大跨径混凝土箱梁桥有效温度与应变的实测分析

Analysis of measured effective temperature and strains of long-span concrete box girder bridge

基于苏通大桥辅助航道桥运营期两年内实测的温度、气象和应变数据,对混凝土箱梁的有效温度与应变进行了分析。结果表明:箱梁的尺寸越小,有效温度变化的范围越大,设计基准期为100年的墩顶梁和跨中箱梁的有效温度范围分别为(-4.3℃,37.3℃)和(-6.1℃,42.2℃);大气前3天的最高(低)平均温度与箱梁有效温度的相关性系数高达0.97,通过回归分析得到的箱梁有效温度与大气前3天平均最高(低)温度的关系式,可用来对箱梁有效温度进行预测。最后提出了修正混凝土收缩、徐变效应的方法,并使用箱梁有效温度对主墩墩底混凝土的竖向相对应变和支座截面箱梁顶板混凝土的纵向相对应变进行了预测。

Based on the measured temperature, meteorological and strain data of the auxiliary shipping channel bridge of Sutong bridge during two years of operation, the effective temperature and strains of concrete box girder were studied. The results show that the smaller size of the concrete box girder, the larger range of the effective temperature. For the bridge with design reference period of 100 years, the ranges of effective temperatures of the concrete box girders at the pier top and at the middle span are （-4.3 ℃, 37.3 ℃） and （- 6.1 ℃, 42.2 ℃） respectively. The correlation coefficient between effective temperature and average high （or low） air temperature for 3 consecutive days reaches 0.97, and the equation obtained by regression analysis is quite useful in estimating the extreme effective temperature of the concrete box girder. At last, a method to modify the effect of concrete shrinkage and creep was proposed, and the relative strains at the bottom section of the main pier and at the bottom slab of the box girder adjacent to the main pier were predicted using the effective temperature of the concrete box girder.