现浇砼PC连续箱梁病害分析和体外预应力加固的立论问题

Analysis of Damage Crack of Field - making PC Continuous Box Girder and Argumentation of Outer - Presress Strengthening

我省现浇PC连续箱梁的病害比较普遍,病因众口不一。文章从裂缝所在的部位、方向和多种形态入手,进行了分析,找出了病害的真正原因——早期混凝土收缩所致。由于支架和底模对具有摩阻约束,使强度很低的混凝土受拉开裂。防治的有效办法是缩短现浇段的长度。文章还探讨了体外预应力加固方案的立论问题,为定量的选定体外预应力加固提供依据。

It is a common phenomenon that damage cracking appeared in field - making PC continuous box girder, but the causes of it remains controvertibale. Through analyzing of the location, direction, and forms of cracking , it found that real cause is the shrinkage of the concrete, because of bracket and bottom mould have the friction resistance , the low strength concrete tents to be drawn creack. the effective measure is to shorten the length of the field - making girder. The paper also discussed the argumentation of outer - prestrss strengthening and provide specification for option of outer - prestress strengthening.