某超长预应力框架结构张拉方案分析

Analysis on Tensioning Schemes for a Super-Long Prestressed Frame Structure

针对超长预应力框架结构的张拉方案开展数值模拟分析,对结构在后浇带同步浇筑并同步张拉、后浇带分批浇筑并分段张拉两种条件下的内力分布和变形规律进行了对比;针对后浇带分批浇筑并分段张拉的情形,提出了4种张拉方案。分析结果表明:分批浇筑并分段张拉方案相较于同步浇筑张拉方案改善了边柱内力的分布,边柱最大弯矩显著降低,柱端混凝土拉应力分布情况也得到了改善;多次分批封闭后浇带并张拉后浇带所在跨的预应力筋对于结构整体性能是有利的,且随着批次的增加,这种有利效果越明显。在实际工程中,对预留的后浇带宜采取分批张拉的方案。

Numerical simulation analysis was conducted for a tensioning schemes of super-long prestressed frame structure,simultaneously,the internal force distribution and deformation law of the structure in integral pouring with synchronous tensioning and segmental pouring with segmental tensioning were analyzed and compared;four tensioning schemes were proposed and calculated respectively.The analysis results showed that compared with the overall tensioning scheme,the scheme of batched pouring and segmental tensioning could improve the internal force distribution of side columns,the maximum bending moment of side columns was significantly reduced,and the tensile stress distribution of concrete at the column ends was also improved.Additionally,it was beneficial to the overall performance of the structure by closing the post-cast strips and tensioning the prestressed reinforcement of the span where the post-cast strips were located for many times,and the beneficial effect was more obvious with the increase of batches.In the actual projects,the scheme of batched tensioning for the reserved post cast-strips should be adopted if conditions permitted.