【作者】 孙昊；

【导师】 钱永久；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 桥梁结构是交通运输网络中的控制性工程,确保桥梁结构的安全具有重大的社会意义和经济价值。早期修建的钢筋混凝土拱桥普遍存在着结构老化、整体性差、承载力偏低等病害,已不能满足当地交通和经济发展的需要,需要进行加固补强。采用套箍技术加固既有钢筋混凝土拱桥,不仅能够治理既有的缺陷与病害问题,而且还可以提高结构的整体性能和承载能力。鉴于目前国内外对套箍加固后组合截面的计算理论及其破坏机理与特征进行的相关研究较少,本文围绕教育部《高等学校优秀青年教师教学科研奖励计划(A0110719950102)》的子课题“既有桥梁的维修加固方法研究”,着重开展了以下几个方面的研究工作：1.在收集已有研究成果及资料的基础上,结合作者从事的现场桥梁检测、评估与加固工作,总结了既有钢筋混凝土拱桥容易产生的病害问题,并剖析其产生的机理,为今后同类桥梁结构的设计和维修加固提供可靠的技术资料。同时指出了套箍加固技术可以解决的相关病害问题,指出了开展套箍技术加固钢筋混凝土拱桥研究的必要性。2.针对桥梁加固中新老混凝土结合面处理方式经常出现植入钢筋和开槽的技术方案比选难题,设计了6个试件比较了植入钢筋与开槽两种不同处理方式下的新老混凝土抗剪性能和破坏形式。试验结果表明,植入钢筋的新老混凝土结合面的抗剪性能明显高于开槽的处理方式,植入钢筋的试件破坏具有延性破坏特征,而开槽试件破坏有明显脆性破坏的特征。对植筋情况下结合面的抗剪承载能力计算公式进行了一定的修正,讨论了新老混凝土结合面的植筋率问题,并针对新老混凝土结合面的处理提出了合理的建议。3.采用第三章提出的新老混凝土能够共同工作的建议,设计了考虑不同因素的8组25个套箍加固短柱模型,进行了套箍加固短柱的破坏试验和有限元分析,验证了第三章提出的新老混凝土能够共同工作的建议是可行的。明确了套箍加固后组合截面的破坏过程和破坏机理,分析了不同因素对加固后组合截面承载能力的影响。同时结合试验结果和有限元计算结果,分析了不同加载方式对新老混凝土结合面剪应力和构件承载能力的影响,并针对套箍技术加固中可能出现的不利受力方式提出了应对措施。4.在总结偏心受压承载能力计算相关研究成果的基础上,指出了现行规范计算公式的缺陷,推导了相对精确的统一的偏心受压计算公式。根据套箍加固试验结果,提出了考虑多种影响因素的套箍加固短柱承载能力的计算公式,并结合本次试验的具体处理措施进行了适当的简化,通过简化计算结果与试验结果的比较分析,结果表明提出的简化分析公式比较可靠。5.基于钢筋混凝上结构设计的基本原理,结合套箍加固短柱模型试验研究成果,提出了考虑多种影响因素的套箍技术加固钢筋混凝土拱桥的承载能力计算公式,并结合现有加固技术规范对该公式进行了适当的简化。对套箍加固偏心受压构件二次受力过程的应力状态进行了分析,并考虑了新增混凝土收缩徐变对截面应力的影响。结合钢筋混凝土拱桥自身的特点,推导了不同情况下套箍加固后组合截面承载能力的计算公式。同时,根据套箍加固截面应力的计算过程,建立了关于套箍加固层厚度的简化临界状态方程,结合桥梁加固施工中对浇筑混凝土厚度的要求,能够初步确定套箍加固层的最小合理厚度。6.考虑实际工程应用和第三章提出的新老混凝土能够共同工作的建议,设计并制作了套箍加固钢筋混凝土拱肋和整体浇筑拱肋两个模型试件,分析了套箍加固后组合截面的破坏过程、破坏形式和结构的承载能力。结果表明,套箍加固拱肋与整体浇筑拱肋的裂缝分布及走向、破坏形式和破坏荷载基本一致,说明了第三章提出的新老混凝土能够共同工作的建议是可行的,同时也验证了套箍技术加固钢筋混凝土拱桥是可靠的。7.结合两座大跨度钢筋混凝土拱桥的维修加固工程实例,对套箍加固技术的应用进行了分析。结合理论研究和试验成果,对加固设计方案和套箍加固后关键截面的承载能力进行了分析与计算,并分析了套箍加固后组合截面在运营荷载下的工作性能。加固后的桥梁荷载试验结果验证了套箍技术加固钢筋混凝土拱桥是可行的和可靠的。8.总结了套箍技术加固既有钢筋混凝土拱桥设计分析中的关键问题并有针对性地提出了合理的建议,对套箍技术加固设计的计算步骤提出了规范化的建议。更多还原

【Abstract】 Bridge structure is the controlling engineering of the entire transportation network. To ensure the safety of bridge structures is of great social significance and economic value. There are many deterioration problems of the early built reinforced concrete(RC) arch bridge, such as aging, poor integrity, lower capacity, and so on. Because these bridges can not meet the needs of local transportation and economic development, they must be strengthened in order to increase the load carrying capability and traffic capacity. The hooping strengthening technique not only can resolve defects and deterioration problems of existing reinforced concrete arch bridge, but also can improve integrity performance and increase carrying capacity. However, research either domestic or oversea about the calculation theory and its failure mechanism and characteristics of hooping reinforced composite section is less. Considering above all. combined the sub-research of "the study of the repairing and strengthening method for existing bridge" with the fund supported by the Ministry of Education, several aspects were mainly concerned with as following:1. Based on the research of previous studies and data collection, and combined the on-site bridge inspection, evaluation, and strengthening work that the author has engaged in. the status of deterioration problems for the existing reinforced concrete arch bridge were summarized, and the generating mechanisms were analyzed. Those can provide reliable technical information for the future design, maintenance and strengthening of the similar structures. At the same time, the related deterioration problems resolved by the hooping strengthening technique were pointed out, which leads to the necessity of the research about the hooping technique strengthening existing RC arch bridge.2. Aiming at the technical selection problem appeared frequently in the bridge strengthening about the young-old concrete interface treatments between bonded rebars and grooved.6groups of specimens were made to compare with the shear performance and failure modes of the young-old concrete interface. The test results showed that the young-old concrete interface shear strength of the specimens which embedded steel bars was distinctly stronger than that of the slotted specimens. And the failure characteristics of specimens which embedded steel bars are ductile, but the failure characteristics of specimens which slotted are brittle. For the case of bonded rebars treatment, some amendments on the shear bearing capacity formulas were executed. The bonded rebars ratio of the young-old concrete interface was discussed. And some reasonable suggestions of young-old concrete interface treatment were proposed. 3. By use of the proposed suggestions about young-old concrete working together in the third chapter, and considering the different influence factors.8groups with25column specimens were designed and manufactured. The failure tests and nonlinear FEM analysis of the RC hooping strengthening columns were executed. It verifies that the proposed suggestions about young-old concrete working together in the third chapter are feasible.The failure process and failure mechanism for the composite section after strengthening and the influence of the different factors to the bearing capacity were studied. At the same time, combined with the results of test and FEM, the influence on shear stress of young-old concrete interface and carrying capacity induced by different loading method was analyzed. The counter-measures of unfavorable force mode appeared possibly in hooping technique strengthening were put forward.4. Based on the related research achievements about bearing capacity of eccentric compression member, the defects in the formulas of the current specifications have been pointed out. And the relatively accurate and unified formulas of eccentric compression member have been derived. The formula of bearing capacity for the hooping strengthening columns were proposed, which can consider various influence factors. Then, combined with the specific treatment in this experiment, the formula were appropriatly simplified. By comparative analysis of the calculation and test results, it tests that the simplified formula are reliable.5. Based on the basic design principles of RC structure, combined with the research results of hooping strengthening columns, the formula for the bearing capacity of hooping strengthening structure considered various influence factors was proposed. And considering the existing strengthening technical specifications, the formula was appropriately simplified. The stress states of the secondary loading process for hooping strengthening eccentric compression members were analyzed, and the influence on the sectional stress induced by the shrinkage and creep of fresh concrete was considered. With the feature of RC arch bridge, the bearing capacity formulas of composite section under different conditions were derived. Meanwhile, the simplified critical state equations about the thickness of hooping reinforcement layer were established according to the stress calculation process. Combination of the requirements of the thickness for bridge strengthening construction, the minimum reasonable thickness of hooping reinforcement layer can be initially determined.6. Considering the practical application of engineering and the proposed suggestions about young-old concrete working together in the third chapter, the RC arch rib specimen with hooping strengthening and the integrated pouring specimen were designed and manufactured. The failure process, failure mode and the bearing capacity of the composite section after hooping strengthening were studied. The test results showed that the crack features, failure mode and failure load of the two specimens were basically consistent, and the proposed suggestions about young-old concrete working together in the third chapter were feasible. At the same time, it verified that the hooping strengthening technique used in RC arch bridge was reliable.7. Combining with the practice of repairing and strengthening engineerings about two long-span RC arch bridges, the application of hooping strengthening technique was analyzed. Combining with the research results of theoretical analysis and tests, the strengthening design schemes of the bridges and the bearing capacity of key sections after hooping strengthening were analyzed and calculated. Then, the normal working performance of the composite section after strengthening under operating load was analyzed. The load test results after bridges strengthening showed that the hooping strengthening technique was feasible and reliable for the existing RC arch bridges.8. The key issues of the design and analysis about hooping techinique strengthening the existing RC arch bridge were summarized, and the reasonable suggestions were pertinently proposed. Finally, the standardization proposals about calculation procedure of the hooping strengthening techinique were recommended.更多还原