Experimental Study On The Flexural Behavior Of Reinforced Cantilever Beams Strengthened With Near-surface-mounted FRP Tendons

Reinforced concrete structure, damaged from their own and other reasons as time, need repairing and reinforcing, and Structural Strengthening has become a hot spot of civil engineering researches at present. FRP (Fiber Reinforced Polymer) is widely used in the structural strengthening field of reinforced concrete because of its light weight, high strength, corrosion and other advantages. In recent years, Near Surface Mounted FRP Method is proposed by foreign scholars, which has many advantages compared with Externally Bonded FRP Method. Therefore many scholars do studies on the Near Surface Mounted FRP Method. Currently many researches mainly focus on the flexural behavior of the simply supported beam with the Near Surface Mounted FRP Method. Combined with contemporary needs of present projects, this paper reinforces four cantilever beams with Near Surface Mounted FRP tendons, then analyzes their damage, capacity and deformation through different parameters, the main research results are as follows:(1) Four cantilever beams strengthened with FRP tendons are tested, the results show that the ultimate bearing capacity of the strengthened beams improves 48%―64% compared to the non-strengthened beams, Therefore, the Near Surface Mounted FRP tendons reinforced method is an effective method to reinforce cantilever beams.(2) In this paper, 3 cantilever beams are shear-strengthened with the BFRP and CFRP tendons and are compared with the non-shear-strengthened cantilever beams. The results show that, the Near Surface Mounted BFRP tendons shear-strengthened can weaken the flexural capacity of the strengthened beams, but it can control the inclined cracks, and the impact is more obvious with the increasing shear reinforcement.(3) In this paper, the secondary load of cantilever beam though appling sustained loading are tested and are compared with direct reinforcing beams, its flexural capacity is lower, while the deflection is higher.(4) Based on the experiment, the formulas of flexural capacity and flexural rigidity of cantilever beam are proposed. Then the applicability and accuracy of the proposed for mulas are validated by comparing with the experimental results.