Experimental Investigations on U- and L-Shaped End Anchored CFRP Laminate Strengthened Reinforced Concrete Beams

• Published in: Arabian Journal for Science and Engineering Vol. 37; no. 4; pp. 905 - 919
• Main Authors: Alam, Md. A., Jumaat, M. Z.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2012
• Subjects: Beams (structural); Carbon fiber reinforced plastics; Cracks; Engineering; Humanities and Social Sciences; Laminates; multidisciplinary; Peeling; Research Article – Civil Engineering; Science; Shear; Strengthening; Beam; Debonding; U- and L-shaped steel end anchors; CFRP; Reinforced concrete
• ISSN: 1319-8025; 2191-4281
• DOI: 10.1007/s13369-012-0213-6

Strengthening of reinforced concrete beams using externally bonded CFRP laminate is the most popular choice. However, premature end peeling of CFRP laminate has been shown to be the main weakness of this method. Development of high shear and normal stresses at the end of strengthening laminate is the key reason to cause end peeling which is not preventable by conventional anchoring system. This paper presents the experimental investigations on the effects of U- and L-shaped steel end anchors on CFRP laminate flexurally strengthened r.c. beams to preclude end peeling. Analytical and numerical models are also used to compare the results. In the experimental programme, four rectangular r.c. beams were fabricated and tested. One beam was left as control and the other three beams were strengthened using CFRP laminates. From the strengthened beams, one was left un-anchored while rest two beams were end-anchored using U- and L-shaped steel plates. Results showed that all strengthened beams exhibited higher crack and ultimate loads along with less deflections and crack widths as compared to those of the control beam. The un-anchored strengthened beam failed by premature end peeling with brittle manner, whereas, U- and L-shaped end anchored strengthened beams failed by shear rather than end peeling. The end anchored beams had higher failure loads compared to un-anchored strengthened beam. The analytical and numerical results are similar to the experimental findings.