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分析了混凝土结构温度场边界条件计算方法,以青海省海黄大桥H形混凝土桥塔为工程背景,计算了高原高寒地区四季典型气象条件下的桥塔温度场分布,对比了四季的桥塔表面温差和塔壁局部温差,确定了桥塔的最不利温度荷载,建立了桥塔整体有限元模型,分析了四季桥塔的偏位、竖向应力、横向应力和纵向应力等温度效应。分析结果表明:桥塔表面温差与桥塔局部温差均在冬季最大,最大值分别可达11.88℃、20.79℃,在夏季最小,最大值分别可达5.15℃、15.25℃;横桥向和纵桥向桥塔表面温差最大值分别达到9.15℃、11.88℃,远大于《公路斜拉桥设计细则》(JTG/T D65-01—2007)推荐值±5℃;接近正南方向的塔壁局部温差最大,沿壁厚方向的温差分布接近指数形式,冬季和夏季温度衰减系数最大值分别为4.50、5.01,故冬季桥塔壁板局部温度分布较夏季更不均匀;桥塔温度效应同样在冬季最大,1天中最大桥塔偏位超过40mm,白天桥塔偏位变化值超过15mm,不利于施工过程中的桥塔偏位监测;桥塔根部竖向最大拉应力达到2.2MPa,桥塔根部同样产生较大水平向拉应力,纵桥向和横桥向最大拉应力分别为1.82、0.82 MPa,均发生在桥塔内侧,在与其他作用组合时可能会造成桥塔开裂,建议在桥塔塔壁内侧布置一定量的钢筋网片来控制裂缝;在进行高原高寒地区桥塔设计和施工控制时,应充分考虑温度效应带来的不利影响。
The calculation method of temperature field boundary conditions for concrete structures is analyzed. Based on the H-shaped concrete bridge tower of Qinghai Haihuang Bridge as the engineering background, the distribution of temperature distribution of bridge towers under typical four-season weather in the alpine region of the plateau is calculated. Temperature difference and local temperature difference of the tower wall, the most unfavorable temperature load of the bridge tower is determined, and the overall finite element model of the bridge tower is established. The temperature effects such as deviation, vertical stress, lateral stress and longitudinal stress of the bridge tower are analyzed. The results show that the temperature difference between the tower surface and the bridge tower is the largest in winter and the maximum value reaches 11.88 ℃ and 20.79 ℃ respectively in summer and the minimum and maximum values in summer reach 5.15 ℃ and 15.25 ℃ respectively. The maximum temperature difference to the surface of the bridge tower reaches 9.15 ℃ and 11.88 ℃ respectively, which is much larger than the recommended value of ± 5 ℃ for the Design Rules of Highway Cable-stayed Bridges (JTG / T D65-01-2007). The local temperature difference near the south wall The maximum temperature distribution along the wall thickness direction close to the exponential form, the maximum temperature attenuation coefficient in winter and summer were 4.50,5.01, so the local temperature distribution of winter bridge tower wall is more uneven than in summer; bridge temperature effect is also the largest in winter , The deflection of the largest bridge in one day exceeds 40mm and the deviation of the bridge during the day exceeds 15mm, which is not conducive to monitoring the deflection of the bridge during construction. The maximum vertical tensile stress at the root of the bridge reaches 2.2MPa. Resulting in a greater horizontal tensile stress, longitudinal and transverse bridge maximum tensile stress of 1.82,0.82 MPa, respectively, occurred in the inner side of the pylons, in combination with other roles may cause the tower pylon cracking, it is recommended in the tower tower Inside the wall layout of a certain amount of steel Chip to control the crack; when the pylons carrying high altitude alpine region design and construction control, should take full account of the adverse effects caused by temperature effects.