冻融条件下四氟滑板橡胶支座受压性能研究

Compression tests of PTFE slide rubber bearings under freeze-thaw cycle condition

为了研究四氟滑板橡胶支座经过冻融循环后的承载力变化情况,采用标准冻融试验箱对氯丁橡胶支座进行25,50,75,100,150次的冻融循环处理并进行轴心受压试验,研究其在不同冻融循环次数的承载力、极限抗压强度、竖向刚度、弹性模量等各项性能指标的变化,并与标准试件进行对比分析。结果表明经过冻融循环处理的氯丁橡胶支座更容易发生脆性破坏,且钢板外露、裂缝等破坏现象比标准试件更严重。随着冻融循环次数的增加,冻融程度的加深,氯丁橡胶支座极限承载力、极限抗压强度都逐渐降低;采用最小二乘法得出50年抗压强度的衰减曲线和衰减公式,其变化趋势基本符合指数函数规律。冻融循环后的公路桥梁板式氯丁橡胶支座的各项力学性能指标显著降低,因此应严格控制公路桥梁板式氯丁橡胶支座的温度适用范围,并建议提高其最低适用温度,在寒冷地区尽量采用天然橡胶支座。

In order to study the change of the mechanical properties during the life of the PTFE slide rubber bearings under freeze-thaw cycle condition, the plain chloroprene rubber bearings were processed 25, 50, 75, 100 and 150 times by freeze-thaw cycle in the standard freeze-thaw chamber, then the axial compression tests were carried. The changes of the performance indicators in the bearing capacity, the ultimate compressive strength, and vertical stiffness under different freeze-thaw cycles were analyzed comparatively. The results show that the PTFE slide rubber bearings more prone to brittle failure which after the freeze-thaw cycle, and the steel plate exposing, cracks and other damage phenomena are more serious than the standard specimen. With the increasing in the number of freeze-thaw cycle, the ultimate bearing capacity and ultimate compressive strength of the PTFE slide rubber bearings decrease. The attenuation formula and decay curve in 50 years of ultimate compressive strength is analyzed by least square method. The trend of change is in line with the exponential function. The mechanical properties of PTFE slide rubber bearings significantly decreased under freeze-thaw cycle condition. Therefore, the temperature ranges of PTFE slide rubber bearings should be controlled strictly; its minimum applicable temperature should be proposed to increase, and the natural rubber bearings should be used as much as possible in cold regions.