【作者】 闫长旺；

【导师】 贾金青；

【作者基本信息】 大连理工大学 ， 结构工程， 2009， 博士

【摘要】 近年来,随着现代建筑向大跨、高层方向发展,超高强混凝土正得到日益广泛的应用。超高强混凝土的优异性能是具有更高强度和更好的耐久性,但随着混凝土强度等级的提高,呈现出愈来愈显著的脆性。建筑物梁与柱节点的设计是关系到建筑物“大震不倒”的关键,现行《混凝土结构设计规范》GB 50010-2002中规定混凝土强度等级的适用范围为C15～C80,《型钢混凝土组合结构技术规程》JGJ 138-2001中混凝土强度范围为C30～C60,《钢骨混凝土结构技术规程》YB9082-2006中混凝土强度范围为C30～C80。目前对钢骨超高强混凝土框架节点抗震性能的研究并不多见,实际工程的需要与现行规范、规程指导的脱节形成的矛盾变得日益尖锐。针对上述现状,本文选定C100级超高强混凝土为研究材料,以钢骨超高强混凝土框架节点为研究对象,主要进行了以下几个方面的工作:(1)通过低周反复荷载作用下钢骨超高强混凝土柱-钢筋混凝土梁(SRUHSC柱/RC梁)框架节点的试验,分析试验参数轴压比、配箍率和钢骨形式对其破坏形态、滞回性能、延性、耗能、刚度和强度退化、荷载-应变关系等的影响。试验结果表明:相比钢筋混凝土节点,SRUHSC柱/RC梁框架节点的滞回曲线比较饱满,外包面积大,延性较好,耗能能力较强;相同试验参数条件下,轴压比越大或配箍越小,节点的延性越差,耗能较少,刚度和强度退化较快;内置十形钢骨的框架节点与内置工形钢骨的框架节点相比,具有较好的延性和耗能能力,刚度与强度退化较慢。(2)选取我国应用的较广的另一种节点模型—钢骨超高强混凝土柱-钢骨混凝土梁(SRUHSC柱/SRC梁)框架节点,进行低周反复荷载作用下的抗震性能试验研究,试验参数考虑了轴压比、配箍率和钢骨形式的变化。通过试验实测的荷载位移曲线、破坏形态及裂缝开展情况研究了节点的破坏过程、破坏机理、刚度与强度退化、延性及耗能性能,探讨了轴压比、配箍率和钢骨形式对节点受力性能的影响。试验结果表明,该类节点具有良好的延性和耗能能力;随着轴压比的增加或配箍率的减少,延性和耗能能力有明显降低,刚度与强度退化增快:内置十形钢骨有利于改善框架节点的抗震延性与耗能能力,缓减刚度与强度退化。(3)在SRUHSC柱/RC梁框架节点和SRUHSC柱/SRC梁框架节点试验研究的基础上,进一步分析了其受力机理,以及各加载阶段,超高强混凝土、钢骨、箍筋对节点抗剪承载力的贡献,提出了钢骨超高强混凝土框架节点抗剪、抗裂承载能力计算公式。分析结果表明,在反复加载过程中,节点核心区的剪力主要由超高强混凝土承担,极限阶段时,超高强混凝土承担SRUHSC柱/RC梁框架节点核心区剪力的88%左右,承担SRUHSC柱/SRC梁框架节点核心区剪力的73%左右:轴压比的增大,或配箍率的增大,有利于节点抗剪承载能力的提高,而钢骨形式对抗剪承载能力的影响不明显:所提出的SRUHSC柱/RC梁框架节点和SRUHSC柱/SRC梁框架节点的抗剪承载能力和抗裂承载能力的计算方法,抗剪承载能力计算值与试验值之比在0.91～1.02范围内,抗裂承载能力计算值与试验值之比在0.89～1.05范围内。(4)基于试件的破坏形态,确定了钢骨超高强混凝土框架节点的损伤变量,建立了基于变形与强度退化的地震损伤模型,分析了损伤指数与加载位移的关系。通过对结构受力过程中损伤的累积、演变的研究,对损伤发展阶段进行了分析;同时,分析了配箍率、轴压比和钢骨形式对钢骨超高强混凝土框架节点的损伤发展过程的影响。分析结果表明:所提出的地震损伤模型能较好地反映钢骨超高强混凝土框架节点在低周反复荷载作用下的破坏形态,可较客观的评价地震作用下该类节点的损伤状况;加载中、后期,各试验参数对节点试件损伤发展的影响较明显,轴压比较小或配箍率较大的节点试件具有较小的损伤指数,损伤发展较慢,内置十形钢骨形式的节点试件损伤发展较内置工形钢骨形式的节点试件慢。(5)在试验研究的基础上,应用ANSYS-APDL有限元分析软件,对钢骨超高强混凝土框架节点进行了非线性有限元分析。根据试验情况,对有限元模型施加边界约束和荷载作用,通过合理的单元选取和网格划分,较精确地反映了节点试件在低周反复荷载作用下的受力性能;通过对部分节点试件的有限元计算,得到了节点试件的滞回曲线和骨架曲线,将有限元分析结果与试验研究结果进行了对比分析,并通过位移延性系数与等效粘滞阻尼系数讨论了框架节点的抗震延性与耗能能力。更多还原

【Abstract】 Recently, ultra high strength concrete (UHSC) is more and more widely used in the high-rise and long-span buildings because of its higher bearing capability and better durability. But with the increasement of concrete grade, UHSC becomes more and more brittle. The design of beam-to-column connection is the key to prevent building from collapsing in the earthquake. In China, the concrete strength grade is C15～C80 in the new applying "Code for design of concrete structures" (GB 50010-2002), it is C30～C60 in the "Technical specification for steel reinforced concrete composite structures" (JGJ 138-2001), and it is C30～C80 in the "Technical specification of steel-reinforced concrete structures"(YB9082-2006). However, now there is very little of correlative research on seismic performance of steel reinforced ultra high strength concrete frame connection, so the contradiction between engineering requirement and current code or specification becomes more and more serious. In order to solve the above-mentioned problems, the following aspects are carried out in this thesis:(1) Based on the experiments on SRUHSC column to RC beam connections under low cyclic reversed load, influences of axial load ratio, volumetric stirrup ratio and structural steel shape are analyzed on failure mode, hysteretic behavior, ductility, energy dissipation, stiffness or strength degradation and relation between load and strain, et al. The experimental results shows that SRUHSC column to RC beam connections have plumper hysteretic curves, bigger laminal area, better ductility and stronger energy dissipation compared to RC connection, and that ductility becomes poorer, energy dissipated becomes less, stiffness or strength degrades faster with an increase of axial load ratio or decrease of volumetric stirrup ratio. At the same time, the connections with encased + shaped structural steel have better ductility, stronger energy dissipation and slower stiffness or strength degradation compared to ones with encased I shaped structural steel.(2) The SRUHSC column to SRC beam connections used widely are tested under low cyclic reversed load to investigate their seismic performance, and the experimental parameters consists of axial load ratio, volumetric stirrup ratio and structural steel shape. Based on the measured curves of load to displacement, failure modes and crack development, damage process, failure mechanism, stiffness or strength degradation, ductility and energy dissipation are studied. The experimental results shows that the ductility of SRUHSC column to SRC beam connections are better and their mechanical behaviors are influenced obviously by experimental parameters. Besides, the ductility and energy dissipation capacity become poor with an increase of axial load ratio or decrease of volumetric stirrup ratio, and are improved due to encase + shaped structural steel.(3) Based on the experiments of SRUHSC column to RC beam connections and SRUHSC column to SRC beam connections, mechanical behavior and respective contribution to shear capacity are analyzed overall. Calculation methods of shear and crack resistance are presented. The results shows that ultra high strength concrete bears most part of shear capacity in the course of experiment with 88% for SRUHSC column to RC beam connections and 73% for SRUHSC column to SRC beam connections, that shear capacity is possible improved with an increase of axial load ratio and volumetric stirrup ratio, and that structure steel shape has less influence on shear capacity of connection. The ratio of calculated values to experimental values ranges from 0.91 to 1.02 for shear capacity and the ratio of calculated values to experimental values ranges from 0.89 to 1.05 for crack capacity.(4) Based on the failure mode, damage variables of steel reinforced ultra high strength concrete frame connection are determined and damage model consisted of deformation and strength degradation is presented. Damage development and relation between damage index and displacement are analyzed by damage accumulation and damage evolution in the course of loading. The results show that damage model describes failure mode of steel reinforced ultra high strength concrete frame connection under the low cyclic reversal load and evaluates damage behavior objectively. The damage development is influenced obviously by experimental parameters on the stage of medium-term and final-term loading. With a decrease of axial load ratio or an increase of volumetric stirrup ratio, the damage index becomes smaller, damage develops slower, and + shaped structural steel slows damage development of the connections.(5) The finite element analysis of steel reinforced ultra high strength concrete frame connection is carried on by ANSYS-APDL software based on the experiment. Boundary restraint and load are applied on the FE model according to the loading program. The mechanical behavior of connection is described by reasonable element and meshing under low cyclic reversal load. After FE calculation, hysteretic curves and skeletal curves are obtained, and comparison between FE analysis and experimental results is analyzed. Finally, ductility and energy dissipation capacity are studied according to displacement ductility coefficients and equivalent damping coefficients.更多还原