预应力碳纤维板加固钢-混凝土组合连续梁负弯矩区试验

Strengthening of continuous steel-concrete composite beams in negative moment region using prestressed carbon fiberreinforced polymer plates

为了研究预应力碳纤维板加固钢-混凝土组合连续梁负弯矩区的受力性能,设计了3根6.2 m箱形组合截面的两跨连续梁试件,包括2根加固梁和1根对比梁。碳纤维板布置在负弯矩区混凝土板顶面,通过新型装配式预应力锚固系统进行后张有粘结加固,2根加固梁的预应力水平分别为20%和35%。结果表明:采用预应力碳纤维板加固钢-混凝土组合连续梁的负弯矩区,中支点截面的抗弯极限承载力分别提高了19.4%和28.5%,且抗裂性大幅增强;碳纤维板加固可限制裂缝的形成、发展,减小使用阶段的挠度和裂缝宽度,同时提高极限状态下的变形能力;截面应变符合平截面假定。最后,提出了连续组合梁中支点截面抗弯极限承载力的计算方法。

To investigate the flexural behavior of continuous steel-concrete composite beams strengthened with prestressed carbon fiber-reinforced polymer(CFRP)plates in negative moment region,three 6.2 m two-span continuous beams were tested to failure.The specimens included two strengthened beams and one unstrengthened control beam,which had steel box-concrete composite section.The CFRP plates were prestressed to 20%and 35%of the tensile strength respectively by an innovative fabricated anchorage system and installed over the top surface of the concrete slabs.Experimental results show that the ultimate flexural capacity of the central support sections increased 19.4%and 28.5%respectively by the use of prestressed CFRP plates.The crack resistance in the negative moment region was enhanced significantly.The strengthening contributes to the decrease of the mid-span deflection and crack width under service condition,while improving the ultimate deformation at failure stage.The strain distribution along the crosssection conforms to plane-section assumption.The calculation method of the ultimate flexural capacity for central support section is proposed.Good agreement between experimental and theoretical results is achieved.