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针对砖砌体结构抗震性能差的问题,提出了采用竖向后张预应力对砖砌体结构进行抗震加固的方法,即沿被加固墙体均匀布置预应力筋并施加竖向预应力,使墙体均匀受压,从而改善砌体墙体在地震作用下的破坏形态,提高其受剪承载力和抗震耗能能力。为验证该项方法的加固效果,对加固无筋砖墙体及其对比墙体进行了拟静力试验,试件中有5片为整截面墙体,4片为开洞墙体,研究对比分析了未加固墙体与后张预应力加固墙体的破坏形态和受力特点。结果表明,后张预应力加固可以显著提高墙体的受剪承载力和变形能力,抗震耗能能力显著增强。其中整截面墙体加固后,其承载力和延性的提高幅度较开洞墙体更为显著。但预应力施加不宜过大,当预应力与竖向荷载的组合作用轴压比超过临界点时,延性会有一定程度下降。同时,后张预应力加固还可以降低无筋砖砌墙体的刚度退化速率,提高无筋砌体墙的开裂后刚度,这对改善墙体在强震作用下的受力性能有重要作用。该加固方法基本不改变墙体的弹性抗侧刚度,加固后墙体的质量也基本没有增加,是一种行之有效的抗震加固方法。
Aiming at the problem of poor seismic performance of brick masonry structures, a method of seismic retrofit of brick masonry structures with vertical post-tensioned prestress is proposed, in which prestressed tendons are uniformly arranged along the wall to be reinforced and vertical prestressing is applied The wall is evenly pressed, so as to improve the failure mode of the masonry wall under the action of the earthquake and improve its shear capacity and seismic energy dissipation capacity. In order to verify the reinforcement effect of this method, the quasi-static test was conducted on the reinforced non-stiffened brick wall and its contrast wall. Five of the specimens were full-wall cross-sections and four were open-hole walls. The failure mode and force characteristics of un-reinforced and post-tensioned prestressed reinforced walls are analyzed. The results show that the post-tensioning prestressed reinforcement can significantly increase the shear capacity and deformation capacity of the wall, and the seismic energy dissipation capacity is significantly enhanced. The reinforcement of the whole section of the wall, the bearing capacity and ductility increased more significantly than the opening of the wall. However, the prestressing should not be applied too much. When the axial compression ratio of prestressed and vertical loads exceeds the critical point, the ductility will decrease to a certain degree. At the same time, the post-tensioned prestress reinforcement can also reduce the stiffness degradation rate of the non-reinforced brick wall and improve the post-cracking stiffness of the non-reinforced brick wall, which plays an important role in improving the stress performance of the wall under strong earthquake. The reinforcement method basically does not change the elasticity of the wall stiffness of the wall, the quality of the wall after the reinforcement has basically no increase, is an effective seismic strengthening method.