Research On Mechanical Behavior Of Damaged Concrete Beams Strengthened With BFRP Sheet

Due to the economic fast growing, highway traffic loads are increased and become more serious. Therefore, the bridges structures have been damaged frequently and the bearing capacity decreased with time. In China, the process of bridges construction is focused on the combination of new construction and strengthening methods to build new bridges or to strengthen old bridges. Comparing with new construction of bridges structure, the strengthening methods can save about40%of the investment costs and they can reduce the costs about50%. Thus it has evident economic benefits. The reduction of bearing capacity of bridge structure includes two main aspects of flexural and shear capacity. Moreover, most damages are denoted by deflection, cracks and failure mode etc. Basalt fiber reinforced plastics has a high tensile strength and modulus of elasticity. At the same time, it has higher physical performance, such as good adhesion, heat resistance, and corrosion resistance. Thus, basalt fiber reinforced plastics is ideal for civil engineering structures or construction components, and it is a perfect choice especially for seismic strengthening of concrete structures.According to the experimental works in the laboratory of Reinforced Concrete (RC) beam strengthened with Basalt Fiber Reinforced Plastics (BFRP), the calculation method of flexural capacity, shear capacity, deflection and crack were studied to provide theoretical essence for damaged of RC beam strengthened with BFRP sheet. In this thesis the flexural behavior of RC beam strengthened with BFRP sheet was studied. The important factors of the experiments programs include varying of beam reinforcement ratio, number of BFRP sheet layer; pre-load and loading step history were considered. Yield load, failure load and strain of steel, concrete’s strain, basalt fiber’s strain were predicted and analyzed. Then the shear capacity of RC beam strengthened with BFRP sheet was analyzed for different shear span ratio, number of BFRP sheet layer and pre-loading program within experimental works.At the same time, the deflection and cracks values of damaged RC beam strengthened with BFRP sheet with the increasing of the load were analyzed in this thesis. The changing rule of infection and cracks of damaged RC beam strengthened with BFRP sheet was analyzed. The calculation method of deflection and cracks were measured to beam’s stiffness improvement and cracks width reduction.This study was presented HAYI bridge that was strengthened with BFRP sheet to verify the validity of the presented calculation methods of flexural and shear capacity of damaged RC beam strengthened with BFRP sheet. These calculation formulas can be used to in the actual strengthening construction cases.