混凝土箱梁水化热温度徐变应变分析

摘要

针对桥梁设计中混凝土箱梁水化热温度应变难以精确分析的现象,基于预制梁场混凝土箱梁水化热温度应变现场试验,采用初应变增量有限元法建立混凝土箱梁水化热温度应变的弹性徐变理论隐式解法数值模型,分析实测水化热应变、温度徐变应变及温度弹性应变三者之间的差异,研究混凝土箱梁水化热温度应变受徐变影响的规律.研究结果表明:拆模后箱梁顶极、底板水化热温度应变均为压应变且算术平均值基本一致;混凝土箱梁顶板水化热温度应变变化速率略小于底板水化热温度应变变化速率;徐变对混凝土箱梁水化热温度应力应变影响非常大,实际应变仅约为温度弹性应变的一半,因此,早龄期混凝土结构温度弹性应力减半更符合实际情况;混凝土箱梁水化热温度应变实测数据略大于温度徐变应变计算值,说明本文数值模型可准确有效模拟箱梁水化热温度应变真实状态、有助于桥梁分析设计.%Field test of hydration heat on prefabricated concrete box girder was carried out to study the temperature strain of hydration heat on prefabricated concrete box girder. The numerical model of elastic creep theory with implicit method about temperature strain of hydration heat was established by the increment of initial strain method. On the basis of field test and numerical model, the difference among test data of hydration heat strain, thermal creep strain and thermal elastic strain was contrasted and analyzed. The influence of creep on temperature strain of hydration heat on concrete box girder was studied. The results show that the arithmetic means of compression strain on roof and floor are basically coincident after form removal. The change rate of compression strain on roof is slightly lesser than that of floor of concrete box girder. The influence of creep on temperature strain of hydration heat is great. And test value of strain is only about half of thermal elastic strain, so the influence of creep on hydration heat stress should be considered. The test value of hydration heat strain is slightly higher than calculated value of thermal creep strain- So this numerical calculation is reliable and well tally with the actual situation.