国家体育场焊接方管桁架双弦杆KK型节点试验研究

正在建设的国家体育场两两斜交的主桁架构成了许多双弦杆焊接方管KK型节点,该节点连接焊缝密集,构造极其复杂。本文对这种在管结构中较为独特的节点进行了1∶4的缩尺模型承载力试验研究,详细介绍了节点的试验方法和结果,讨论了节点的受力性能、破坏模式以及节点内部加劲肋的作用。研究表明该节点的构造措施较完善可靠,节点具有较高的承载力。节点的薄弱部位处在受压腹杆端部,发生局部屈曲。弦杆内部纵横向加劲肋的设置有效地增强了节点强度和刚度。腹杆端部的局部放大改善了腹杆向弦杆的传力,降低了应力集中。     

T形节点多尺度模型的有限元分析

由于现有的国内外规范对于方支管-H型钢弦杆T形节点中弦杆翼缘屈曲考虑欠缺,从而引起了相关设计人士的重视。基于阿布扎比国际机场中拱桁架的多尺度模型,对桁架中方支管-H型钢弦杆T形节点的弦杆屈曲进行了有限元分析。研究表明:弦杆上远离与方管焊接处一侧的翼缘趋向于受压应力作用,更容易发生屈曲。当压应力较大时,该侧翼缘的屈曲呈现波浪型。对拱桁架中的方支管-H型钢弦杆T形节点的弦杆局部屈曲进行设计时,根据弦杆上远离与方管交接处一侧的翼缘的屈曲形态来布置加劲肋是比较合理的选择。     

阿布扎比国际机场航站楼拱桁架中T形节点设计

采用ANSYS软件对阿布扎比国际机场航站楼拱桁架中的方支管-H型钢弦杆的T形节点进行分析。分析结果表明:随着弦杆轴向压力的增大,节点承载力有一定的降低。另外,弦杆与腹杆的不同受力情况,决定了弦杆翼缘的不同屈曲形态。列出典型的3种翼缘变形状态,并给出不同屈曲形态的受力分布区域,为设计提供了方案选择的便利。     

国家体育场桁架柱内柱多腹杆焊接节点性能研究

对国家体育场钢结构桁架柱的节点进行了比例为1∶5的缩尺模型试验研究和有限元分析。该节点为主桁架梁与桁架柱的连接节点,由1根菱形内柱与11根箱形截面腹杆形成的复杂空间管节点,并且节点内布置了许多加劲肋。论文介绍了节点的试验方法,描述了整个加载过程中节点行为和最后的破坏模式。从节点受力性质、构造、几何尺寸等角度,讨论了节点的破坏机理。研究表明节点的薄弱环节出现在受压腹杆,发生局部屈曲。弦杆内设置加劲肋是防止弦杆板件塑性破坏和局部屈曲的有效构造措施。论文提出了实际结构中该节点设计和制作时应采取的措施。     

KT型相贯节点承载力有限元及设计方法分析

对KT型圆钢管空间相贯节点的极限承载力进行非线性有限元分析,揭示KT型相贯节点的受力性能。结果表明：在支杆轴力大小不同的情况下,随着支杆与弦杆直径比角、腹杆与弦杆直径比屉、支杆与弦杆厚度比τ1、腹杆与弦杆厚度比τ2和弦杆径厚比γ的变化,节点发生弦杆局部屈曲模式、腹杆轴向屈曲破坏和支杆强度破坏3种破坏模式;有焊缝的加强作用,节点承载力有所提高;分析支杆与腹杆轴力不同比值情况下的节点承载力,提出KT型节点承载力简化设计公式。     

设置加劲肋圆钢管T型相贯节点面内抗弯承载力试验研究及模拟分析

为提高相贯节点的承载力和疲劳寿命,在节点区域设置加劲肋,开展设置加劲肋T型圆钢管相贯节点面内抗弯承载力的试验研究,探讨了设置加劲肋T型相贯节点的破坏模式、应变发展规律和抗弯承载力特性;试验中主管受压侧加劲肋附近应变发展较快,当节点荷载临近极限承载力时,节点主管受压侧加劲肋附近发生明显凹陷的局部屈曲,同时加劲肋发生面外弯曲失稳;设置加劲肋节点面内抗弯承载力比无加劲肋节点承载力明显提高,说明设置加劲肋后有效提高了节点抵抗变形的能力,增加了节点的刚度和强度,使节点承载力有大幅度的提升。同时,开展相贯节点的非线性有限元模拟,分析得到节点的失效模式、承载力与试验均吻合较好。基于非线性有限元模拟,考察加劲肋布置方式对抗弯承载力的影响,提出了合理的加劲肋布置方式。     

方钢管柱-H形钢梁槽钢节点受力性能研究

为研究方钢管柱-H形钢梁槽钢节点的静力性能,对5个节点试件进行了单调加载静力试验。试件为边柱节点,试件参数为槽钢类型、槽钢尺寸以及管内加劲肋。详细考察试验全过程和试件破坏形态,分析节点的转动刚度、承载能力、应力-应变关系等。采用有限元软件ABAQUS对节点进行有限元分析,将有限元得到的M-θ曲线与试验结果进行对比。研究结果表明:试件破坏时,破坏主要发生在槽钢上,主要表现为螺栓孔撕裂、槽钢受拉侧腹板鼓曲、受压侧翼缘屈曲;槽钢翼缘与钢管柱壁刚度比较小时,槽钢翼缘会出现明显鼓曲;槽钢翼缘与钢管柱壁刚度比较大时,钢管壁受压区会出现较明显局部屈曲,槽钢腹板越厚,节点承载力越高;槽钢节点有较好的变形能力与抗弯承载能力,为半刚性节点。     

国家体育场桁架柱外柱节点设计研究

国家体育场桁架柱外柱节点的几何关系复杂,存在T型、K型及KT型等多种腹杆形式,腹杆侧壁与外柱壁板斜交,还存在与立面次结构相交的情况。焊接薄壁箱形构件相贯节点的刚度差,承载力低。本文通过在外柱内设置横向加劲肋与局部纵肋等构造做法,可以有效提高节点刚度与承载力。对于有次结构的外柱节点,次结构的上、下壁板不能全部贯通,在保证腹杆与外柱传力可靠的前提下,在外柱节点区设置传力三角区。对于K型腹杆节点,翼缘较厚的腹杆贯通;对于KT型腹杆节点,中间腹杆贯通。通过合理设计拼接焊缝位置、采用整板切割等方式,可以有效减少焊缝数量,避免焊缝重叠。采用有限元法分析外柱节点的受力形态,并根据“最大平均应力”的原则确定节点域板件的厚度,实现“强节点”的设计理念,保证节点的可靠性与经济性。     

节点域斜加劲肋设计计算方法

我国现行钢结构设计规范与规程对梁柱节点域的抗剪能力提出了具体的要求,并指出当节点域抗剪能力不足时可设置斜向加劲肋。但是却没有给出所设置的斜加劲肋的计算办法。采用有限单元法对考虑了斜肋板宽厚比、腹板宽厚比、节点域高宽比、柱翼缘宽厚比等多种影响因素的节点域模型进行了屈曲后强度计算,分析了各种不同情况下的节点域的变形及应力分布,提出了有斜加劲肋的节点域的等效计算模型及计算公式,并推导了门式刚架节点域斜加劲肋的设计计算公式。     

高铁虹桥站钢桁架-钢管混凝土柱节点性能试验研究

最近建设完成的京沪高速铁路上海虹桥站结构中,有一种钢桁架-钢管混凝土柱焊缝连接的新型节点,该节点构造和受力性能极其复杂。本文对该节点进行了1∶4缩尺模型承载力试验研究,介绍了如何实施对该复杂节点加载的试验方法,讨论了节点的受力性能、薄弱环节和破坏模式。试验表明该节点构造设计有效,具有足够的承载力,可达到设计荷载的3倍,并具有良好的塑性变形能力。但是,节点也显示出薄弱坏节,表现为在钢桁架受拉斜腹杆翼缘与节点环板竖向加劲肋的焊接部位出现开裂现象。建议适当增大受拉斜腹杆端部的翼缘弯折曲率半径,平缓腹杆向竖向加劲肋的传力,可使节点性能得到进一步完善。     

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%。     

加劲肋对钢管相贯节点力学性能的影响

加劲肋可以提高钢管相贯节点的承载力及刚度,进而提高节点可靠性和结构整体稳定性.其中,加劲肋的平面尺寸、厚度、形状以及加劲肋是否贯穿钢管等对节点的刚度、承载力及延性有很大影响.以一个钢管相贯节点足尺试验为基础,通过一系列扩展的有限元模型来分析加劲肋厚与管厚比、加劲肋尺寸与管径比和加劲肋是否贯穿钢管等因素对节点承载力、屈服前后刚度以及延性的影响.研究结果表明,加劲肋可以显著提高节点承载力和刚度.对于仅焊于钢管外的加劲肋,合理的厚度比(加劲肋厚度与管壁厚度之比)为α=0.5 ～1.0;对于贯穿钢管的加劲肋,合理的厚度比为α=0.5 ～0.8;加劲肋边长与管径之比β的合理取值为0.6～1.     

Local buckling of braces in tubular K-joints

The local buckling of compression braces is one of the recognized failure modes yet to be studied in three-member truss connections of circular tubular members. A series of tests was performed to examine the brace local buckling behavior. The test results demonstrate that the brace local buckling is influenced not only by the wall thickness of the braces but also by the stiffness of the joints. Simple prediction equations for both the resistance and the deformation capacity of the joints failing in this mode are presented on the basis of these test results. It is shown that joint deformation can have beneficial effects on the overall ductility of trusses, when diameter-to-thickness ratios of braces are limited within the range of this test.     

开孔钢板加劲的矩形钢管钢纤维高强混凝土柱轴压试验研究

为探明加劲肋类型、开孔钢板（PBL）开孔间距、钢纤维体积掺量、混凝土强度等级等对矩形钢管钢纤维高强混凝土（SFRHC）柱轴压破坏模式的影响规律,对10根柱进行了轴压性能试验,得到了其荷载-压缩变形曲线、位移延性系数、耗能指标和破坏模式。研究结果表明：与PBL加劲试件相比,钢板加劲试件和未加劲试件的位移延性系数分别降低11.9%和10.4%,耗能指标分别降低8.3%和5.6%, PBL加劲肋能有效加强钢管与核心混凝土的组合作用。掺入体积率为0.8%钢纤维的PBL加劲试件,其位移延性系数和耗能指标分别提高12.5%和42.3%,钢纤维体积率为0.8%~1.2%时,试件位移延性系数和耗能指标明显提高。加劲SFRHC柱为肋间管壁局部外鼓破坏,PBL加劲柱的破坏位置均位于PBL开孔处,未加劲SFRHC柱为管壁外鼓破坏,对应钢板屈曲处核心混凝土表现为压碎破坏,钢纤维被整体拔出;加劲SFRHC柱沿高度方向破坏位置明显下移,钢板加劲肋和PBL加劲肋均能有效分担轴向荷载。     

Strength of tubular welded joints of roof trusses in Shanghai Qizhong Tennis Center

Static strength of multi-planar welded joints with seven brace members and one chord member made of circular hollow sections is investigated in the paper, based on the engineering practice of moveable roof trusses of Shanghai Qizhong Tennis Center. Firstly, comparative experiments were carried out on two model joints with a scale of 1:3. One joint was not reinforced, whereas the other was reinforced with ring stiffeners inside the chord member. Failure mode, stress distribution, plastic-zone development and ultimate load capacity of the joints were investigated, and effects of the ring stiffeners on the joint behavior were observed through the experiments. Secondly, finite element analysis of both the tested model joints was performed. The calculation results are in a good agreement with the experimental results, which indicated that the numerical analysis was quite effective. Finally, the strategy for enhancing strength of the complicated joint is discussed. Parameters study on the constructional details of ring stiffeners was carried out using FE method. The present research shows the multi-planar circular hollow section joint with high ratio of diameter to thickness of the chord and multiple braces is liable to chord plasticity under axial tension and compression on the braces. For the design of the joint, it is suggested that the ring stiffeners are installed insider the chord to meet needs of enough stiffness and strength. Both position and number of the stiffeners should be carefully determined based on the axial forces on the braces and their diameters. The stiffener thickness should not be less than the chord thickness, and the diameter of the hole at the center of the stiffener should not be greater than half of the chord diameter.     

Beulverhalten gedrückter Kastenprofile mit verschiedenen Steifen

Local buckling behaviors of box section with various stiffeners subjected to compressive load. An analytical procedure for the elastic local buckling problems of box‐section with open, closed and L‐type stiffeners by the extended matrix method is presented. An exact solution can be obtained by treating the compressive box‐section with stiffeners as the branching panels in the transfer matrix method. The results are given as two local buckling behaviors. The first local buckling behavior is the local buckling shape to become a joint at the position of the each stiffener, and the second local buckling behavior is the local buckling shape of individual plate to compose box‐section.     

Experimental research on mechanical behavior of concrete-filled thin-walled stiffened square steel tubular short column under axial load

为研究带肋薄壁方钢管混凝土轴压短柱的受力性能,以钢管宽厚比、加劲肋宽度和加劲肋个数为参数,对26个薄壁方钢管混凝土短柱进行了试验研究。研究结果表明：对于无肋试件,在达到承载力以前管壁已经发生鼓曲,且试件宽厚比越大,鼓曲越早发生,鼓曲部位的钢管截面越早退出工作,没有发挥出钢管混凝土的优势。设置加劲肋后薄壁方钢管混凝土短柱的受力性能得到明显改善,钢管壁的局部鼓曲得以延缓,材料强度得到了充分利用,试件承载力提高。当试件宽厚比为60、80时,加劲肋宽度对试件承载力影响最明显,加劲肋宽度越大,承载力越高,增加加劲肋个数对试件承载力影响不大;而当试件宽厚比为100时,设置单个加劲肋已不能满足对管壁局部屈曲的抗弯刚度要求,必须增加加劲肋的个数以增加约束钢管变形的支撑点,减小管壁局部屈曲的波长,提高试件局部屈曲的临界荷载。同时利用ABAQUS有限元计算软件对薄壁带肋方钢管混凝土轴压短柱的受力全过程进行了模拟,并将试验结果与有限元模拟结果进行了对比,两者吻合良好,为下一步分析奠定基础。     

Experimental and Numerical Study on Complex Multi-planar Welded Tubular Joints in Umbrella-Type Space Trusses with Long Overhangs

A test rig with multi-functional purposes was specifically designed and manufactured to study the behavior of multi-planar welded tubular joints subjected to multi-planar concurrent axial loading. An experimental investigation was conducted on full-scale welded tubular joints with each consisting of one chord and eight braces under monotonic loading conditions. Two pairs or four representative specimens (two specimens for each joint type) were tested, in which each pair was reinforced with two kinds of different internal stiffeners at the intersections between the chords using welded rectangular hollow steel sections (RHSSs) and the braces using rolled circular hollow steel sections (CHSSs) and welded RHSSs. The effects of different internal stiffeners at the chord–brace intersection on the load capacity of joints under concurrent multi-planar axial compression/tension are discussed. The test results of joint strengths, failure modes, and load–stress curves are presented. Finite element analyses were performed to verify the experimental results. The study results show that the two different joint types with the internal stiffeners at the chord–brace intersection under axial compression/tension significantly increase the corresponding ultimate strength to far exceed the usual design strength. The load carrying capacity of welded tubular joints decreases with a higher degree of the manufacturing imperfection in individual braces at the tubular joints. Furthermore, the interaction effect of the concurrent axial loading applied at the welded tubular joint on member stress is apparent.     

G550高强冷弯薄壁Z形钢受弯构件承载力试验与直接强度法研究

为了研究高强冷弯薄壁型钢构件的受弯性能和完善直接强度法,对卷边形式为斜卷边、直卷边和复杂卷边的12个G550高强冷弯薄壁Z形钢受弯试件进行了静力试验。试验结果表明,卷边形式对试件屈曲模式和受弯承载力有显著影响,试件发生了局部与畸变相关屈曲或畸变屈曲,直卷边试件的承载力高于斜卷边试件的承载力,复杂Ⅱ型卷边试件的承载力高于复杂Ⅰ型卷边试件的承载力。根据试验结果并结合现有国外直接强度法公式,回归出G550高强冷弯薄壁Z形钢受弯构件发生局部与畸变相关屈曲变形时的承载力直接强度法修正公式,当此类构件发生畸变屈曲时,无需再修正现有直接强度法公式。建立有限元模型对试验进行了分析,分析结果与试验结果吻合良好。在此基础上,利用大量有限元分析结果验证了直接强度法修正公式比现有直接强度法公式对此类构件的承载力的预测更为安全可靠。     

钢板剪力墙低周反复荷载试验研究

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