【作者】 张扬；

【导师】 武振宇；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2011， 博士

【摘要】 钢管结构具有外形美观、结构性能优越、施工工期短等多方面优点,因而在海洋平台、大跨度屋盖、输电线塔、高层建筑等土木工程领域得到广泛应用。钢管节点作为钢管结构的重要组成部分,其性能受到研究人员的长期关注。已完成的研究工作主要集中于钢管节点的静力及高周疲劳性能,并形成了成熟的静力及疲劳设计方法。但对钢管节点抗震性能的研究较少,造成目前在役钢管结构的抗震性能评估及新建钢管结构的抗震设计存在诸多不确定性。有鉴于此,为进一步完善钢管结构的研究和推广使用钢管结构,有必要深入研究钢管节点及钢管结构的抗震性能。本文对Y型矩形管-管节点和Y型纵向板-矩形管节点的滞回性能进行了试验、有限元和理论分析。具体内容如下:(1)进行了10个Y型矩形管-管节点及8个Y型纵向板-矩形管节点的拟静力试验。试验中发现,大多数节点在弦管表面沿某条关键点连线形成穿透裂缝后不久,即由于裂缝迅速扩展导致试验停止。据此提出可将弦管表面沿关键点连线形成穿透裂缝视作节点稳定工作阶段结束的标志,并根据节点稳定工作阶段性能对其滞回性能进行合理评价。试验节点的滞回曲线均比较饱满。通过试验研究了去应力退火处理和几何参数对节点稳定工作阶段滞回性能的影响。结果表明,退火后,节点的延性比及累积能量耗散比明显增大。随支弦管夹角增大,退火管-管节点的延性比略有减小,板-管节点的延性比、累积延性比及累积能量耗散比明显增大。随着弦管宽厚比减小,管-管节点的累积延性比及累积能量耗散比减小。随节点板有效厚度与弦管宽度比增大,板-管节点的延性比及累积能量耗散比增大。(2)基于双线性强化模型及简化的Lemaitre损伤模型,建立了考虑损伤演化的混合强化本构模型,通过编制有限元程序ANSYS的用户子程序实现。给出了利用单轴拉伸材料常数计算材料损伤参数的近似方法。采用此本构模型考虑材料损伤,对本文的节点试验进行了有限元模拟。与试验中节点开裂部位相对应,定义了三维有限元模型的关键体元和关键面域。基于损伤耗散能值,给出了有限元模型中关键部位形成穿透裂缝的判断方法,从而可预测节点的稳定工作寿命。模拟试验的结果表明,本文提出的考虑损伤的有限元法可用于分析Y型矩形管-管节点和Y型纵向板-矩形管节点稳定工作阶段的滞回性能。(3)采用有限元法分析了加载制度对Y型矩形管-管节点和Y型纵向板-矩形管节点稳定工作阶段滞回性能的影响,得出以下结论:1)在等幅对称加载时随位移幅值增大,节点的稳定工作寿命降低,管-管节点的累积延性比和累积能量耗散比先减小后增大,板-管节点的累积延性比减小,板-管节点的累积能量耗散比先增大后减小。2)若位移幅值不变,适当的受拉或受压平均幅值可以小幅提高管-管节点的稳定工作寿命,并导致管-管节点的累积延性比、累积能量耗散比增大;但受拉或受压平均幅值降低了板-管节点的稳定工作寿命,并导致板-管节点的累积延性比和累积能量耗散比减小。通过有限元分析,给出了稳定工作阶段滞回性能较好的节点几何参数范围,可供工程应用时参考。(4)基于有限元分析结果,提出了Y型矩形管-管节点和Y型纵向板-矩形管节点的简化恢复力模型,通过编制ANSYS程序的用户自定义单元子程序实现。采用自定义单元模拟本文的节点试验,得到的滞回曲线与考虑损伤的三维有限元模型计算所得曲线吻合较好。在对整体结构的抗震性能进行有限元分析时,采用自定义单元替代三维有限元模型来模拟节点的滞回行为可显著简化有限元建模及分析过程。(5)鉴于Y型矩形管-管节点和Y型纵向板-矩形管节点良好的滞回性能,提出了利用上述节点耗能的支撑体系。选取文献中单层单跨框架结构作为基本结构,采用含Y型矩形管-管节点的人字形管支撑对基本结构进行抗震加固,用有限元法分析了加固效果。与文献中采用的光面钢板剪力墙、带波纹钢板剪力墙、有无钢立柱约束屈曲的单斜方钢管支撑及有无钢立柱约束屈曲的X型钢杆支撑等六种支撑的加固效果相比,结果表明,尽管采用含管节点的支撑体系加固后结构的初始刚度偏低,但综合考虑加固后结构的变形能力、耗能能力和经济性能,发现含管节点的支撑体系加固效果较好,且加固后结构的耗能性能稳定。可见,本文提出的新型管支撑具有良好的应用前景。更多还原

【Abstract】 Steel tubular structures are widely used in civil engineering fields such as offshore platforms, large span roofs, transmission line towers, and high-rise buildings for their advantages such as the graceful shape, structural efficiency, and short construction period. As an important part of the tubular structure, the tubular joint has been studied for a long time. Completed researches mainly focused on the static and high cycle fatigue properties of tubular joints, from which, static and fatigue design methods have been proposed. However, only a little research work on the seismic properties of tubular joints has been carried out, leading to many uncertainties in seismic performance assessment of in-service tubular structure and seismic design of new tubular structure. In view of those facts above and to improve the research on tubular structure and promote the application of tubular structure, it’s necessary to investigate the seismic properties of steel tubular joints and structures thoroughly. In this dissertation, hysteretic properties of Y-type rectangular hollow section (RHS) joints including RHS-to-RHS joints and longitudinal plate-to-RHS joints were analyzed by experimental, finite element (FE), and theoretical methods. The details are as follows:(1) Quasi-static tests of ten Y-type RHS-to-RHS joints and eight Y-type longitudinal plate-to-RHS joints were carried out. For most specimens, the rapid crack propagation led to the test termination, soon after the penetrating cracks formed which located along the curves connecting key points on the chord surface. Thus the formation of the penetrating cracks along the connecting curves of key points could be considered as the symbol of entering unsteady working stage for the joint. And the hysteretic properties of the joint were assessed based on the performance in the steady working stage. The hysteresis curves of tested joints are plump. The influence of stress relief annealing treatment and geometrical parameters on the tested joints’hysteretic properties in the steady working stage was analyzed. It is shown that annealing significantly increases the ductility ratio and the accumulative energy dissipation ratio of the joint. With increasing brace-to-chord angle, the ductility ratio decreases slightly for annealed RHS-to-RHS joint, while the ductility ratio, the accumulative ductility ratio, and the accumulative energy dissipation ratio increase dramatically for plate-to-RHS joint. With decreasing width-to-thickness ratio of the chord, the accumulative ductility ratio and the accumulative energy dissipation ratio decrease for RHS-to-RHS joint. With increasing ratio of the effective thickness of plate to the chord width, the ductility ratio and the accumulative energy dissipation ratio increase for plate-to-RHS joint.(2) Using bilinear hardening model and simplified Lemaitre’s damage model, a constitutive model considering mixed hardening and damage evolution was established and then incorporated into the ANSYS FE code through a user subroutine. Using material properties from the uniaxial tensile test, an approximate method for calculating the material damage parameters was proposed. Considering the material damage evolution using the constitutive model, the aforementioned experiments of the joints were numerically simulated. Corresponding to the cracking zones of the tested joints, key volumes and key areas of the three-dimensional FE model were defined. Based on the damage dissipation energy, the method for judging crack penetrating in key zones was proposed, by which the steady working life of the joint can be predicted. Results of simulating the tests show that the FE model considering material damage evolution can be used to analyze the hysteretic properties of Y-type RHS-to-RHS joint and Y-type longitudinal plate-to-RHS joint in the steady working stage.(3) The influence of loading program on the Y-type RHS-to-RHS joint’s and the Y-type longitudinal plate-to-RHS joint’s hysteretic properties in the steady working stage was analyzed using FE method. It is concluded that: 1) When symmetrical loads with constant amplitudes were applied, with increasing displacement amplitude, the steady working life of the joint decreases, the accumulative ductility ratio and the accumulative energy dissipation ratio of the RHS-to-RHS joint first decrease and then increase, the accumulative ductility ratio of the plate-to-RHS joint decreases, and the accumulative energy dissipation ratio of the plate-to-RHS joint first increase and then decrease. 2) Keeping the displacement amplitude constant, appropriate average amplitude in tension or compression leads to slight increase in the steady working life, the accumulative ductility ratio, and the accumulative energy dissipation ratio of the RHS-to-RHS joint. However, average amplitude in tension or compression leads to decrease in the steady working life, the accumulative ductility ratio, and the accumulative energy dissipation ratio of the plate-to-RHS joint.Using FE analysis, a range of geometrical parameters was given to obtain joints having superior hysteretic properties, which can be referenced in the engineering application.(4) Based on the results of the FE analysis, simplified restoring force model of the Y-type RHS-to-RHS joint and Y-type longitudinal plate-to-RHS joint was proposed, which was incorporated into the ANSYS FE code as a user-defined element through a user subroutine. The user-defined element was then used to simulate the experiments of joints carried out by the author. The calculated hysteresis curves agree well with the curves calculated by the three-dimensional FE model considering material damage evolution. In the FE analysis of the seismic behavior of the overall structure, it can significantly simplify the FE modeling and analysis to simulate the hysteresis behavior of the RHS joint using the user defined element instead of the three-dimensional FE model.(5) In view of the good hysteretic properties of the Y-type RHS-to-RHS joint and Y-type longitudinal plate-to-RHS joint, the RHS bracing system using these two types of joints to dissipate energy was proposed. A single-story, single-bay frame was chosen as the basic structure, which was retrofitted with the chevron RHS bracing system containing Y-type RHS-to-RHS joints. The retrofitting effect was investigated using FE method. Comparing to the properties of basic structures retrofitted with the steel plate shear wall (SPSW) with flat infill, the SPSW with corrugated infill, the single-diagonal RHS bracing member using steel studs to restrain brace against buckling, the single-diagonal RHS bracing member, the crossed-diagonal steel bracing members using steel studs to restrain braces against buckling, and the crossed-diagonal steel bracing members, the structure retrofitted with the bracing system containing RHS joints has better properties considering the deformation capacity, the energy dissipation capacity, and the economic performance synthetically, though it has lower initial stiffness relatively. Besides, the structure retrofitted with the bracing system containing RHS joints dissipated energy stably. Thus it can be seen that the application prospect of the RHS bracing system proposed by the author is bright.更多还原