摘要
由于超长桩基础大跨预应力混凝土斜拉桥结构在竖向表现出大尺度的特征,为给此类桥施工控制提供依据,以越南某(150+350+150)m双塔双索面预应力混凝土斜拉桥(最大桩长116m)为背景,采用MIDAS Civil软件建立全桥空间有限元模型,计算结构稳定安全系数,并分析桩长变化对结构稳定性和动力特性的影响程度及其规律。结果表明:桩长的增加引起桥梁结构竖向尺度的增大,降低了结构施工过程中的稳定性,主梁稳定性对桩长变化在边跨合龙前表现得比较敏感,在边跨合龙前应重视结构竖向尺度变化带来的稳定性问题;最低稳定安全系数(KL=6.5)出现在桥面铺装过程中,须引起施工重视,但该桥施工过程中稳定性仍满足规范要求(KL>4);随着桩长增加,结构基本频率降低,振型形状有所改变,施工控制中须随时关注结构动力特性的不利变化。
The long span prestressed concrete(PC)cable-stayed bridge structure with super long piles assumes the characteristic of large scale in the vertical direction of the structure.To provide the basis for the construction control of the structures of the similar kind,a PC cable-stayed bridge(the longest pile of the bridge being 116 m)with double pylons,double cable planes and with span arrangement(150+350+150)m in Vietnam was cited as an example and the spatial finite element model for the whole bridge of the bridge was established,using the software MIDAS Civil.The structural stability safety coefficients of the bridge were calculated and the degrees and law of influences of the pile length changing on the structural stability and dynamic characteristics were analyzed.The results show that the increase of the pile length increases the vertical scale of the bridge and decreases the stability of the bridge in the process of construction.The stability of the main girder of the bridge is sensitive to the pile length changing before the closure of the side span and before the closure of the span,attention should be paid to the stability problem caused by the vertical scale changing.The minimum stability safety coefficient(KL =6.5)appears in the deck pavement,to which attention should be paid,however,the stability of the bridge in the construction process can still satisfy the requirement(KL >4)in the specification.With the in crease of the pile length,the base frequencies of the bridge decrease,the shapes of the vibration modes change to some extent and in the construction,attention should be also paid to the adverse changing of the dynamic characteristics of the bridge from time to time.
出处
《桥梁建设》
EI
CSCD
北大核心
2016年第2期36-41,共6页
Bridge Construction
基金
交通运输部科技项目(2010-353-333-130)~~
关键词
斜拉桥动力特性
预应力混凝土结构
超长桩基
大跨径
有限元法
施工控制
稳定安全系数
cable-stayed bridge
prestressed concrete structure
super long pile
long span
finite element method
construction control
stability safety coefficient
dynamic characteristic
