Experimental Study On Durability Of Concrete Specimens Strengthened By Bfrp Sheets

As a kind of strengthening material, FRP has been widely used in strengthening concrete structures due to its advantages such as light weight, high strength, being nonmagnetic, fatigue durability and corrosion resistance. With the wide use of FRP sheets, structures strengthened by FRP sheets will be affected by various environment conditions. So it is significant to study the durability of the entire structures strengthened by FRP sheets. Many experiments on the entire performance and durability of beams reinforced by FRP sheets were conducted in previous research in many countries. But those works mainly focused on the FRP such as CFRP and GFRP and there was little experimental study on the structures strengthened by BFRP sheets which have excellent cost performance. Basing the test results, the entire environmental durability of bending concrete specimens strengthened by BFRP sheets is analyzed in this paper. This research is sponsored by 2005 National Program for Tackling Key Problem which is an international cooperation project and its numbering is 2005DFBA0002. The main work of this paper is as follows:1.With the change of parameter of freezing-thawing tests, the influence of freezing-thawing action on the mechanical properties of the concrete specimens strengthened by BFRP sheets such as the deformation of specimens and bearing capacity. The test results show that bending concrete member strengthened by BFRP sheets could meet the strengthening requirements under the condition of freezing--thawing action.Basing the established models of capacity for members strengthened by FRP andthe test results in this paper, the capacity of specimens strengthened by BFRP sheets is calculated in this paper and provide reference for capacity of peeling failure of members strengthened by BFRP sheets.2. Basing the test results, the strengthening effects of BFRP sheets and the influence of carbonization to the entire mechanical properties of concrete specimens is analyzed and studied. The study is as follows:(1)Basing the established calculation models and combined with the Code for design concrete structure, the end-peeling capacity is calculated. The calculated results are in reasonable agreement with the test results and could provide reference for the calculation of BFRP strengthening.(2)Basing on the design code for strengthening concrete structure, it is calculated the flexural capacity and the shear capacity of RC members strengthened by BFRP sheets or CFRP sheets. The calculated results show that RC members strengthened by BFRP sheets could meet the strengthening requirements. It is analyzed the cost performance of BFRP sheets and CFRP sheets. The analysis indicates that BFRP sheets have greater price advantage than CFRP sheets. The analysis indicates BFRP sheets are suitable to specific conditions of China and their use is worthy to be promoted widely.