偏压荷载与海水干湿作用后钢筋混凝土柱滞回性能及微观结构试验研究

发布时间：2019-06-20 19:15

【摘要】：为研究沿海地区在役钢筋混凝土(RC)柱的滞回性能及混凝土的微观结构和氯离子含量,对不同前期偏压荷载(0、0.20、0.35倍峰值偏压荷载)作用下,经历100次海水浸泡与大气环境干湿循环后的RC柱进行低周反复加载试验,并对混凝土的微观结构和氯离子含量进行量测。结果表明:前期偏压荷载作用后RC柱的滞回曲线呈现出明显的不对称。当水平反复加载与前期偏压荷载产生的截面应力分布同向时,其峰值荷载、延性及耗能能力随着前期偏压荷载的增加而降低;当前期偏压荷载为0.35倍柱峰值偏压荷载时,其峰值荷载、延性及耗能能力较前期未受偏压柱试件的降幅较大,分别达到26.1%、22.0%和44.6%;当水平反复加载与前期偏压荷载产生的截面应力分布反向时,各参数变化无明显规律。另外,在距受拉区混凝土表面20 mm和40 mm深度处,前期受偏压柱试件的氯离子含量分别是未受偏压柱试件的4.7倍和1.5倍以上,同时前期受偏压柱试件的受拉区混凝土裂缝数量和宽度明显多于未受偏压柱试件。按照现行混凝土结构设计规范计算截面受弯承载力,由于前期偏压荷载造成的滞回曲线不对称,水平反复荷载与前期偏压荷载产生的截面应力分布同向时,试验值小于计算值。由此可见,前期偏压荷载对RC柱的滞回性能劣化、受拉混凝土的氯离子含量和微观结构均有较大影响,进而缩短结构使用寿命。
[Abstract]:In order to study the hysteretic properties of reinforced concrete (RC) columns in coastal areas and the microstructure and chloride content of concrete, the low cycle repeated loading tests of RC columns after 100 times of seawater immersion and dry and wet cycles in atmospheric environment were carried out under different bias loading (0, 0.20, 0.35 times peak bias load), and the microstructure and chloride content of concrete were measured. The results show that the hysteretic curve of RC columns under eccentric loading in the early stage is obviously asymmetrical. When the stress distribution of the section produced by horizontal repeated loading is in the same direction as that produced by the previous bias load, the peak load, ductility and energy dissipation capacity decrease with the increase of the bias load in the early stage, and the peak load, ductility and energy dissipation capacity decrease by 26.1%, 22.0% and 44.6%, respectively, when the initial bias load is 0.35 times the peak eccentric load of the column, and the energy dissipation capacity is 22.0%, 22.0% and 44.6%, respectively, when the peak load is 0.35 times the peak bias load of the column, and the peak load, ductility and energy dissipation capacity are 22.0% and 44.6%, respectively. When the stress distribution of the section produced by horizontal repeated loading is reverse from that caused by bias load in the previous stage, there is no obvious change of each parameter. In addition, at the depth of 20 mm and 40 mm from the surface of concrete in the tensile zone, the chloride ion content of the specimen under eccentric compression is 4.7 times and 1.5 times as much as that of the specimen without eccentric compression, respectively. At the same time, the number and width of concrete cracks in the tensile zone of the specimen subjected to eccentric compression are obviously more than those of the specimen without eccentric compression. According to the current design code of concrete structure, the bending bearing capacity of the section is calculated. Due to the asymmetry of the hysteretic curve caused by the bias load in the early stage, the experimental value is less than the calculated value when the stress distribution of the section caused by the horizontal cyclic load and the early bias load is in the same direction. It can be seen that the early bias load has a great influence on the hysteretic performance of RC columns, the chloride ion content and microstructure of tensile concrete, and then shortens the service life of the structure.
【作者单位】：北京航空航天大学土木工程系;华南理工大学亚热带建筑科学国家重点实验室;
【基金】：国家自然科学基金项目(51078015) 亚热带建筑科学国家重点实验室重点项目(2013KA03)
【分类号】：TU375.3

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