预应力抽柱改造技术研究与实践

Research and practice of prestressed cutting column transformation technology

针对两种不同的抽柱类型,提出了对应的预应力加固改造方法。首先对抽柱前后结构内力的变化做了分析,并提出了预应力加固改造方案,然后利用数值模拟的方法对预应力抽柱加固改造全过程进行了受力分析,最后结合工程实践成果得出结论:通过预应力态、荷载态的合理设计,预应力抽柱改造技术可以克服其他改造方法无法避免的原构件应力超前和新增构件(或补强材料)应变滞后的缺点;预应力的引入,在原抽柱位置对被加固梁起到了弹性支座的效果,可有效改善抽柱后结构的正常使用极限状态性能;数值模拟分析结果表明,预应力态、荷载态所对应的预应力筋的有效应力相差不大,因此,预应力抽柱改造设计时,预应力张拉控制应力仍可按《混凝土结构设计规范》(GB 50010—2010)选取,无需再考虑折减。

For the two different types of cutting columns,the corresponding prestressed reinforcement method was proposed.First the variation of internal force of the structure before and after the column being cut was analyzed and the prestressed reinforcement modification scheme was proposed;then the numerical simulation method was used to analyze the whole process of the prestressed cutting column reinforcement and reconstruction;finally combined with the engineering practice results,it is concluded that:through the reasonable design of prestressed state and load state,the prestressed column reforming technology can overcome the disadvantages of the stress rise of the original component and the strain lag of the newly added component(or reinforcing material)that cannot be avoided by other reforming methods;the introduction of prestressing force has the effect of elastic bearing on the strengthened beam at the position of the original pumping column,which can effectively improve the normal service limit state performance of the post-column structure;numerical simulation analysis results show that the effective stress of the prestressed tendons corresponding to the prestressed state and the load state is not much different.Therefore,control stress for tensioning can still be selected according to the Code for design of concrete structures(GB 50010—2010),no need to consider discounted.