Damping characteristics of PC partial cable-stayed bridge

Taking a PC partial cable-stayed bridge with tower beam consolidation and pier beam separation system as an example,the damping characteristics of such structures was investigated in bridge vibration test.Based on non-orthogonal damping theory,the relationship between component damping and modal damping ratio was studied,and the assumption that the modal damping ratio can be obtained by superposition of component damping under small damping condition was verified.The characteristics of damping ratio which was calculated by strain energy proportional damping theory was discussed,and the component damping ratio was talked over by comparison of experimental and theoretical results.The results show that the damping ratios of vertical bending mode and torsional mode are about 1%,which is less than that of ordinary PC continuous beam bridge.The damping ratio can be obtained by linear superposition of component damping according to non-orthogonal damping theory.It also can be approximately estimated with strain energy proportional damping theory,while the material damping ratios of PC beam,concrete pier and tower and steel cable are around 1.0%,1.2%,0.1% and 4.0% respectively.