施工缝的模型化及对RC剪力墙抗震性能影响的研究

Construction joint is inevitable in the cast-in-situ RC structure. Much tests have been done and found that the tensile and shear strength of concrete across construction joint are much weaker than integral concrete. Many seismic damages around construction joints appeared in the 8.0 magnitude earthquake which happened in Wenchuan country at 2008.Which illuminates that construction joint may be a potential vulnerable point where a sliding failure developed.. This project focuses on force transferring mechanics between joint located in the root of shear wall through experimental research, the mechanical properties of construction joints and its affects on the seismic properties of RC component were studied, based on the experimental data and theoretical analysis，the numerical model of construction joint is established.The plastic hinge model and the formula of equivalent plastic hinge length apply to shear wall with construction joint would be established. The influence laws of construction joints on seismic performance of RC shear wall were studied，and the range of considering the effect of construction joints were defined, finally the formula checking the sliding resistance and corresponding design suggestions were given.

现浇钢筋混凝土（RC）结构施工过程中无法实现混凝土的连续浇筑而形成施工缝。已有试验研究表明施工缝处接缝混凝土存在抗拉和抗剪强度低于整浇混凝土的特点。2008年汶川地震中大量的施工缝震害现象和现有的研究表明，目前施工缝的留设位置和处理方法不能保障结构构件具有良好的抗震性能，地震发生时极易形成结构的薄弱环节造成提前破坏。.本项目以地震中破坏较多的剪力墙构件为研究对象，通过拟静力试验研究施工缝基本力学性能的特点和对构件抗震性能的影响，明确混凝土构件在施工缝部位的破坏模式及施工缝处力的传递机制。重点解决施工缝的模型化问题，研究适用于端部带施工缝剪力墙构件的塑性铰模型并给出等效塑性铰长度计算公式，界定施工缝对RC剪力墙抗震性能的影响程度与范围，提出以试验结果和理论分析为依据的沿施工缝的抗滑移验算公式，并给出相应的实用抗震计算方法。

本项目以2018年汶川地震中发现的沿施工缝震害为出发点，以破坏较多的RC剪力墙构件为研究对象，通过试验研究、理论分析和数值计算相结合的手段，深入分析了施工缝对RC剪力墙抗震性能的影响。主要研究内容包括：①施工缝对RC剪力墙抗震性能影响的试验研究；②带施工缝RC剪力墙构件的塑性铰模型和等效塑性铰长度；③带施工缝RC剪力墙构件基于截面的剪切恢复力模型的建立；④施工缝的力学模型及在剪力墙构件数值模拟中的应用；⑤带施工缝RC剪力墙的抗滑移验算。. 首先优选试验方案，进行6片剪力墙构件的拟静力试验。分析试验数据，从试验现象、滞回曲线、耗能、承载力、延性、刚度及强度退化等各方面分析施工缝对构件抗震性能的影响。试验中重点量测了施工缝周围区域的变形，分析各变形分量的变化以及施工缝处混凝土结合面和穿过缝面钢筋两种组分在各种力的传递机制，建立施工缝的数学模型。该施工缝模型传力机制明确，便于在数值计算中应用，且可以考虑轴向力和弯矩的耦合，切向受力性能由试验加理论分析得到的施工缝周围塑性铰区基于截面的剪切本构来模拟，计算精度较高。施工缝模型的建立为使建立的结构模型与实际建成结构在较大程度上实现吻合提供理论支持。. 施工缝另一个主要影响表现在较早出现开裂并形成贯通主裂缝，使破坏区域集中，塑性铰区长度缩短。试验中针对此问题进行研究，最终结合理论分析，给出带缝RC剪力墙构件塑性铰区长度的确定方法。为基于性能的抗震设计提供依据。. 带施工缝RC剪力墙抗震设计的重点在于抗滑移验算。针对高规中给出的抗滑移验算公式进行校核。结合试验数据、计算数据和理论分析，给出可靠性较高的抗滑移验算公式。