用增设钢筋混凝土墙提高砌体结构抗震性能的试验研究

Experimental study on seismic behavior of masonry structure with post-installed reinforced concrete walls

目前大量既有多层砌体结构住宅面临增设电梯、成套改造等功能性改造的需求,利用功能性改造时后加的混凝土墙提高既有多层砌体结构的抗震性能是一种有益的探索。文中提出了三种后加混凝土墙与砌体墙的连接方式,并进行了7个后加混凝土-砌体组合墙体试件及其对比试件的低周反复加载试验,研究了其破坏模式、滞回性能、承载能力、变形能力、耗能与延性等。试验结果表明:三种连接方式均能有效保证后加混凝土墙与砌体墙的协同工作,其中植筋连接方式最为简便实用;后加混凝土墙不对称布置时,正、反两个方向的刚度退化过程不同但承载能力和变形能力无明显差异;增设混凝土墙后砌体墙的承载能力、变形和耗能能力大幅度提升,刚度退化明显改善;组合墙体中后加混凝土墙和砌体墙的抗剪能力均能充分发挥。基于黏性界面模拟砂浆层的分离式三维实体有限元分析方法能够较好地模拟组合墙体试件的骨架曲线和破坏形态。根据试验结论提出的受剪承载力计算公式与试验结果吻合良好。

So far, there are a lot of existing multi-storey masonry residential buildings whose functions shall be upgraded by adding elevators, complete housing transformations and so on, while it shall be a beneficial exploration to improve the seismic behavior of masonry sturctures by the post-installed concrete walls. Three types of connections between post- installed concrete wall and masonry wall were proposed in this study, and cyclic loading tests were conducted on seven specimens including composite walls and reference walls. Their failure mode, hysteretic behavior, bearing capacity, deformation capacity, energy dissipation and ductility were investigated. Test results show that the proposed three types of connections are all capable of ensuring the cooperative work between the post-installed concrete wall and masonry wall, and the steel bar-embedding connection shall be the most convenient and practical. When the post-installed concrete wall is arranged asymmetrically, the stiffness degradations in the positive and negative directions are different, but the bearing capacity and deformation capacity in the two directions are similar. The bearing capacity, deformation capacity, energy dissipation and stiffness degradation of masonry wall can be greatly improved once concrete wall is added, and shear capacities of concrete and masonry walls can be fully used in the composite wall. In addition, 3D finite element methods based on cohesive interfacial model with contact property can be used very well to simulate the skeleton curve and failure mode of composite walls. A calculation formula for the shear capacity of composite wall was proposed, and its predictions agree well with the experimental results.