桥梁短期实测数据修正高强混凝土收缩徐变模型与长期挠度预测

Prediction of Long-term Deflection and Correction of Shrinkage and Creep Model of High-strength Concrete of Bridge Based on Measured Short-term Data

为了解大跨径预应力连续箱梁桥高强混凝土的收缩徐变规律,预测其长期变形,在箱梁跨中埋置测量传感器,直接测量混凝土的收缩应变,通过增量运算理论分离出混凝土的徐变应变,对于具体桥梁的C55高强混凝土实测数据显示,现行规范的收缩徐变模型总体上会低估高强混凝土的收缩作用,而高估徐变作用。用短期实测数据修正后的混凝土收缩徐变模型预测桥梁恒载下的长期变形,由两种类型修正式的挠度估算值与实测值的比较可知,其预测精度受混凝土短期实测应变数据的完整性﹑测量精度及修正式与实测数据吻合程度的影响。

To investigate the shrinkage and creep regularity of high-strength concrete for long-span prestressed concrete of the bridge shows that if the creep and shrinkage model in the existing specification is used, the shrinkage effect is underestimated and creep effect is overrated as a whole. The long-term deflection of the bridge under dead load is predicted by the modified prediction models of creep and shrinkage based on short- term measured data. The deflection prediction values obtained by 2 modified prediction models are compared with the measured deflection. The result indicates that the prediction accuracy of the modified formula is influenced by the integrality and measurement accuracy of short-term measured strain data of the concrete,and the agreement degree between the values obtained by modified formula and measured data.