半刚性外伸端板连接节点施加循环荷载,得到其弯矩-转角滞回曲线,分析节点的受力特性和延性系数;分别调整梁腹板高度和厚度,分析其对弯矩-转角滞回曲线的影响。结果表明:随着荷载的增大,残余变形的累加,节点承载力和刚度逐渐降低,弯矩-转角滞回曲线由线性特征转变为非线性特征;梁腹板高度和梁腹板厚度对节点的延性系数和滞回性能影响显著。     

内置加劲板加固T型方钢管节点试验研究

为了研究内置加劲板加固对T型方钢管节点的影响,对1个未加劲节点和1个内置加劲板加固节点进行了拟静力滞回性能试验,结果表明:加固后的节点滞回曲线更加饱满;节点的极限承载力、延性系数比未加固节点明显增加,具有更好的抗震性能。     

装配式高强钢筋混凝土框架节点滞回性能试验研究

为研究装配式带钢连接件混凝土柱-预埋工字钢混凝土梁连接节点的滞回性能,设计2个装配式高强钢筋混凝土框架节点和1个现浇高强钢筋混凝土框架节点,进行低周往复加载试验,对比分析其滞回性能、刚度退化、骨架曲线、承载力退化和耗能能力等。结果表明:与现浇高强钢筋混凝土框架节点试件相比,带钢连接件混凝土柱-预埋工字钢混凝土梁连接节点试件的滞回曲线更为饱满,刚度退化得到有效减缓,承载力降低系数增加,各主要阶段的等效黏滞阻尼系数和总等效黏滞阻尼系数增加,耗能能力得到提高,承载能力和变形能力也得到提高;预制柱中采用带水平连接板的方钢管连接件在改善装配式混凝土框架节点滞回性能方面效果更佳。     

杭州湾观光塔铸钢节点疲劳性能试验研究

杭州湾跨海大桥观光塔处于近海,结构受到海洋波浪荷载的作用,需对塔中2个铸钢节点的疲劳性能进行试验研究。通过对塔中的2个铸钢上节点模型(缩尺比例为1∶4)的静载试验和抗弯疲劳试验,研究了GS-20Mn5V的铸钢节点的疲劳性能。试件在3种循环荷载作用下的滞回曲线的变化和应变随着循环次数的增加而降低的规律表明,GS-20Mn5V铸钢属于应力强化材料。分析试件在不同应力幅作用下的疲劳寿命变化,得到了GS-20Mn5V铸钢节点的疲劳极限及S-N曲线。研究结果表明,观光塔中的铸钢节点在波浪荷载作用下能够保证结构安全。     

K型间隙方管节点滞回性能的有限元分析

为了研究直接焊接K型间隙方钢管节点滞回性能,采用有限元分析软件ANSYS对典型K型间隙方管节点进行了轴向往复荷载作用下弹塑性、大变形有限元分析。对不同几何参数下节点滞回性能进行了分析,得出了用以评价节点抗震性能的主要指标（骨架曲线、能量耗散系数）,作为近一步研究方管桁架抗震性能的基础。     

Hysteretic behaviour of square tubular T-joints with chord reinforcement under axial cyclic loading

The stiffness of hollow section tubular joints is weak in the chord radial direction, and thus failure frequently occurs at the weld toe in the form of brittle fracture caused by crack propagation due to cyclic loading. To avoid such brittle failure, the chord at the intersection can be reinforced by increasing the chord thickness. With the chord reinforced, the failure position can be transferred to the chord intersection, and hence the cracking along the weld toe is prevented. To verify the efficiency of the proposed reinforcing method, both experimental test and finite element analysis are carried out on reinforced and un-reinforced square tubular T-joints subjected to quasi-static cyclic loads. The hysteretic curves, ductility ratio, energy dissipation and failure mode of the two full-scale specimens are studied experimentally, and it is found that the hysteretic curves of both specimens are plump, which show the T-joints can absorb much energy when they are subjected to seismic action. However, the enclosed area of the hysteretic curves of the reinforced T-joint is larger than that of the un-reinforced specimen because the chord reinforcement can prevent the fracture failure as well as improving the bearing capacity. The failure performance of the reinforced and un-reinforced specimens also show that a T-joint with chord reinforcement is more advantageous in resisting seismic action. Finally, the effect of the reinforced chord length and thickness on the hysteretic behaviour of square tubular T-joints is also investigated from a parametric study.     

Hysteretic performance of circular hollow section tubular joints with collar-plate reinforcement

Welded tubular joints have a weak stiffness in the chord radial direction due to the hollow section, and failure frequently occurs mostly on the chord surface along the weld toe. In the past, collar-plate has been proven to be effective in improving the stiffness and thus increasing the load carrying capacity of a tubular joint. This paper reports the results of a further study on investigating the effect of collar-plate reinforcement on the hysteretic behavior of a welded tubular joint. Overall, a total of 4 tubular T-joints with collar-plate reinforcement together with 4 corresponding un-reinforced specimens are studied experimentally. In the experimental tests, quasi-static axial cyclic loading is applied to these specimens. The hysteretic performance of the reinforced and un-reinforced T-joint specimens is then evaluated from the hysteretic curves, ductility and the energy dissipation ratio etc. Based on the experimental results, it is found that the T-joint specimens with collar-plate reinforcement can dissipate more energy before failure when they are subjected to cyclic loading compared to the un-reinforced ones, and thus they have a more ductile characteristic. Such ductility is attributed to the improved deformed capacity as well as the increased load carrying capacity of the reinforced T-joints.     

Hysteretic performance of circular hollow section tubular joints with collar-plate reinforcement

Welded tubular joints have a weak stiffness in the chord radial direction due to the hollow section, and failure frequently occurs mostly on the chord surface along the weld toe. In the past, collar-plate has been proven to be effective in improving the stiffness and thus increasing the load carrying capacity of a tubular joint. This paper reports the results of a further study on investigating the effect of collar-plate reinforcement on the hysteretic behavior of a welded tubular joint. Overall, a total of 4 tubular T-joints with collar-plate reinforcement together with 4 corresponding un-reinforced specimens are studied experimentally. In the experimental tests, quasi-static axial cyclic loading is applied to these specimens. The hysteretic performance of the reinforced and un-reinforced T-joint specimens is then evaluated from the hysteretic curves, ductility and the energy dissipation ratio etc. Based on the experimental results, it is found that the T-joint specimens with collar-plate reinforcement can dissipate more energy before failure when they are subjected to cyclic loading compared to the un-reinforced ones, and thus they have a more ductile characteristic. Such ductility is attributed to the improved deformed capacity as well as the increased load carrying capacity of the reinforced T-joints.     

方钢管混凝土柱-钢梁外隔板式节点静力和滞回性能分析

采用有限元软件ANSYS对方钢管混凝土柱-钢梁节点进行了非线性静力分析和滞回分析,讨论外隔板式节点翼缘斜率对节点的应力分布规律、承载力、延性和滞回性能的影响.分析表明,外隔板式节点具有很好的刚度和延性,节点滞回环饱满,耗能能力强,当梁端翼缘斜率不小于1/4时,可获得更好的受力性能.梁柱连接处柱脚附近应力集中现象严重,因此梁柱连接的焊缝质量要有充分保证.     

Y形直接焊接矩形钢管节点滞回性能试验研究

对钢管结构中常用的Y形矩形钢管节点进行了试验研究。通过对支管施加轴向往复荷载,共对10个直接焊接Y形矩形管节点进行拟静力试验。为研究钢管加工及节点焊接过程中产生的残余应力对节点性能的影响,对其中2个节点进行了去应力退火处理。通过分析节点的承载力、延性比和能量耗散系数,对此种节点的滞回性能进行了深入研究。试验表明：在支管承受轴向往复荷载作用时,总是在支弦管连接焊缝外边缘沿支管侧壁方向切断弦管上壁面,从而导致节点性能的劣化。在弦管上壁面拉裂之前节点耗能性能良好,且退火节点在弦管上壁面拉裂之后仍然有较大的耗能潜力。节点的滞回性能较好,这为在抗震区推广使用管结构提供了有力支持。     

方钢管混凝土柱-钢梁外隔板式节点静力和滞回性能分析

采用有限元软件ANSYS对方钢管混凝土柱—钢梁节点进行了非线性静力分析和滞回分析,讨论外隔板式节点翼缘斜率对节点的应力分布规律、承载力、延性和滞回性能的影响。分析表明,外隔板式节点具有很好的刚度和延性,节点滞回环饱满,耗能能力强,当梁端翼缘斜率不小于1/4时,可获得更好的受力性能。梁柱连接处柱脚附近应力集中现象严重,因此梁柱连接的焊缝质量要有充分保证。     

Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tubular steel T-joints

A method for strengthening damaged tubular steel T-joints under axial compression by wrapping them with carbon fiber-reinforced polymer (CFRP) sheets was proposed and evaluated. The influence of the CFRP strengthening on the failure mode and load capacity of T-joints with different degrees of damage was investigated using experiments and finite element analyses. Five T-joints were physically tested: one bare joint to obtain the peak load and corresponding displacement (D_1m), two reinforced joints to provide a reference, and two pre-damaged then retrofitted joints to serve as the primary research objects. The ratio of the pre-loaded specimen chord displacement to the value of D_1m was considered to be the degree of damage of the two retrofitted joints, and was set to 0.80 and 1.20. The results demonstrate that the maximum capacity of the retrofitted specimen was increased by 0.83%–15.06% over the corresponding unreinforced specimens. However, the capacity of the retrofitted specimen was 2.51%–22.77% lesser compared with that of the directly reinforced specimens. Next, 111 numerical analysis models (0.63≤b≤0.76, 9.70≤g≤16.92) were established to parametrically evaluate the effects of different geometric and strengthening parameters on the load capacity of strengthened tubular T-joints under different degrees of damage. The numerical analysis results revealed that the development of equivalent plastic strain at the selected measuring points was moderated by strengthening with CFRP wrapping, and indicated the optimal CFRP strengthening thickness and wrapping orientation according to tubular T-joint parameters. Finally, reasonable equations for calculating the load capacity of CFRP-strengthened joints were proposed and demonstrated to provide accurate results. The findings of this study can be used to inform improved CFRP strengthening of damaged tubular steel structures.     

空间隔板焊接X形圆钢管相贯节点受力性能试验研究

对3个足尺空间隔板焊接X形圆钢管相贯节点分别进行了轴力作用下的单调加载试验和往复加载试验,得到了节点的破坏模式,并对节点的受力性能包括静力弹性刚度、承载力、延性和滞回性能等进行分析。验证了该种空间隔板焊接节点的构造措施合理,节点的承载能力相对设计工况有两倍以上的安全储备,节点受力安全可靠。运用ABAQUS软件建立有限元分析模型,并与试验结果对比,验证了有限元模型的适用性,并对节点进行设计工况下的内力校核,参数分析结果表明,管径厚比、相贯角度、椭圆连接板厚度及平面外角度对空间隔板焊接节点性能影响较大,节点刚度和承载力随着支管径厚比和平面外角度的增大而降低,随着相贯角度和椭圆连接板厚度的增大而提高。综合试验和有限元分析结果,节点设计要确保支管设计内力不大于节点承载力,增大椭圆板厚度以及补焊椭圆板隐藏焊缝对节点的受力性能改善较好;当设计该类较小相贯角度（小于20°）的节点时,需按节点承载力进行设计,同时考虑轴向刚度对节点受力性能的影响。     

重庆渝北体育馆铸钢节点受力性能分析

重庆渝北体育馆屋盖结构设计中采用大型铸钢节点,该铸钢节点的安全直接关系到整个结构的安全。为深入了解该铸钢节点的受力性能并确保结构在设计荷载下的安全性,根据设计要求对该铸钢节点进行精细有限元分析,从而了解该铸钢节点在设计荷载下的受力特征以及弹塑性极限承载性能。分析表明,该节点圆弧过渡区域存在应力集中现象。着重研究不同角度杆件交汇处的过渡圆弧半径对圆弧过渡区域应力集中的影响。分析结果表明:当铸钢节点处于弹性工作阶段时,过渡圆弧半径取临界半径值,能够显著降低圆弧过渡区域的应力集中,延缓节点屈服的进程。增大过渡圆弧半径时,当铸钢节点处于弹性工作阶段,小角度交汇处应力集中降低程度较大;当铸钢节点处于屈服阶段,大角度交汇处应力集中降低程度较大。