预制装配式ECC小剪跨比剪力墙抗震性能研究

Taking advantage of the characteristic of ECC which shows prominent tensile ductility and toughness, a new type of precast Engineered Cementitous Composites (ECC) shear wall with low shear span-to-depth ratio is proposed based on the result of the previous studies and development of industrialization of construction. The theoretical derivation, numerical analysis and experimental study are intended to be used to study on the seismic behavior and design method of precast ECC shear wall with low shear span-to-depth ratio from the construction level, the member level and the structural level. On the construction level, the research results of horizontal connections for precast concrete shear walls are summarized and analyzed first, the mechanic performance and construction details of hybrid connections will be studied through numerical modeling and calculation. On the member level, through quasi-static experiments and numerical simulation, the influence of key parameters on the hysteretic behavior of squat shear wall will be studied, and the mechanic model for the hysteretic behavior of squat shear wall will be established; with the structural topology optimization technique, nonlinear strut-and-tie model with better visualization of the internal force distribution and the force transfer mechanism of the squat wall under combined axial and shear loads will be developed. On the structural level, the relationship of performance index, performance level and ductility demands will be studied first, and the connections between axial load ratio and ductility, confining stirrups of boundary element of wall will be established, and then the performance-based design method for precast ECC shear wall with low shear span-to-depth ratio and design suggestions will be provided. The research achievement could enhance the foundation of the application of ECC in shear walls and be helpful in the establishment of related code.

在前期研究基础上，利用超高韧性水泥基复合材料(ECC)的高延性和高韧性，提出了一种预制装配式ECC小剪跨比剪力墙结构。拟通过理论分析-数值模拟-模型试验相结合的方法，从“接缝构造、构件性能和结构设计”三层次对其抗震性能与设计方法开展研究。构造层次：通过数值模拟和计算，建立接缝处竖向钢筋混合连接构造设计细则。构件层次：通过拟静力试验与数值模拟，研究关键参数对小剪跨比剪力墙抗震性能的影响规律，构建反映其滞回性能的力学模型，通过拓扑优化分析，掌握小剪跨比剪力墙的剪力传递机理，构建拉压杆模型，确定其关键参数的取值。结构层次：确定小剪跨比剪力墙的性能指标、性能水平与延性需求之间的关系，建立装配式ECC小剪跨比剪力墙延性与端部约束箍筋数量和轴压比之间的关系；研究基于性能的装配式ECC小剪跨比剪力墙的抗震设计方法。项目研究成果将为ECC在剪力墙结构中的应用及相关规范的编制提供基础。

采用试验研究、理论分析及数值模拟相结合的方法，对小剪跨比钢筋混凝土、装配式ECC剪力墙、装配式ECC连梁联肢剪力墙结构抗震性能开展了研究，为剪力墙结构的设计提供了理论基础及技术支撑。.对转换层结构上部邻近区域内剪力墙底部存在的剪力集中效应进行了模拟分析和研究，定义了剪应力不均匀系数与剪力集中放大系数，提出了剪力集中放大系数与内外墙转角之间关系的计算公式。通过对6片小剪跨比剪力墙在高轴压力及反复水平荷载作用下进行试验，对不同轴压比下小剪跨比剪力墙的抗震性能与剪力传递机理。考虑剪力墙构件腹板双向配筋的特点及应变相容条件，提出了等效斜向腹筋桁架-拱模型，提出了一种新的小剪跨比剪力墙受剪承载力和剪切刚度计算方法。.采用针对ECC材料特性，根据能量等价原理推导了损伤因子计算公式，开展了关于ECC小剪跨比构件试验，建立相应的数值分析模型和性能指标，变化参数包括轴压比、剪跨比、边缘约束构件配箍率等，从破坏形态、荷载位移曲线、延性等方面将数值结果与试验数据进行了对比，验证了塑性损伤模型的准确性。结果表明ECC能有效控制裂缝开展，延缓钢筋屈服；相比RC构件，ECC构件具有更高的受剪承载力、更好的延性和耗能能力。对ECC装配式小剪跨比剪力墙进行了有限元模拟，结果表明ECC可以有效增强小剪跨比剪力墙的位移延性，显著提升此类构件的抗震性能。基于修正压力场理论，提出了适用于ECC剪力墙的受剪承载力计算公式。.进行了7个小剪跨比预制与现浇对角斜筋ECC连梁和1个普通配筋ECC连梁抗震性能试验，相对于PVA纤维，采用PE纤维作为基体材料可以提高连梁的强度、刚度、延性及耗能能力，减小对角斜筋用量，利于装配化施工。提出了对角斜筋ECC连梁剪切铰恢复力模型。以FEMA P-58的建筑结构抗震性能评估流程为框架，对剪力墙结构分别采用普通配筋混凝土连梁、对角斜筋混凝土连梁以及对角斜筋ECC连梁的三栋结构进行震后可修复性量化评估，提出了对角斜筋ECC连梁基于震后可修复的设计方法。