计入转动变形影响的砌体结构抗震设计理论研究

In recent years, earthquake activity tends to be active, and the seismic safety of masonry structures has become a growing concern. Seismic damage investigation shows that the rotation deformation is an objective existence in the process of the failure of the masonry walls. The test shows that the rotational deformation has a significant impact on the lateral stiffness and ultimate bearing capacity of the masonry wall. This project intends to investigate the masonry structure seismic design theory affected by the rotational deformation. By using a combination of experimental, numerical simulation and theoretical analysis methods, the following key problems will be solved: (1) through model test, the effects of different elevation shape and different external force direction affect the masonry wall deformation mechanism will be researched; (2) a masonry wall lateral stiffness model will be established which fully reflect the elastic-plastic deformation mechanism (shear deformation, bending deformation, rotational deformation), and a improvement interlayer stiffness calculation method will be proposed which can reflect external force direction; (3) masonry shear distribution envelope method will be proposed, and masonry structure seismic design theory included in the rotational deformation will be established. The project will turn deformation included in the masonry wall of equivalent lateral stiffness; and conform to the deformation mechanism of the masonry wall in the whole process, especially in the elastic-plastic stage and the failure stage. So that the distribution of the seismic action of the masonry structure under the earthquake is in accordance with the practice. It has important scientific significance to realize the seismic fortification goal of masonry structure with no collapsing with strong earthquake.

近年来地震活动趋于活跃，砌体结构抗震安全成为人们日益关注的问题。震害调研表明，转动变形在砌体结构破坏过程中是客观存在的；试验表明，转动变形对砌体墙抗侧刚度、承载力等产生明显影响。本项目拟开展计入转动变形影响的砌体结构抗震设计理论研究，采用试验、数值模拟与理论分析相结合的方法，重点解决以下关键问题：（1）通过模型试验，研究不同立面形状、外力作用方向等因素影响的砌体墙变形机制；（2）建立全面反映弹塑性阶段变形机制（剪切变形、弯曲变形、转动变形）的砌体墙等效抗侧刚度模型，提出考虑外力作用方向的改进层间刚度串并联计算方法；（3）提出砌体结构剪力分配包络法，建立计入转动变形的砌体结构抗震设计理论。本项目将转动变形计入砌体墙抗侧刚度，符合砌体墙在受力全过程尤其是弹塑性阶段的变形机制，使得大震下砌体结构层间地震作用分配规律符合实际，对于更好地实现砌体结构“大震不倒”的抗震设防目标具有重要科学意义。

转动变形是砌体房屋中砌体墙在水平荷载作用下的一种变形现象，本项目考虑转动变形对砌体墙等效抗侧刚度、水平承载力的影响，开展了计入转动变形影响的砌体结构抗震设计理论研究，主要研究工作如下：（1）复杂立面形状砌体墙、门窗间砌体墙、双肢砌体墙抗震性能试验，分析了不同立面形状、不同荷载作用方向等因素引起的转动变形机理和破坏模式。（2）结合试验数据，采用理论分析、有限元模拟与试验数据拟合相结合的方法提出了3种计入转动变形影响的砌体墙等效抗侧刚度模型，与传统弹性刚度算法相比，转动变形影响下砌体墙刚度下降，高宽比越大，等效刚度下降越多，分担的地震作用越小。（3）基于非对称立面砌体墙节点区斜裂缝破坏现象，提出了2种非对称立面砌体墙沿节点斜裂缝转动破坏的水平承载力计算方法，与砌体墙实际破坏模式有着较好的对应性，较窗间墙斜裂缝破坏有着更为明确的物理意义。（4）提出了砌体房屋抗震设计的包络设计方法和主要步骤，构造算例对比分析了现行算法和本项目算法在砌体墙层间地震作用分配规律方面的差异。本项目研究工作为进一步完善砌体结构抗震设计理论、查找现行设计方法下可能存在的抗震薄弱环节提供了新的思路，有助于提高中震大震下砌体结构的抗震能力。