【作者】 石卫华；

【导师】 余志武；

【作者基本信息】 中南大学 ， 土木工程， 2013， 博士

【摘要】 钢-混凝土组合梁结构广泛应用于桥梁工程。随着服役时间的增长,在侵蚀环境作用和车辆荷载作用下,组成组合梁结构的部件,如钢梁、混凝土板、钢筋和栓钉,均会产生耐久性损伤,从而导致组合梁结构发生力学性能劣化,如：破坏模式转变、承载能力降低、刚度下降和延性降低；进而引起服役期内组合梁结构的可靠指标不断减小,降低组合梁结构的服役寿命。为确保钢-混凝土组合梁结构的安全运营,同时为组合梁结构耐久性设计、寿命预测、加固和拆除重建等提供技术依据,本文结合国家自然科学基金项目“钢-混凝土组合桥梁耐久性研究(50878216)”和铁道部科技重点计划项目“钢-混凝土组合铁路桥梁耐久性技术措施研究(2007G031)”,围绕钢-混凝土组合桥梁耐久性研究中的关键科学问题,以提高钢-混凝土组合桥梁耐久性为目的,从锈蚀栓钉力学性能、锈蚀栓钉连接件力学性能、栓钉锈蚀后钢-混凝土组合梁抗弯承载力、时变可靠性研究等方面开展系统深入的研究。主要工作包括：(1)通过对三种截面形式的栓钉连接件进行了人工气候环境条件下氯离子侵蚀试验,研究了栓钉连接件的氯离子侵蚀路径,比较了三种截面形式的的栓钉连接件抗氯离子侵蚀性能,建立了钢板与混凝土结合面氯离子侵蚀规律。(2)通过对人工气候环境加速锈蚀和恒电流加速锈蚀得到的锈蚀栓钉进行的拉伸试验,研究了锈蚀栓钉性能退化机理,建立了锈蚀栓钉名义屈服强度、抗拉强度、伸长率及弹性模量与锈蚀率之间的定量关系模型,并在此基础上,建立了锈蚀栓钉的本构关系模型。(3)通过对国内外普通混凝土实心板推出试验的回归分析,建立了考虑栓钉和混凝土相互影响的栓钉连接件抗剪承载力计算公式；采用该公式对本文推出试验结果进行了分析和比较。建立了栓钉连接件荷载-滑移曲线的计算模型。对10个锈蚀栓钉连接件进行了推出试验,得到了抗剪承载力、破坏形态和荷载-滑移曲线,建立了栓钉锈蚀后栓钉连接件的抗剪承载力、剪切刚度、极限滑移值和荷载-滑移关系计算模型。(4)对14个钢-混凝土组合梁进行了通电加速锈蚀试验,并进行了抗弯性能试验。研究了锈蚀钢-混凝土组合梁裂缝特征及分布规律、变形发展规律、跨中截面应变分布规律、结合面相对滑移分布规律、延性变化规律和刚度变化规律。(5)在考虑混凝土翼板保护层锈胀开裂承载力计算模型基础上,考虑栓钉锈蚀后剪力连接程度对组合梁抗弯承载力的影响,引入锈蚀栓钉连接件与混凝土协同工作系数,采用简化塑性理论,结合本文获得的试验数据,提出了组合腐蚀效应下钢-混凝土组合梁抗弯承载力计算公式。通过实例验证了本文所提出的组合腐蚀效应下钢-混凝土组合梁抗弯承载力计算公式的合理性。(6)基于抗弯承载力极限状态,提出了同时考虑栓钉锈蚀与荷载效应时变的钢-混凝土组合梁时变可靠度分析方法。采用该方法对除冰盐环境下一座钢-混凝土组合桥梁进行了时变可靠性分析,对影响组合梁时变可靠指标的因素进行了探讨。图83幅,表38个,参考文献244篇。更多还原

【Abstract】 Steel-concrete composite beams are widely used in Bridge Engineering. With the growth of service time, the durability damage will occur gradually for composite beams’main components such as steel beam, concrete slab, reinforcement and stud, and it leads to the mechanical property deterioration of composite beams, such as failure mode transforming, carrying capacity declining, stiffness degradation, ductility reducing and so on. So the reliability index will be reduced gradually and service life will decline in service period for composite beams. To insure safety operation and to provide technology basis for durability design, service life prediction, reinforcement and rebuilt, it is very necessary to carry out research on the mechanical behavior of steel-concrete composite beams considering durability damage. This research project is supported by National Natural Science Foundation under the Project No.50878216"Durability Research of Steel-concrete Composite Beams " and the Research Fund for the Key Program of Ministry of Railways the Project No.2007G031"Research on Durability Technical Measures of Steel-concrete Composite Beams ". Centering on the essential scientific problems existing in durability research on steel-concrete composite bridges, aiming at improving the durability,the systematical and in-depth study have been carried out which includes the mechanical behavior of corrosion stud and stud shear connector after stud corrosion,flexural capacity and time-dependent reliability of composite beams in which stud suffer durability damage.The main research works include as follows:(1) By penetration test of chloride ion for3section types’stud shear connectors under artificial climate environment were carried out, penetration path of chloride ion for stud shear connectors was studied, chloride resisting properties of3section types’stud shear connectors was compared, and erosion rule of chloride ion for combined surface of composite structures was build up.(2)The corrosion studs have been obtained by artificial climate accelerated corrosion method and galvanostatic accelerated corrosion method. Through corrosion studs’ tensile test, the degradation mechanism of mechanical behavior has been studied and quantitative relationship models of nominal yield strength, tensile strength, elongation and modulus of elasticity vs. corrosion rate for corrosion stud. And on the basis of research achievement above, the constitutive model of corrosion stud has been build.(3)Through regression analysis of push-out tests which were conducted by scholars at home and abroad, the calculation formula of shear bearing capacity for stud shear connectors has been build up in which interact influence of stud and concrete was considered. According to the formula, the analysis and comparison on push-out test results which were conducted in this paper has been performed. The computational model of load-slip curve of stud shear connector has been set up. Based on the experimental researches of10stud shear connectors in which stud suffered corrosion, failure model, shear capacity and load-slip curve have been obtained. And on the basis of analysis at experimental results above, The computational model of shear capacity, shear stiffness, ultimate slip and load-slip curve for stud shear connector in which stud suffered corrosion.(4) The galvanostatic accelerated corrosion tests of14steel-concrete composite beams were carried out and the experiments on flexural behavior were conducted. Based on test results, the research on fracture characteristics, fracture distributing, deformation development characteristics, strain distributing in mid-span section, relative slip of joint surface, ductility and stiffness, were carried out.(5) On the basis of flexural strength model of corrosive steel-concrete composite beams considering influence of corrosive cracks in concrete cover, with considering of the effect of shear connection degree on bending capacity after stud corroded, by introducing coordination coefficient of corrosive stud and concrete, adopting simplified plastic theory, by integrate of test results in this paper, the flexural strength model considering combined corrosion effect has been put forward. The validity and rationality of model has been validated thought example analysis.(6) Based on flexural capacity ultimate stage, the analysis method of time-varying reliability for steel-concrete composite beams was put forward, which considered stud corrosion and time-dependent characteristics of load effect. The time-dependent reliability analysis for a steel-concrete composite beams bridge was conducted under de-icing salt condition, and the factors that influenced the reliability index of steel-concrete composite beams were investigated.更多还原