摘要
研究目的:主塔混凝土节段浇筑时,水化作用引起混凝土温度上升,随着时间推移,混凝土温度会逐渐下降,但结构各个位置的温度下降速度不均匀,形成相对温差,由于受到前节段的约束,在温差、收缩、徐变效应作用下,早期开裂问题更为突出。同时,塔柱底部混凝土在自重、外荷载的作用下会引起很大的弯矩,使得塔柱底部混凝土一侧受压、另一侧受拉,如果处理不当则有可能出现裂缝。郁江双线特大桥采用100 m高花瓶状索塔,结构尺寸庞大,施工精度要求高。本文以郁江桥索塔施工为实例,基于有限元软件ANSYS建模计算结构内力,选择主塔第1节段作为代表节段进行温度热分析和结构分析,随后将主塔施工过程分为20个仿真计算工况,分析不同工况下结构的受力情况及应力分布特征,根据早期水化热和后期索塔受力两方面的分析结果,提出百米H型索塔防开裂的具体措施,为同类工程施工提供参考。研究结论:(1)利用有限元软件分析主塔第1节段的早期水化热效应,并推导出了温差变形计算公式,与有限元应力计算结果相吻合,并提出混凝土中加冰块的降温控制措施;(2)在下塔柱设计位置设置平衡拉杆,在中塔设计位置设置2根平衡杆,上述措施有效地改善了结构的受力状况,确保了结构受力安全;(3)关键截面位置测点计算值与实测值的对比结果表明,塔柱应力有限元分析的应力结果与实际测试的应力值变化趋势完全一致,吻合良好;(4)本研究成果可为百米H型索塔防开裂控制施工提供参考。
Research purposes： The temperature rise of concrete is caused by hydration thermal effect while concrete segment of the main tower is pouring. As the temperature of concrete is gradually decreased with time, descending speed of temperature in each position is uneven, the relative temperature difference is formed, because of constraints in anterior segment, under the action of temperature difference, shrinkage and creep, early age cracking is more prominent. Meanwhile, the bending moment on the bottom of tower column is very big under the action of weight and external load, the concrete is compressed on one side and is pulled on the other side, the crack may be caused by the misconduct of construction. The main tower of Yujiang Super Major Bridge has a vase - like shape and large dimension, which requires high survey precision. In this paper, taking construction of cable pylon of Yujiang Bridge as example, based on the element software ANSYS modeling to solve structure internal force calculation, the thermal analysis and structural analysis of the first segment are selected as example, twenty calculation cases are presented in construction ofcable pylon, force condition and stress distribution of different calculation cases are analyzed. The concrete measures in cracking prevention of 100 meter high H - type cable tower are proposed according to analysis results of the early hydration effect and later force condition of cable tower, to provide reference for similar projects. Research conclusions： （ 1 ） The paper analyzes the early hydration thermal effect of the first segment by finite element sofeware, the formula of temperature deformation is derived, calculations of the formula are in good agreement with results of finite element sofeware, adding ice to concrete is a cooling measure. （ 2 ） The tie rod of bottom columns is established in design position, the two balancing rods of middle tower columns are established in design position, the force condition of cable tower is effectively improved by the
作者
刘晋艳
胡国伟
LIU Jin -yan HU Guo - wei(Shanxi University, Taiyuan, Shanxi 030013, China China Railway No. 3 Engineering Group Co. Ltd, Taiyuan, Shanxi 030001, China)
出处
《铁道工程学报》
EI
北大核心
2017年第1期60-66,共7页
Journal of Railway Engineering Society
关键词
斜拉桥
塔柱
应力
防开裂控制
cable- stayed bridge
pylons
stress
anti- cracking control
