百米H型索塔防开裂控制技术研究

发布时间：2018-04-29 16:50

本文选题：斜拉桥 + 塔柱　；参考：《铁道工程学报》2017年01期

【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。
[Abstract]:The purpose of this study is: when the concrete section of the main tower is poured, the hydration causes the temperature of concrete to rise, and with time, the temperature of concrete will decrease gradually, but the temperature of each position of the structure will drop unevenly and form the relative temperature difference. Under the effect of temperature difference, shrinkage and creep, the problem of early cracking is more prominent because of the constraint of the front segment. At the same time, the concrete at the bottom of the tower column will cause a lot of bending moment under the action of self-weight and external load, which makes the concrete at the bottom of the tower under compression and tension on the other side. If the treatment is not proper, cracks may appear. Yujiang double-line bridge adopts 100 m tall vase-shaped cable tower with huge structure size and high construction precision. Taking the construction of the cable tower of Yujiang Bridge as an example, based on the finite element software ANSYS to model and calculate the internal force of the structure, the first section of the main tower is selected as the representative segment to carry out the temperature and thermal analysis and the structural analysis. Then the main tower construction process is divided into 20 simulation calculation conditions, and the stress distribution characteristics of the structure under different working conditions are analyzed. According to the analysis results of the early hydration heat and the late cable tower force, The concrete measures against cracking of 100 m H type cable tower are put forward, which can provide reference for the construction of similar projects. Conclusion: (1) the early hydration heat effect of the first section of the main tower is analyzed by using the finite element software, and the formula for calculating the temperature difference deformation is derived, which is in agreement with the results of the finite element stress calculation. It is also put forward that the cooling control measures of concrete with ice cubes are as follows: (1) the design position of the lower tower column is equipped with a balance pull rod, and 2 balance rods are set in the middle tower design position. The above measures can effectively improve the stress condition of the structure. The comparison between the calculated values and the measured values at the key section points shows that the stress results of the finite element analysis of the column stress are in good agreement with the stress values measured in practice. The research results can provide reference for the construction of anti-cracking control of 100 m H cable tower.
【作者单位】：山西大学;中铁三局集团有限公司;
【分类号】：U445.57

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