CFRP拉索在横向风荷载作用下的振动特性  

Dynamic characteristics of CFRP cables under lateral wind load

作　　者：谢旭[1] 张鹤[1] 朱越峰[1] 苟昌焕[2] 

机构地区：[1]浙江大学土木工程学系,浙江杭州310027 [2]中华大学土木工程学系,台湾新竹

出　　处：《浙江大学学报（工学版）》2008年第1期145-151,共7页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50578141)

摘　　要：为了分析在横向风荷载作用下碳纤维拉索(CFRP拉索)的振动特性,按等参元方法提出了考虑风荷载影响的柔性拉索非线性振动方程.以跨度为1400 m的斜拉桥设计方案为对象,分析了CFRP拉索在横向风荷载作用下的变形特性及其在不同风速条件下的自振频率和振型阻尼比变化规律,并与在同样条件下的钢索进行了对比.分析结果表明,在横向风荷载作用下,CFRP拉索的横向变形与在同等条件下设计的钢索等同;CFRP拉索的结构振动特性与普通钢索有显著的差异;横向风荷载虽然对钢索和CFRP拉索的自振频率影响不大,但对振型的影响比较显著;随着横向风速的提高,按复数特征值算法得到的CFRP拉索振型阻尼比有增加和减少两种变化趋势,而且在低风速条件下出现负阻尼比的振型.A nonlinear motion equation of cables accounting for the action of lateral wind load using iso-parametric element method was proposed to analyze the dynamic characteristics of carbon fiber reinforced plas- tic （CFRP） cables. Taking the cables of a cable-stayed bridge with a span of 1 400 m as object, the deformation properties under lateral wind load, frequencies and modal damping ratios with different wind velocities of the CFRP cables were compared with those of steel cables. Results show that the out-of-plane deformation of CFRP cables under lateral wind load is identical to that of the corresponding steel cables. Remarkable difference exists between the characteristics of CFRP and steel cables. The lateral wind load has little effect on the frequencies of CFRP and steel cables but significantly affects their mode shapes. As wind velocity increases, the cable＇s damping ratios obtained with complex eigenvalue method may increase or decrease, and negative damping ratios of CFRP cables were observed under low-velocity wind load.

关 键 词：斜拉索 风振 风载 振动特性 碳纤维拉索 

分 类 号：U448.27[建筑科学—桥梁与隧道工程]