Efficiency of flexural strengthening RC beams using fiber reinforced polymer materials

Abstract

The purpose of this study is to evaluate the efficiency of the flexural strengthening of reinforced concrete (RC) beams using the fiber reinforced polymer (FRP). The calculation procedures according to design standards including ACI 440.2R-17 and FIB-2019 are employed to assess the flexural capacity of strengthened RC beams. Three types of FRP materials, which are glass FRP (GFRP), aramid FRP (AFRP), and carbon FRP (CFRP), are used. For CFRP, three kinds of tensile strengths consisting of low (CFRP-L), medium (CFRP-M), and high (CFRP-H) levels are also utilized in calculations and assessments. A numerical model of FRP strengthening beam is developed in ANSYS and then verified with the results of design standards. Comparative studies on the efficiency of flexural capacity and cost benefit between the use of FRP sheets and a conventional retrofitting method are conducted considering a specific area of FRP sheets and 50% flexural strengthening target. The results reveal that flexural strength after strengthening based on ACI and FIB is very similar. The optimal options considering the strength and cost effects are CFRP-L and CFRP-M when using a constant area of FRP. Additionally, we suggest using CFRP-H or CFRP-M for strengthening the RC beams with satisfying a target strength improvement of 50%. Comparing with the conventional method such as section increment, using FRP is more beneficial for both required strength and costs as well.