单肋斜撑钢管混凝土拱桥动力特性分析

Dynamic Characteristics Analysis of Single Rib Braces CFST Arch Bridge

单肋斜撑钢管混凝土拱桥是近年来出现的一种新型桥梁,以广梧高速双凤至平台段K111+495跨线桥为例,采用ANSYS有限元软件,对该桥的振动频率及振型进行了分析,讨论了拱肋抗压、抗弯刚度对其动力特性的影响,并就行人舒适性问题进行了探讨.结果表明:该桥面外刚度相对较小,在桥梁振动中首先出现拱肋面外对称侧弯,桥梁前10阶振型中有4阶为拱肋的面外振动;桥梁拱肋面外自振基频小于桥梁整体竖向自振基频,说明桥梁拱肋面外刚度与全桥竖向刚度相差较大;桥梁的扭转频率出现在第5阶,说明结构的抗扭刚度较大,容易满足刚度要求;改变拱肋抗压刚度对于桥梁各阶振型频率影响极小,而改变拱肋抗弯刚度则对各阶振型频率有一定的影响;但拱肋抗弯、抗压刚度的变化均不会影响该桥的振型;本桥的一阶竖向频率为2.111 Hz,舒适性指标不满足国际上CEB(1993),SIA(1989),"立体横断施设技术基准.同解说"(1979),对行人舒适性有一定的影响,值得注意.

The single rib braces CFST arch bridge is a new type of bridge in recent years, the dynamic characteristics of Guangzhou-Wuzhou expressway Shuangfeng to Pingtai Klll ＋495 flyover is analyzed by the common finite element method software-ANSYS,the effect of rigidities on its dynamic characteristics and pedestrian comfort are discussed. The results show that the bridge out-surface stiffness is small,the out-surface vibration of the arch rib appears first in bridge vibration and there are 4 steps of out-surface vibration in first 10 step; its vertical stiffness is more greater than its out-surface stiffness;the bridge＇s distorted frequency appeared the fifth step so that its torsion rigidity is great and easily meet demand;the change of compre;sive stiffness for concrete-filled steel tube have little influence to each vibration frequency,and the change of bending stiffness for concrete-filled steel tube have certain influence to each vibration frequency, but both do not change the bridge＇s vibration type; the bridge primary frequency is 2. 111 Hz, the index of pedestrian comfort not satisfy CEB（1993）, SIA （1989） ,＂stereo breaking cross facilities technology reference with explanation（1979）＂, so have definite influences on pedestrian comfort, it is worthy be highlighting.