从短期试验结果预测新建预应力混凝土梁收缩和徐变的长期效应

基于计及钢筋配筋率、预应力钢筋松弛等影响的桥梁收缩、徐变长期效应计算式,提出了从梁体混凝土短期试验值推算相应素混凝土在该桥梁工作环境下收缩应变及徐变系数的方法;结合CEB FIPMC90收缩模型与徐变模型思想,得出计算桥梁素混凝土收缩应变及徐变系数的CEB FIPMC90修正公式。理论分析与试验结果比较表明,预测理论值给出了较好的精度。该预测方法,不需做材料的收缩、徐变试验,亦避免从标准环境下试验值推算桥梁工作环境下收缩、徐变可能产生的误差。

Prediction of Long-term Effect of Creep and Shrinkage on Newly-built Prestressed Concrete Bridge Based on Short-term Test Results

According to the equations established for the calculation of the long-term eff ect of creep and shrinkage on the bridge caused by the ratio of reinforcing stee l bars and the relaxation of the bars, a method of deducing the shrinkage strain and creep coefficient from short-term test of bridge plain concrete is put for ward. A modified formula CEB-FIP (MC90) is obtained for computing shrinkage str ain and creep coefficient of bridge plain concrete following the concept of CEB -FIP (MC90) for the shrinkage model and creep model. The comparison between the theory analysis and the test results shows that the predicted value holds a goo d accuracy. When the method is used, there is no need to implement material test for shrinkage and creep, thus it can avoid the errors that might be resulted fr om deducing the real shrinkage and creep of concrete under the bridge working en vironment through the test result obtained under the standard condition.