碳纤维技术在桥梁加固工程中应用的探讨

通过对比跨度32 m铁路预应力混凝土梁用不同方法加固前后的力学性能,研究碳纤维加固技术应用的适宜场合。研究结果表明:在抗弯加固方面,碳纤维加固更适合于原结构高度较小、配筋较少、荷载变化不大的构件;对于梁高大、配筋多、活载作用大的桥梁,特别是预应力混凝土梁,因新增碳纤维的面积远远小于实体梁面积,加固后构件的刚度,钢筋应力的改善有限,其加固的效果不如预应力加固。采用黏贴碳纤维布的加固方法基本无法提高实体梁的抗裂性能,但在梁体开裂后,碳纤维对梁体的裂缝发展有较好的约束作用。

Analysis on the Applicability of CFRP in Bridge Strengthening Engineering

The application conditions of CFRP strengthening techniques are studied in this paper by comparing the mechanical behaviors of 32 m span prestressed concrete beam used in railway before and after reinforcement in different ways.The results of investigation indicate that CFRP strengthening in flexure is more practicable for these members with lower original height,lower reinforcement ratio or subjected to load with little change;but its effects on increasing stiffness of member and decreasing stress in reinforcements after strengthening are limited for these bridges with higher height,higher reinforcement ratio or subjected to heavier live load,especially for the prestressed concrete beams.And its strengthening effects are not as good as that of prestressed strengthening,in respect that the cross-section area of carbon fiber sheets are much fewer than that of the beam.The cracking resistance of beam is almost not improved by strengthening with CFRP sheets,whereas the cracks in the beam are well controlled by CFRP sheets after cracking.