【作者】 肖林；

【导师】 强士中；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2012， 博士

【摘要】 本文针对在钢-混组合结构中使用日益广泛的PBL剪力键展开研究,系统地研究了PBL剪力键的静力性能,并对其疲劳性能进行初步探索。论文总结了部分国内外典型的PBL剪力键推出试验,对比了试验结果之间的差异,根据试件构造特点将已有推出试验构造分为两类,设计了不同构造的推出试验来验证两种构造之间的差异。试验结果表明,两种构造的荷载-滑移曲线、极限荷载、极限滑移量以及破坏过程、破坏形态都存在明显差异。造成两种构造试验结果差异的根本原因是剪力键埋置深度不同,剪力键周边混凝土的应力环境不同。对于钢-混结合梁和钢-混结合段中的PBL剪力键,在进行试验研究时应给予区分。在推出试验结果的基础上,对PBL剪力键力学性能的合理定义进行研究,并给出了各种规格PBL剪力键的设计承载力、抗剪刚度、极限承载力和延性系数。分析了PBL剪力键力学性能的影响因素,综合比较了PBL剪力键设计承载力计算公式的研究成果并根据推出试验结果,提出了综合考虑各种影响因素的PBL剪力键设计承载力计算公式。提出了PBL剪力键的双线性弹簧简化计算模型,建立了PBL剪力键集群的荷载-滑移协调模型；将双线性弹簧简化计算模型应用到PBL剪力键集群的荷载-滑移协调模型中,提出了PBL剪力键集群的简化计算方法,验证了这种计算方法的可靠性,并分析了PBL剪力键集群的荷载分布规律及其影响因素。对PBL剪力键的推出试验展开非线性数值模拟,将试验结果与数值分析结果对比,验证了数值模拟的可靠性。通过数值模拟方法再现了PBL剪力键的破坏过程,结合推出试验结果与数值模拟结果,分析了两类试验构造中PBL剪力键在不同受力阶段的传力机理；对PBL剪力键的破坏机理进行了研究,分析了各种破坏模式的起因,归纳了不同构造参数可能引起的破坏模式及力学性能差异。按照正交试验方法设计了PBL剪力键的数值仿真试验以研究构造参数对力学性能的影响,对仿真试验结果的统计分析表明：PBL剪力键设计承载力的显著影响因素是钢板开孔直径、贯穿钢筋直径、混凝土强度以及开孔钢板厚度,抗剪刚度的显著影响因素是混凝土强度、钢板开孔直径、贯穿钢筋直径及开孔钢板厚度。根据PBL剪力键力学性能影响因素的次序、交互作用以及因素指标变化关系,确定了合理的构造参数。结合钢-混组合结构的实际情况,给出了钢-混结合段与结合梁中PBL剪力键的合理参数取值范围。通过18个试件的疲劳试验,对PBL剪力键的疲劳性能进行了研究。疲劳试验得到了不同疲劳荷载对应的疲劳寿命,以及钢和混凝土之间的残余滑移量与疲劳荷载之间的关系。将静力破坏过程与疲劳破坏过程进行对比,研究了PBL剪力键的疲劳破坏机理。利用极差分析与方差分析方法,分析了PBL剪力键构造参数对其疲劳性能的影响,研究发现在混凝土强度等级相同的情况下,钢板开孔直径及厚度是PBL剪力键疲劳性能的主要影响参数,并且开孔直径的影响更大。建立了PBL剪力键的疲劳荷载与疲劳寿命之间的关系表达式,为评估PBL剪力键的疲劳寿命提供了便利。选取残余滑移量作为损伤变量,按照残余滑移量与荷载循环之间的关系建立了PBL剪力键的二阶段线性疲劳累积损伤演化模型。对PBL剪力键疲劳损伤后的静力性能进行了试验研究,研究结果显示,疲劳损伤使得PBL剪力键的承载力有所降低。对于有贯穿钢筋的PBL剪力键,疲劳损伤使得其抗剪刚度增大,而对于无贯穿钢筋的PBL剪力键,疲劳损伤后的抗剪刚度减小。更多还原

【Abstract】 The PBL shear connector which is increasingly widely used in steel-concrete composite structure is studied in this dissertation. Systematical research on its static performance is conducted, and the fatigue property is preliminarily explored.Some of the typical push-out tests at home and abroad are summarized, and the differences between the results are comparatively analyzed. Based on the construction feature of the test specimen, the push-out configurations are grouped into two categories, and a variety of push-out tests is designed to verify the differences between them. The results show that the load-slippage curve, ultimate load, ultimate slippage, failure process and failure mode are significantly different from each other, reasons for which are the embedment depth of the PBL shear connector and the stress environment of the surrounding concrete. Moreover, the PBL shear connector in steel-concrete composite beam and steel-concrete composite joint should not be generally treated.On the basis of the push-out test results, the reasonable definition for the mechanical property of the PBL shear connector is researched, and the design bearing capacity, shear stiffness, ultimate bearing capacity and ductility factor in various specifications are obtained. The factors influencing the mechanical property of the PBL shear connector is analyzed, and the research achievement of the design bearing capacity formula is overall compared. In accordance with the push-out test results, a regressive design bearing capacity formula considering all kinds of influencing factors is presented.A bilinear spring simplified model for PBL shear connector is proposed, and the load-slippage coordination model for PBL shear connector group is established. Applying the bilinear spring simplified model into the load-slippage coordination model, a simplified calculation method for PBL shear connector group is presented and proved to be reliable. The law of the load distribution of PBL shear connector group and its influencing factors are analyzed.The nonlinear numerical simulation for push-out tests of PBL shear connector is performed, and the numerical results are proved reliable by comparing with test results. The PBL shear connector’s failure process is represented through the numerical simulation method. Combining the results from push-out test and the numerical simulation method, the load transfer mechanism of PBL shear connector at each stage for two configurations is analyzed. On the basis of the research on the failure mechanism of the PBL shear connector, causes of different failure modes are studied, and diversities of the failure mode and mechanical property resulted from different structural parameters are summarized.Based on the orthogonal experimental method, numerical simulation tests are designed to investigate the structural parameters’effect on the mechanical property of PBL shear connector. Statistical analysis of simulation results show that the significant influencing factors of design bearing capacity are successively the diameter of opening hole, diameter of perforate rebar, strength of concrete and thickness of perforate plate, while the factors of the shear stiffness are successively strength of concrete, diameter of opening hole, diameter of perforate rebar and thickness of perforate plate. According to the order and interaction of influencing factors and the relationship between index and factors, the reasonable structural parameters are determined. Considering the actual situation of steel-concrete composite structure, the rational parameter range for the steel-concrete composite beam and composite joint is presented.Fatigue tests of18specimens are carried out to inverstigate the fatigue property of PBL shear connector. The fatigue life and residual slippage corresponding to fatigue load are obtained by fatigue tests. Comparing fatigue failure process with static failure process, the fatigue failure mechanism is studied. Through range analysis and variance analysis, the structural parameters’impact on fatigue performance is studied. The results show that in the case of same concrete strength, the open hole diameter and the thickness of perforate plate are main influencing factors of PBL shear connector’s fatigue performance, and the open hole diameter has greater impact.The relationship between fatigue load and fatigue life is established which provide a convenient to evaluate the fatigue life of PBL shear connectors.The residual slippage between steel and concrete is selected as the damage variable. According to the relationship between residual slippage and load cycles, the two-stage linear fatigue damage accumulation model is proposed. Model tests are performed to investigate the static performance of fatigue damaged PBL shear connectors. The test results show that fatigue damage make PBL shear connectors’bearing capacity reduced, and make the shear stiffness increase for PBL shear connectors with perforate rebar while decrease without perforate rebar.更多还原