冻融条件下GFRP隔震支座力学性能试验研究

Experimental study on mechanical properties of GFRP isolation bearing under freeze-thaw condition

冻融循环是影响寒冷地区玻璃纤维增强复合材料(GFRP)隔震支座性能变化的主要因素。为了研究其影响,对12个GFRP隔震支座分别开展水冻水融试验,采用标准冻融试验箱模拟低温气候变化,对GFRP橡胶支座进行冻融循环处理25、50、75次,并对其进行刚度性能试验,采用与标准试件进行对比分析的方法,研究试验前后支座性能的变化规律。结果表明:冻融后GFRP隔震支座的水平刚度比常温下的要高;经历过冻融试验的GFRP隔震支座,其水平刚度随着测试时间的增长而减小。同时,当压应力不变时,水平刚度随着剪应变增加而下降;当剪应变不变时,水平刚度随着压应力增大而下降,且能够承受极限水平刚度的压应力和剪应变越来越小。无橡胶层保护的GFRP隔震支座的水平刚度变化幅度小于有橡胶层保护的GFRP隔震支座的水平刚度变化幅度,极限水平刚度的压应力和剪应变更小。采用最小二乘法对其水平刚度变化进行分析并给出衰减曲线和衰减函数,水平刚度的变化趋势基本符合二次多项式规律。

Water freezing and thawing are the main factors affecting the performance of fiber reinforced polymer(GFRP) isolation bearings in cold regions. The water freeze-thaw test was carried out on twelve GFRP isolation bearings. The chamber for standard freeze-thaw test was used to simulate the low-temperature climate change. The GFRP rubber bearings were treated with freeze-thaw cycles of 25, 50 and 75 times. The stiffness and performance tests were carried out. The change rule of bearing performance before and after the freeze-thaw cycles was studied by stiffness test and comparison analysis with the control specimen. The results show that the horizontal stiffness of GFRP isolation bearing after freeze-thaw is higher than that at normal temperature, and the horizontal stiffness decreases with the increase of test duration. At the same time, when the compressive stress is constant, the horizontal stiffness decreases with the increase of shear strain. When the shear strain is constant, the horizontal stiffness decreases with the increase of compressive stress, small compressive stress and shear strain that can withstand the ultimate level stiffness. The variation range of horizontal stiffness of GFRP isolation bearing without rubber layer protection is smaller than that of GFRP isolation bearing with rubber layer protection, and the compressive stress and shear strain of ultimate horizontal stiffness are smaller than those of GFRP isolation bearing with rubber layer protection. The variation of horizontal stiffness was analyzed by least square method and the attenuation curve and attenuation function were given. The variation trend of horizontal stiffness basically agrees with the law of quadratic polynomial.