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

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. © 2021, Editorial Office of Journal of Building Structures. All right reserved.