体外预应力加固大跨度混凝土梁的试验研究

Experimental studies of external prestressing reinforced long-span concrete beam

以天津某加固改造工程为背景,通过对12根简支梁及6榀框架梁进行体外预应力加固试验,分析加固后梁体的承载能力及使用性能,提出了适合本工程的正截面抗弯承载力计算公式及力筋极限应力增量计算公式。结果表明混凝土梁采用体外预应力加固时,可以显著减小梁体跨中挠度及裂缝宽度;承载力极限状态下,可以显著提高梁体抗弯极限承载力;采用适量预应力筋,加固后梁体的破坏形态仍为适筋梁延性破坏。

With one strengthening and rebuilding project in Tianjin city as background, external pres- tressing test was conducted on 12 beams and frame beams with 6 Pin, the stiffness and crack resist- ance of beam body after strengthening were analyzed. At the same time normal section flexural bearing capacity calculation formula and ultimate stress of tendon incremental calculation formula suitable in this project were confirmed. The results showed that reinforced concrete beams with external prestress- ing could reduce significantly beam deflection and crack width, and improve significantly ultimate bearing capacity of beam bending with limit state capacity. And fitness beam ductile failure was still the failure mode of beam after strengthening design with proper prestressing tendon.