聚丙烯网水泥砂浆面层加固砖砌体农房振动台试验研究

Shaking table test on brick masonry farmhouse strengthened by polypropylene grid cement mortar coating

为提高砖砌体农房的抗震性能,提出聚丙烯网水泥砂浆面层加固方法,选取陕西省蓝田县典型的单层、双开间砖砌体农房进行抗震加固,并对加固模型进行地震模拟振动台试验;选取El Centro波、Taft波和人工波作为输入地震波,获得并分析加固模型的地震破坏特征、动力特性和加速度、位移、扭转角、底部剪力等动力响应,以及底部剪力-山墙尖相对位移滞回曲线和累积耗能。结果表明:随着输入地震波峰值加速度的增大,加固模型的自振频率下降、阻尼比增大、加速度放大系数减小;加固模型山墙屋脊纵剖面的侧移最大,8度多遇地震、设防地震和罕遇地震时的最大侧移角分别为1/5 439、1/2 195和1/522,当输入地震波峰值加速度达到1.0g时,最大侧移角为1/112,山墙中部出现较为明显的外闪;加固模型在地震作用下发生了扭转,水平扭转角最大达到0.003 7 rad。聚丙烯网水泥砂浆面层加固方法能够显著提升砖砌体农房在地震作用下的变形能力和耗能能力,使其满足抗震设防要求,并且加固成本较低,适用于高烈度区的砖砌体农房抗震加固。

In order to improve the seismic performance of brick masonry farmhouse,the strengthening method of polypropylene grid cement mortar coating was proposed.A typical single-story and double-bay brick masonry farmhouses in Lantian County,Shaanxi Province was selected for seismic strengthening,and the shaking table tests were carried out on the strengthened model.El Centro wave,Taft wave and artificial wave were chosen as input earthquake waves.The seismic failure pattern,dynamic characteristics and dynamic response,such as acceleration,displacement,torsion,base shear,as well as hysteretic curves and cumulative dissipation were obtained and analyzed.The results show that,with the peak acceleration of the input earthquake waves,the natural frequency and acceleration amplification factor of the strengthened model decrease,and the damping ratio increase.The maximum inter-story drift occurs at the longitudinal section of gable ridge,and the maximum inter-story drift ratios of the strengthened model were 1/5439,1/2195 and 1/522 under eight degree frequent earthquake,design basis earthquake and maximum considered earthquake,respectively.When the peak acceleration of the input earthquake waves reached 1.0g,the maximum inter-story drift ratio was 1/112,and the obvious convexity occurred at the middle of the gable.The strengthened model was twisted under the earthquake,and the maximum horizontal torsion angle reached 0.0037rad.The strengthening method of polypropylene grid cement mortar coating can not only improve the deformation capacity and energy dissipation capacity of the brick masonry farmhouse significantly,but also have the low strengthening cost.It can be popularized and applied in the seismic strengthening of brick masonry farmhouses in the high seismic intensity areas.