自应力混凝土在旧桥加固中的抗裂性研究

A study on the crack resistance of self-stressing concrete for old bridge rehabilitations

钢纤维自应力混凝土作为一种新型的纤维增强复合材料应用于旧桥加固目前还比较少见。基于8根钢纤维自应力混凝土-钢筋混凝土两跨连续叠合T形梁抗弯试验,研究了钢纤维自应力混凝土作为加固材料在简支转连续体系法加固旧桥中的抗裂性能。模型试验结果表明,钢纤维自应力混凝土产生的自应力可明显降低连续梁负弯矩区使用阶段的弯矩值,用钢纤维自应力混凝土加固的连续叠合T形梁负弯矩区混凝土的开裂弯矩较用普通混凝土加固提高51.4%～121.0%。同时根据已有的单向自应力理论模型,推导了钢纤维自应力混凝土-钢筋混凝土叠合T梁后加叠合层自应力值的计算方法。建立了简支转连续体系后连续梁负弯矩区混凝土正截面的抗裂计算公式,为旧桥加固设计提供参考。

Steel Fiber Reinforced Self-Stressing Concrete （SFRSSC） as a new type of fiber reinforced composite material is not yet widely accepted for rehabilitation of old bridges. Based on the flexural experiments of 8 composite SFRSSC-RC continuous T-beams, the crack resistance of steel fiber reinforced self-stressing concrete for the rehabilitation of old supported-continuous bridges is investigated. The model test results indicated that the SFRSSC composite layers may effectively decrease the moment in the negative bending moment area in the service phase and enhance the cracking moments by 51.4%-121.0% more than conventional concrete layers. According to the existing theoretical model on one-way self-stress, a procedure for determining the self-stress of the SFRSSC layers is presented. A formula for evaluating the crack resistance of composite SFRSSC-RC continuous T-beams in the negative moment area is derived as a reference for old bridge rehabilitation design.