土坯民居加固前后抗地震倒塌能力研究

Study on seismic collapse resistance of adobe dwellings before and after reinforcement

为了研究墙体两侧绑扎竹条加固后土坯民居的抗震性能,采用静力弹塑性推覆方法分析加固前后土坯墙体的承载力、变形能力,并利用动力弹塑性时程分析方法对加固前后单层土坯民居进行抗地震倒塌能力研究。数值分析表明:加固后土坯墙体的抗剪承载力从加固前的13.17kN增至17.75kN,增幅为34.7%;极限位移从加固前的3.8mm增至7.56mm,增幅为98.9%。加固后单层土坯民居倒塌时的顶点位移由加固前的100mm提高至167mm,增幅为67%,且在倒塌时竹条未达到破坏强度。加固前单层土坯民居能够满足7度大震(0.22g)不倒的设防目标,但在遭受0.26g地震作用时会发生倒塌;而加固后土坯民居在遭受0.4g地震作用时没有倒塌,在遭受0.45g地震作用时会发生倒塌。两侧的竹条提高了墙体的抗剪承载力,形成的竹条笼有效地约束土坯墙体,延缓土坯墙体开裂后刚度下降速度,增强整体结构抵抗变形能力,使加固后单层土坯民居的抗地震倒塌能力明显提高。

In order to study the seismic performance of adobe dwellings strengthened with bamboo strips on both sides of the wall,the static elastic-plastic pushover method is used to analyze the bearing capacity and deformation capacity of adobe walls before and after reinforcement,and the dynamic elastic-plastic time history analysis method is used to study the seismic collapse resistance of single-layer adobe dwellings before and after reinforcement.The numerical analysis shows that the shear capacity of reinforced adobe wall increase from 13.17 kN to 17.75 kN,an increase of 34.7%;the ultimate displacement increase from 3.8 mm to 7.56 mm,with an increase of 98.9%.After reinforcement,the displacement of the top of the single-layer adobe dwellings increased from 100 mm to 167 mm,an increase of 67%,and the bamboo strips do not reach the failure strength.The results show that the single-layer adobe dwellings before reinforcement could meet the fortification target of 7 degree earthquake(0.22 g),but it would collapse under 0.26 g earthquake action.The reinforced adobe dwellings do not collapse under 0.4 g earthquake action,but collapsed under 0.45 g earthquake.The bamboo strips on both sides of the wall improve the shear bearing capacity of the wall,and the formed bamboo bar cage can effectively restrain the adobe wall,delay the stiffness decline speed of the adobe wall after cracking,enhance the overall structure resistance to deformation,and significantly improve the earthquake collapse resistance of the reinforced single-layer adobe dwellings.