桥梁拉索用CFRP线材阻尼特性试验研究和理论分析

EXPERIMENTAL AND THEORETICAL STUDIES ON THE DAMPING PROPERTIES OF CFRP WIRES USED IN BRIDGE CABLES

为获得用于桥梁的CFRP拉索的阻尼特性,用自由衰减振动试验方法测试了CFRP线材(CFRP丝)和高强度钢丝的阻尼值,根据应变能比例阻尼理论分析了其弯曲变形的能量损失系数。通过不同振动频率条件下的测试结果比较了CFRP丝和钢丝的阻尼特性及其与振幅之间的相关性。结果表明,两种材料的振动阻尼均随应变幅值的增加而单调增加,但两者的变化趋势有差异。在同一应变幅值条件下,CFRP丝的实测阻尼值比高强钢丝的小。高强钢丝的能量损失系数与振幅无关,验证了能量损失理论对高强钢丝材料的阻尼计算的适用性。但CFRP丝的能量损失系数实测结果较离散,且与振幅有一定相关性,在特定振幅范围内可采用能量损失理论计算CFRP丝的阻尼。

In order to evaluate the damping of carbon fiber reinforced plastic(CFRP) cables used in bridges, the free vibration of a CFRP wire has been tested, and the loss factor of bending strain energy has been discussed according to the energy-based evaluation of modal damping. By performing a test at different frequency conditions, the relationship between the damping and the vibration amplitude of CFRP and steel wires has been studied. According to the experimental results, the damping increases with the vibration amplitude. However, the variation patterns of the damping-vibration amplitude curves are observed to be different between CFRP and steel wires. The damping of the CFRP wire is smaller than that of the steel wire while the strain amplitude is similar. The energy-based evaluation is proved to be efficient for the calculation of damping of steel wire, because the energy loss factor is found to be independent of the vibration amplitude of steel wire. For CFRP wire, the tested energy loss factors are not as regular as those of the steel wire. However, the energy-based evaluation could also be used to estimate the damping of CFRP wire while the vibration amplitude is distributed in a certain range.