混凝土斜拉桥施工控制中温度对主梁标高的影响
Effect of temperature on main beam elevation in construction control of concrete cable-stayed bridge

为研究温度对主梁标高的影响，采用基于实测温度场的数值分析方法，研究索、塔、梁温度轴向应变和曲率等相关参数对主梁标高的敏感性，并分析主要天气条件（持续晴天、阴雨天、昼夜温差大、季节变换）下，温度对主梁标高的影响。结果表明：采用基于实测温度场的数值分析方法能快速、精准地计算温度场对主梁标高的影响；由于斜拉索的牵制作用导致主梁温度曲率变化对主梁标高的影响较小；对于混凝土斜拉桥，凌晨温差很小时，主塔及主梁曲率对主梁标高影响较小，斜拉索、主塔和主梁温度轴向应变对标高影响显著；塔壁中间测点温度可视为全截面平均温度计算主塔轴向应变；仅考虑索、塔、梁轴向温度应变对主梁标高的影响与温度总影响量较为接近，可用于快速评估温度对主梁标高的影响；夏季持续晴天、阴雨天，甚至秋季昼夜温差大的持续晴天天气条件下，日出前凌晨温度场均较为均匀，能较为有效地避免温度影响，但由于索温偏低导致主梁标高略偏高，日出后由于索温升温快使标高快速下降，但在日出后日照强度不大的1~2 h内，标高降幅有限且更接近理想状态，此时的温度场也能为施工控制提供便利；夏秋转变季节，气温突降时凌晨温度场更为复杂，施工时温度场的影响难以避免。
In order to study the influences of temperature on main beam elevation, a numerical analysis method based on measured temperature field was adopted in this paper to study the sensitivity of relative parameters on main beam elevation, such as axial strain and curvature of cables, towers and girders. Moreover, temperature effect on main beam elevation was analyzed under main weather conditions (continuous sunny days, rainy days, large temperature differences between day and night and seasonal change). The results show that the numerical analysis method based on measured temperature field can quickly and accurately calculate the influence of temperature field on main beam elevation. Due to the containment effect of stay cables, the temperature curvature changes of main beam have low influence on its elevation. When the temperature difference is very small during the wee hours, the influence of curvature of main towers and beam on main beam elevation is also small for concrete cable-stayed bridges. The axial strain affected by temperature of stay cables, main towers and main beam has significant influence on main beam elevation. Temperature of measuring point in the middle wall of main towers can be roughly regarded as the average temperature of the whole section to calculate the axial strain of main tower. Considering only the influence of axial temperature strain of cable, tower and beam on main beam elevation is close to the total temperature effect, which can be used to quickly evaluate the temperature effect on main beam elevation. On continuous sunny or rainy days in summer and continuous sunny days with large temperature differences between day and night in autumn, it is effective to avoid the temperature influence because of uniform temperature filed before sunrise. Main beam elevation is slightly high due to low cable temperature at this time, and goes down quickly with cable temperature growing rapidly after sunrise. Within 1 to 2 h after sunrise, as the sunshine intensity is not strong, the decreasing amplitude of elevation is limited and closer to