超大承载力端板连接节点试验研究

在大跨或重载钢结构中,当梁柱之间需要采用螺栓连接时,如果普通构造的端板连接节点和大承载力端板连接节点不能满足承载力要求,则需要采用受拉区布置12颗或16颗螺栓的超大承载力端板连接节点。为研究该类型节点受力性能,进行4个超大承载力端板连接节点足尺试件的单调加载试验,得到各节点试件的弯矩-转角曲线,分析不同螺栓直径、端板厚度和螺栓布置形式下各节点的抗弯承载力、转动刚度和受拉区螺栓拉应变增量分布的特点。结果表明,在试验试件构造条件下超大承载力端板连接节点的弯曲失效模式为端板屈服后螺栓失效,端板厚度对节点承载力影响明显;各螺栓的拉应变增量分布不均匀,角部螺栓对节点抗弯承载力影响较小,建议在设计中移除或仅按抗剪螺栓考虑;建议节点域屈服承载力仍按照现行规范计算,该类节点的等效受拉螺栓数量取为7。     

超大承载力端板连接节点抗拉性能及设计方法

超大承载力端板连接节点是一种新型梁柱节点形式,可以应用于大跨或重载钢框架中。在抗震区框架中梁柱节点除承担弯矩之外还可能承担一定的拉力,因此有必要对超大承载力端板连接节点的抗拉性能进行研究。对4个采用不同端板厚度、螺栓直径或螺栓布置形式的超大承载力端板连接节点足尺试件进行了轴拉荷载下的试验研究,记录并分析了各螺栓轴向应变增量分布情况;建立了24个超大承载力端板连接节点的有限元模型并进一步分析了该节点的抗拉性能。基于试验研究和有限元分析的结果得出:在轴拉荷载下端板外伸段靠近梁翼缘中部的螺栓为最不利螺栓,而移除角部螺栓对节点的抗拉性能没有不利影响;提出了该节点受拉时等效受拉螺栓数量的建议计算式,并给出了节点抗拉承载力的设计方法。     

外伸端板高强度螺栓抗拉连接设计方法研究

通过建立系列有限元分析模型研究了外伸端板高强度螺栓抗拉连接的力学性能,分析中考虑了不同端板厚度和螺栓直径变化对连接节点受力性能的影响。研究结果表明,高强度螺栓总拉力应由外加荷载引起的螺栓拉力和端板弯曲变形产生的撬力组成。通过分析拟合得到由外加荷载产生的螺栓拉力和螺栓撬力的分布模型和计算公式,并分别给出摩擦型和承压型两种类型的高强度螺栓考虑撬力影响抗拉连接承载力计算公式。     

外伸端板高强螺栓受拉连接的计算分析

针对国内外关于外伸端板高强螺栓受拉连接的受力分析方法,研究端板刚性、弹塑性、塑性和T形件4种力学计算模型。端板刚性分析中将端板按无弯曲变形的刚性体考虑;弹塑性分析中假定受拉翼缘两侧的两排螺栓承担相同拉力,并考虑端板的部分塑性变形;塑性分析中每个螺栓的受力依赖于其本身的承载力,各排螺栓随拉力的增大依次达到屈服;T形件模型考虑端板的弹塑性变形,将受拉翼缘和螺栓简化为T形连接件。通过例题研究4种计算模型下高强螺栓受拉连接的计算方法,可为工程设计提供参考。     

负弯矩作用下钢管混凝土组合框架端板连接节点的抗弯承载力计算方法

为了获悉负弯矩作用下钢管混凝土组合框架端板连接节点的抗弯承载力,给出组合节点的失效模式,建立对称荷载和非对称荷载作用下组合节点的力学模型,详细考虑柱截面类型、端板类型、荷载类型、楼板组合作用的影响。基于节点失效模式,分别提出钢筋抗拉承载力、螺栓抗拉承载力、连接抗压承载力等组件承载力的简化计算方法。根据力学平衡原理和力学模型,利用组件法,确定组合节点受弯中和轴位置,分别提出平齐端板连接和外伸端板连接钢管混凝土组合节点在负弯矩作用下的承载力计算公式。用试验结果验证了所提组合节点抗弯承载力简化计算方法的正确性,研究成果可为建立半刚性钢管混凝土组合框架设计理论提供科学依据。     

带填板的端板连接梁拼接节点抗弯性能有限元分析

目前装配式钢梁连接常采用高强螺栓端板连接形式，构件在工厂制作完成，加工精度高；构件运抵施工现场采用高强螺栓完成拼接，安装快捷方便；但在连接端板之间经常存在对接缝隙，工程中常采用填板弥补空隙。但目前相关规范中对于填板的厚度并无规定。为研究填板对于端板连接梁梁拼接节点抗弯刚度及抗弯承载力的影响，采用有限元软件ABAQUS建立了含有填板的端板连接节点实体单元模型，设置了结构各组件间复杂的接触关系，考虑了端板厚度及填板厚度的影响，研究了螺栓杆的拉力传递、中和轴位置的变化、填板的受力情况及端板受拉区的极限受力状态等工作机理。分析结果表明：当钢梁为H400×200×8×13,端板为-400×200×t_p1(t_p1=12～24 mm)时，随着填板厚度的增加，节点的初始抗弯刚度减小，当填板厚度在15 mm以内时，对节点抗弯承载力无明显影响。     

门式刚架轻型房屋钢结构端板连接的有限元与试验分析

结合门式刚架轻型房屋钢结构中普遍应用的端板连接方式 ,本文对梁柱节点和梁拼接节点进行了试验和有限元分析 ,对外伸式端板连接的承载力和转动刚度特性进行了研究 ,讨论了我国现行规范关于外伸式端板连接的设计方法中存在的问题 ,同时给出了改进建议 ,特别是提出了在建立钢结构节点刚度分类标准方面应该注意的问题。根据比较分析的结果 ,本文还提出了一种新的外伸式端板连接螺栓拉力分布模型及相应的设计方法 ,试验证明 ,该方法在保证安全可靠的前提下 ,能够更好地符合螺栓端板连接的实际受力状态 ,发挥螺栓和端板的承载能力     

超大承载力端板连接节点螺栓施拧顺序及预拉力松弛研究

超大承载力端板连接节点共布置32颗或24颗螺栓,是一种可以应用于大跨或重载钢结构的新型节点形式。由于该节点形式的螺栓数量明显多于传统构造,节点安装时螺栓的施拧顺序以及施拧后螺栓的预拉力松弛对该节点中螺栓总体预拉力水平的影响比传统节点更为复杂。采用4种不同的施拧顺序对4个足尺超大承载力端板连接节点试件安装过程中螺栓的预拉力进行了分析,监测了施拧完成后65 h内螺栓的预拉力变化。结果表明,相关规范中规定的螺栓施工预拉力要求适用于超大承载力端板连接节点,提出了该节点螺栓施拧顺序的建议以及多螺栓接头中螺栓施工预拉力的确定方法。     

钢管柔性法兰偏心受拉承载力特性分析及其计算理论

柔性法兰节点通过内外两道角焊缝传力,具有安装快捷、加工简单且省材省时等特点,以柔性法兰的法兰板厚、连接螺栓的内外边距比、预紧力以及轴拉力的偏心距大小为参数,建立柔性法兰节点的非线性有限元模型,分析不同参数下柔性法兰的承载力特性以及螺栓受力特点、应力分布及发展。结果表明:法兰板厚度和螺栓边距比对法兰偏心受拉承载力和最大受力螺栓轴力作用影响较大,其他因素影响较小。最后,研究并提出柔性法兰偏心受拉承载力计算理论,相对轴心受拉时柔性法兰连接螺栓受力修正系数应适当增大,建议修正系数m取为0.8。     

全装配式外套筒-加强式外伸端板组件梁柱连接节点抗弯承载力研究

提出全装配式外套筒-加强式外伸端板组件梁柱新型连接节点,通过理论分析、试验研究和有限元分析,确定了节点受力计算模型,推导出节点抗弯承载力理论计算式,并与有限元模拟值和试验结果进行比较,三者吻合较好,证明其具有合理性和良好的适用性。所提出的节点抗弯承载力计算方法可为该类节点的设计和计算提供理论工具。试验研究与有限元分析还表明,装配式外套筒-加强式外伸端板组件梁柱连接节点的屈服机制为:外套筒和柱壁内凹受压屈曲、外伸端板压屈、节点屈服;梁柱连接节点具有良好的耗能能力,增大外套筒厚度,节点屈服荷载增加,耗能能力提高。     

Finite element analysis on the static behaviour of wide-type large capacity end-plate connections

Compared to the traditional two-column-bolt layout, the wide-type end-plate connections with four bolts in a row could resist a greater moment. In this paper, a detailed verified finite element model is employed to analyse the static behaviour of six wide-type end-plate connections, where parameters such as the end-plate thickness, bolt layout, extended or flushed end plate and the geometry of the stiffener are covered. The simulation results demonstrate that (1) in the elastic range, the transferred tension force of the bolts far from the beam web is about 0.33～0.67 times that of the closer ones; (2) the shear force in the bolts is tiny; (3) at the ultimate state the bolts located far from the beam flange have a significant contribution to the loading capacity of the connection while it shows little contribution in the elastic state. In addition, a yield-line model of the tension part of the end plate is proposed.     

箱形节点域外伸端板弱轴连接的滞回性能研究

提出了一种适用于H形柱的箱形节点域外伸端板弱轴连接,利用有限元软件ABAQUS对8个不同构造形式的端板连接进行了研究,分析了节点的破坏形式、弯矩 转角滞回曲线、承载能力及转动能力等。结果表明:8个不同构造形式的端板连接均为半刚性节点;在循环荷载作用下,箱形节点域端板连接节点的破坏均出现在端板上,而柱子节点域基本完好;当层间位移角为0.04 rad时,各节点的承载力均大于0.8倍钢梁全截面塑性弯矩;端板外伸加劲肋的设置使节点的极限承载力提高10%左右,但耗能能力却下降了4%,建议外伸端板不另设加劲肋;端板厚度为16 mm,即与蒙皮板厚度相差较小时,节点的承载能力、耗能能力较好;提升端板材性能提高节点承载能力,但端板材性提升过大反而会降低节点耗能能力,建议端板材性只提高1个等级。     

Comparison of bolted end plate and T-stub connections sensitivity to bolt diameter on cyclic behavior

Considering the construction limitations, proper and correct design of connections is vital and of great importance. At the construction stage, it is probable to use a connection bolt with a diameter less than the design assumptions. It can occur due to an imperfection in construction or even to changes in the function of the building. The unforeseen changes can increase the structural load, and consequently the moment and shear force demand values. Therefore, the present paper is aimed to examine the sensitivity of the bolted connections to the diameter of bolts using a numerical method. The results show that bolted T-stub connections are more sensitive to bolt diameter than end plate connections. Hence, the bolted end plate connections are recommended where the imperfection in construction or changes in function of the building is probable. Moreover, in construction of bolted connections, if changing the number of bolts regarding the constant total cross sectional area is considered, it is recommended to use the symmetric arrangement of bolts on each beam flange. In design of connections for a particular frame according to AISC, the moment capacity of T-stub connection is higher than that of end plate connection. However, the total energy absorptions of these connection types are approximately equal.     

Seismic strengthening of weak bolted end plate connections using welded haunches

Bolted steel connections have been frequently used after Northridge earthquake. Among the concerns regarding the poor performance of weak connections is the ability to effectively and economically rehabilitate steel moment connections in existing buildings. Strengthening of these connections without the need for changing or replacing their components is a problem that has been recently considered by engineers. This study develops and experimentally validates an innovative technique for enhancing the seismic performance of steel beam to column moment connections. The use of haunch as a way to rehabilitate end plate bolted connections with weak end plate or bolts is studied constructing 6 experimental specimens of corner connections under SAC (Structural Engineers Association of California) cyclic loading protocol. The results of the study show that this strengthening method improves the cyclic behavior of the weak connections. Besides, it provides specimens with better performance than that of the reference connection designed according to AISC. The moment capacity, initial rotational stiffness and energy dissipation of the rehabilitated connections are averagely higher than those of the reference connection by 25, 10 and 12 percent respectively. Moreover, the failure potential in the connection is reduced because the plastic hinge is kept away from connection region and is transferred to the haunch end. It should be noted that this strengthening method is more efficient for cyclic behavior of a bolted connections with weak end-plate than a bolted connection with weak bolts, since the moment capacity is more increased.

     

平端板连接半刚性梁柱组合节点的转动能力

本文在现有研究成果基础之上,针对连接分别承受正、负弯矩作用的情况,给出了平端板连接梁柱组合节点转动能力的计算方法,考虑了钢筋的伸长变形、螺栓的伸长变形、栓钉的滑移变形、混凝土楼板的压缩变形等因素。利用本文给出的方法计算得到的连接转角,是组合节点转动能力的下限值。     

Numerical study on seismic behaviors of steel frame end-plate connections

In order to study the seismic behaviors of steel frame end-plate connections, an efficient and accurate finite element model of ABAQUS was established subjected to cyclic loadings. Element types, material cyclic constitutive models and contact models for bolts, end plate and members were described. Geometry and material nonlinearity were adequately considered. The simulated results of numerical models were verified by typical quasi-static tests of end-plate connections, including both hysteretic curves and failure modes. It provided a strong tool for investigating the performances of this kind of connection. Based on the verified models, connections with different connection methods were established to investigate the effect of connection methods on behaviors of connections, including fully welded connection, extended end-plate connection and flush end-plate connection. The carrying capacity, initial stiffness, hysteretic behaviors, degraded characteristics, fracture tendency index, failure modes and energy dissipation capacity were compared and discussed in depth. The results showed that: If the beam and column are reliably connected, the extended end-plate connection can obtain the same ultimate carrying capacity and initial stiffness (monotonic behaviors) as the welded connection, however, their hysteretic curves, degradation developing curves, and fracture tendency were quite different. It indicated that the connection methods could significantly affect the cyclic behaviors. The stiffeners of end-plate connection could be treated as the first defense of connection, effectively changing the failure mode and avoiding brittle fracture. Therefore, in the high seismic zones, hysteretic behaviors, failure modes and seismic ductility should be taken into account comprehensively to choose the appropriate connection methods.     

半刚性端板节点在循环荷载作用下的非线性有限元分析

运用有限元数值分析软件ABAQUS建立半刚性端板节点模型,对其在循环荷载作用下进行非线性有限元分析,并与相应的试验结果进行了比较验证.结果表明:用ABAQUS建立的有限元模型能够准确地模拟端板节点在循环荷载作用下的整体受力性能,为进一步运用该模型对各种不同形式和构造的端板节点进行全面的有限元非线性参数分析计算提供了正确依据.并分析得出了端板厚度、螺栓直径、螺栓布置、端板加劲肋等因素对端板节点承载力、极限转动能力、耗能能力和延性的影响特性,为半刚性端板节点的抗震设计提供了参考依据.     

方钢管混凝土穿芯高强螺栓-端板节点滞回性能研究

对3个方钢管混凝土柱穿芯高强螺栓-端板节点试件进行了伪静力试验研究。采用有限元程序ANSYS对节点进行了循环荷载作用下的三重非线性有限元分析,研究了轴压比、混凝土强度、高强螺栓预拉力、端板厚度及端板加劲肋等因素对节点滞回性能的影响。结果表明,轴压比和混凝土强度对节点滞回性能影响较小,减小高强螺栓预拉力将显著降低节点的耗能能力,端板加劲肋和端板厚度对节点性能有明显的影响,但设置加劲肋比增加端板厚度对改善节点性能更有效。试验与计算结果表明,穿芯高强螺栓-端板节点具有很好的强度、刚度、延性和耗能能力。