预制节段拼装梁接缝抗剪性能及可靠性研究

As joints exist in the as-built segmental reinforced concrete girder, integrality of the segmental girder is worse than the girder integrated cast-in-site. Shear performance of the joint, which plays important role on the girder integrality, should be paid more attention. Meanwhile, uncertainty of the parameters, which is inevitable in the precast and construction of the girder, does have effect on shear performance of joint..This study focuses on the shear performance of the joint in segmental girder. The influence of three mainly factors, multi-key effect, joint types and pre-stress level, on the shear performance of joint will be investigated. Discount effect of the shear capacity caused by discrepancy among the stress in the shear keys is also studied. Experiment on shear performance of joint will be conducted, and a comprehensive model considering these factors will be proposed. Non -probabilistic reliability evaluation method will be adopted based on the scope of design parameters obtained from experiment study. The calculated reliability will be used to calibrate design partial coefficient for segmental box girder design. .The work of the proposal focus on the statistical character of material and structural parameters in the joint and their influence on the integrality of segmental girder, which is innovative and meaningful for the design and construction of the segmental box girder.

预制节段拼装梁中接缝的抗剪性能对结构整体性有很大影响。对于箱型截面梁，闭环截面内存在剪力流，接缝抗剪性能难以准确评估。节段工厂预制及现场安装过程中的不确定性也使接缝抗剪性能难以准确预测。.本项目针对多键接缝抗剪性能的随机特性及其可靠度展开研究。主要考虑接缝类型和预应力的影响，以及由于多个剪力键不均匀受力而导致的多键效应，分析其对多键接缝抗剪性能的影响。拟开展多键接缝截面抗剪性能试验，建立多因素影响下的多键接缝界面抗剪性能分析模型。考虑节段生产过程及拼装过程中的多重不确定性，基于试验研究所确定的主要影响参数的取值范围，采用非概率可靠度分析方法对接缝抗剪极限状态可靠度进行评估，提出节段拼装桥梁接缝设计分项系数建议值。.本项目针对节段拼装梁接缝处材料及结构参数的随机特性及其对构件整体性能的影响这一关键问题展开研究，具有理论难度与明确的创新性，成果对预制节段拼装箱梁的设计建造具有重要价值。

预制节段拼装梁便于桥梁进行工业化建造，在工程中得到广泛采用。节段间接缝的抗剪性能将对节段拼装梁承载能力产生重要影响。本研究将多个剪力键共同贡献接缝抗剪承载能力的行为模拟为多个剪力键并联的结构体系，当所有剪力键均失效时，结构发生抗剪破坏。同时，基于节段拼装梁接缝中键齿破坏为脆性破坏的特点，考虑单个键齿破坏后界面内的内力重分布过程，建立接缝界面剪切破坏过程分析模型。相应的，可得到n单元并联结构体系在荷载作用下的失效概率。从而得到多键接缝抗剪承载能力的均值和标准差。相应的即可得到节段拼装梁多键接缝满足抗剪承载能力设计值的概率，即预制节段拼装梁接缝的抗剪可靠性计算模型。并给出考虑多键效应的预制节段拼装梁接缝抗剪承载能力折减系数取值。开展文献调研，建立预制节段拼装梁接缝直剪性能数据库，并开展双缝预制节段拼装构件抗剪性能试验，基于数据库中数据和试验数据验证了所建立概率化模型的有效性。.建立了节段拼装梁抗剪性能数值模型，从单元类型的选取、复合受力状态下混凝土材料的本构模型、接缝界面的接触行为三个方面对剪力键位置的精细化模拟进行研究。基于建立的数值模型分析策略，开发了预制拼装混凝土接缝键齿直剪性能分析的参数化建模分析工具。结合既有文献研究中的剪力键抗剪性能试验结果，采用本项目建立的数值分析方法进行实例分析，验证了建立的分析方法的有效性。开展预制节段拼装接缝抗剪性能试验及节段拼装梁弯剪性能试验，对所建立的模型进行验证。基于所建立数值分析模型，对接缝胶层、键齿数目、预应力度、接缝匹配缺陷等因素对接缝抗剪性能的影响进行了分析。提出预制节段拼装梁抗剪承载能力简化模型，揭示节段梁在弯剪作用下的破坏机制。