【作者】 曾磊；

【导师】 吴敏哲； 郑山锁；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2008， 博士

【摘要】 型钢高强高性能混凝土结构作为高技术混凝土材料和新型结构体系的有机结合,具有优良抗震性能和耐久性能。本文针对型钢高强高性能混凝土框架节点进行了系统研究,主要研究内容及成果概括如下:(1)从提高结构耐久性及改善型钢与混凝土之间粘结性能的角度研制了适用于型钢混凝土结构的高强高性能混凝土。深入分析了混凝土高强高性能化的技术途径,进行了大量的混凝土配合比试验,并基于型钢混凝土粘结滑移理论,以混凝土经济成本和混凝土与型钢的协同工作能力为目标函数,进行了非线性多目标混凝土配合比优化设计。对所研制的高强高性能混凝土的拌合物性能、破坏特征及力学性能进行了试验研究,综合已有研究成果确定了其应力应变本构模型,并对高强高性能混凝土耐久性及其试验方法进行了分析。(2)对于可能在工程结构中大规模使用的C60～C100强度等级的混凝土,进行了5榀型钢高强高性能混凝土框架中节点在低周反复荷载作用下的试验研究,试验参数考虑了混凝土强度和柱轴压比的变化。通过试验实测的荷载位移水平、应力分布及裂缝开展情况研究了节点的破坏过程、破坏机理、承载能力、延性及耗能性能,提出了型钢高强高性能混凝土框架节点在低周反复水平荷载作用下的裂缝模式,探讨了混凝土强度和轴压比对节点受力性能的影响。试验结果表明,尽管节点核心区最终发生剪切破坏,各试件仍然具有良好的延性和耗能能力,说明该类节点具有良好的抗震性能。(3)根据试验所得的滞回曲线和骨架曲线,分析节点的滞回规律及恢复力特性,提出了适合于型钢高强高性能混凝土框架节点的恢复力模型,为节点抗震性能研究和非线性地震反应时程分析提供科学的理论基础。根据不同荷载水平下的变形和滞回耗能性能,对节点试件的损伤性能进行了分析比较,确定影响节点损伤的因素,对试验框架节点的损伤指数进行了分析计算,并对试验研究结果进行了损伤量化,提出了适合于型钢高强高性能混凝土框架节点的基于变形和累积耗能非线性组合的地震损伤模型。(4)采用分离式三维实体模型,考虑各种材料的非线性及型钢与混凝土之间的粘结滑移,对型钢高强高性能混凝土框架节点试件进行了有限元分析;通过合理的单元选取及网格划分,较为精确地分析了节点在单调和低周反复荷载作用下的受力性能,特别是节点核心区应变分布,以弥补试验研究中无法直观了解细部受力情况的缺陷。将有限元分析结果与试验研究进行了对比验证,并考察了混凝土强度和轴压比对节点受力性能的影响。通过有限元模型参数的调整进行了数值模拟,定量分析了高强度混凝土脆性对节点抗剪承载能力的影响。(5)基于试验研究和有限元分析结果,进行了节点核心区受力及传力机理分析,确定了节点抗剪的各组成部分,并定量分析了各部分在不同受力阶段对节点抗剪能力的贡献。确定了节点抗剪计算中混凝土强度影响系数,以考虑高强度等级混凝土脆性对抗剪能力的影响,提出了型钢高强高性能混凝土框架节点抗裂、抗剪承载能力计算公式,公式中考虑了混凝土脆性和轴压比对节点承载能力的影响。更多还原

【Abstract】 As an optimized combination of high-tech concrete material and new-style structure, Steel reinforced high performance and high strength concrete structure (SRHSHPC structure for short) possesses excellent seismic behaviour and good endurance. The paper is devoted to studying on seismic behavoirs and design method of SRHSHPC frame joints. The main content is described as follows:1. To improve endurance of Steel reinforced concrete structure (SRC structure for short) and solve the bond-slip problem between steel and concrete, high strength and high performance concrete (HSHPC for short) applied to SRC structure is studied. The technical method to strengthen concrete and increase endurance is analyzed. Orthogonal test is done, and a multi-objective and nonlinear optimal mathematic model is established based on the bond-slip theory between steel shape and concrete, which takes the materials cost and bond strength as objective functions, and takes the other performance indexes of HSHPC as constraint conditions. Based on large amounts of experiments, the working mechanism of HSHPC is analyzed and stress-strain constitutive model of HSHPC is established based on the existed achievement.2. Cyclic loading tests were carried out on five half-scale interior joints to understand mechanical characteristics and seismic behaviors of SRHSHPC frame joints. The test parameters taken into account are concrete strength and axial column load. The study includes joints’ mechanical character, stress distribution, crack development, failure mode, ductility and energy dissipation under cyclic load. A typical crack pattern is provided which can well reflect mechanical character and damage process of SRHSHPC frame joints. The influence of concrete strength and axial column load is analyzed. Though failure mode is panel shear failure, the joints’ deformation and ductility factor can reach a high level, which indicates that SRHSHPC frame joints possess excellent seismic behaviors.3. According to seismic hysteresis curve and skeleton curve obtained from tests, restoring force characteristics of SRHSHPC frame joints including ductility, energy dissipation, and strength and rigidity degradation are analyzed. Based on the test results and numerical analysis, rigidity degradation rules and hysteretic rules are analyzed. A trilinear hysteretic model considering rigidity degradation is proposed for steel reinforced high strength and high performance concrete frame joints. The proposed restoring force model tallies with the test curves, which can be a good reference for seismic design of SRC structures. A seismic damage model applying to SRHSHPC frame joints is put forward, which takes deformation and cumulative damage into account. The damage performance of five tentative frame joints is compared and analyzed according to deformation and dissipated hysteretic energy under different loading levels, and the main influence factors on damage performance are established. The damage indexes of tentative frame joints are calculated, and the influence of strength of concrete and axial compression ratio on damage performance is discussed. The damage model presented can be a reference for seismic damage analysis of structure, prediction of earthquake damage in future, estimation of economic loss and repair after earthquake.4. Finite element analysis applying 3D solid elements and including material nonlinear and bond-slip between steel and concrete is presented. The bearing capacity and mechanical performance of joints under monotonic and cyclic loading is analyzed. The results of nonlinear finite element analysis can show the stresses distribution in the joints better, which provides the possibility to patch up the defects that couldn’t be observed in experiments in detail. The results of finite element analysis are confirmed through contrasting with the test ones and the influences of axial compression ratio and concrete strength on the seismic behaviors of frame joints are discussed. Based on adjustment of model parameters in finite element analysis, the factor of brittle property of high strength concrete influencing on the shear capacity is analyzed.5. The resistant mechanism and failure pattern of SRHSHPC frame joints are analyzed based on experiment and finite element analysis. Horizontal resisting elements are determined, and contribution of each part at different loading stage is analyzed quantitatively. The factor of brittle property of high strength concrete influencing on the shear capacity is determined according to finite element analysis. The practical calculating formulas of crack resistance and shear bearing capacity of such joints were derived, in which the influence of concrete strength and axial column load are included.更多还原