Bending performance of steel beams with circular web openings strengthened with CFRP plates: a numerical study

Strengthening steel structures through the traditional method of adding extra steel plates is deemed ineffective due to emerging issues, such as an increase in the overall weight of the structure. The steel plates utilized are also prone to corrosion. Strengthening steel structures using carbon fiber-reinforced polymer (CFRP) is a smart solution, given this material has many outstanding characteristics. This paper presents the results of numerical investigation into the performance of steel beams having circular web openings strengthened using CFRP plates. The number of web openings on steel beam varies among 3, 5, 7, and 9. The length of CFRP plates is also varied, namely 500 mm, 700 mm, 900 mm, 1200 mm, and 1600 mm. It can be confirmed that CFRP has only a small effect on the improvement of elastic stiffness of the beam, i.e., less than 10%. The presence of CFRP reduces displacement ductility for beams with the number of web openings of three and five. However, CFRP can increase displacement ductility for beams with the number of web openings of seven and nine, depending on length of CFRP used. Additionally, CFRP provides a positive contribution to the improvement of bending strength of steel beams, although the value varies according to length of CFRP plate used.