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为了研究锈蚀钢筋混凝土梁采用钢板加固后以及加固后二次锈蚀时的力学性能,通过设计9片试验梁(混凝土强度等级为C25,受拉钢筋的直径为22mm),并将试件按照保护层厚度(25,30,35mm)分成3组,每组包括1片锈蚀梁、1片锈蚀加固梁和1片锈蚀加固再锈蚀梁,其中锈蚀梁和锈蚀加固梁的设计锈蚀率为10%,锈蚀加固再锈蚀梁的设计锈蚀率为15%。通过对试件梁进行单点加载的方式,分析了试件梁的跨中截面应变、挠度、裂缝开展规律、破坏模式和承载力状况。试验研究表明:锈蚀梁和锈蚀加固梁的跨中截面应变基本符合平截面假定,而锈蚀加固再锈蚀梁总体上不再符合此假定,同时钢板提高构件承载力的本质是增加截面的受压区高度;锈蚀梁在钢筋屈服后挠度出现突变,而锈蚀加固梁和锈蚀加固再锈蚀梁由于钢板能够承担部分荷载,挠度随荷载变化较为平缓;锈蚀梁在锈蚀率较小时表现为适筋梁破坏,而锈蚀加固梁和锈蚀加固再锈蚀梁均表现为斜拉破坏;受拉钢筋的锈蚀和混凝土的劣化,使得部分锈蚀加固梁二次锈蚀后的极限承载力比锈蚀梁低,钢板的加固效果完全被抵消;在保护层和钢板厚度相同时,当主筋锈蚀的不均衡性越大,梁的极限承载力越小,当主筋锈蚀较均衡时,二次锈蚀率每增加1%,极限承载力下降10~15kN。
In order to study the mechanical properties of corroded RC beams after steel reinforcement and secondary corrosion after reinforcement, nine test beams (concrete strength grade C25, tensile strength of 22 mm) were designed and tested according to the protective layer The thickness (25, 30, 35 mm) is divided into 3 groups, each group includes 1 corroded beam, 1 corroded reinforced beam and 1 corroded reinforced re-corroded beam. The design corroded rate of corroded beam and corroded reinforced beam is 10% Reinforced re-corroded beam design corrosion rate of 15%. By means of single-point loading on the specimen beam, the deformation, deflection, crack propagation law, failure mode and bearing capacity of the mid-section of the specimen beam are analyzed. The experimental results show that the cross-section strain of corroded beams and corroded beams basically conforms to the plane-section assumption, while the corroded and strengthened corroded beams generally do not conform to this assumption at the same time. The ultimate bearing capacity of the members is to increase the compressive zone The corrosion behavior of the corroded beams changed obviously after the yielding of the corroded beams. However, the corroded beams showed some abrupt changes as the corroded beams strengthened, The corroded reinforced beams and the corroded reinforced re-corroded beams show the cable-stayed failure. The corroded steel and the concrete deteriorate the ultimate bearing capacity of the partially corroded reinforced beams, which is lower than that of the corroded beams. The reinforcing effect of the steel plates is complete When the thickness of the protective layer is the same as that of the steel plate, the ultimate bearing capacity decreases with the increase of secondary corrosion rate when the corrosion of primary reinforcement is more equal to 1% when the unbalanced corrosion of the main reinforcement is larger and the ultimate bearing capacity of beam is smaller. 10 ~ 15kN.