PSI - Issue 28

Kais Douier et al. / Procedia Structural Integrity 28 (2020) 986–993 Douier et al./ Structural Integrity Procedia 00 (2020) 000–000

988

3

Another study was conducted by Rasheed et al. (2017), to investigate the effect of anchorage on flexural strengthened RC beams’ strength and ductility. The behavior of 10 RC beams were investigated, nine of which were externally strengthened in flexure using Aluminum Alloy (AA) plates, and one of the RC beams was kept as a control specimen. A total of four strengthened RC beams had no end U-Wrap CFRP end anchors, while four strengthened RC beams had one and two layers of U-Wrap CFRP end-anchors. Also, one strengthened RC beam had end as well as intermediate U-Wrap CFRP anchors. The study concluded that the specimens encountered an increase in strength that ranged from 13-40 %, when compared to the control unstrengthened beam. Also, end anchors help localize debonding while beams with no end anchorage experienced a full debonding failure. Thus, the specimen’s ductility was also extremely enhanced by using end anchors. However, the usage of end anchors had no significant effect on the strength of RC beams. 2. Research significance and objectives Externally strengthening RC beams have been used as an adequate procedure to increases the beam’s ultimate load carrying capacity. However, this procedure reduces the strengthened beam’s ductility significantly. Thus, to reduce the negative ductility effect of externally strengthening RC beams, researchers mostly investigated the use of end anchorage systems on strengthened RC beams. However, the literature is still lacking the adequate knowledge on the effects of end and intermediate U-Wrap CFRP anchorage systems installed on externally strengthened RC beams with mortar bonded GSM sheets. The main aim of this study is to investigate the effects of end and intermediate U-Wrap CFRP anchorage systems on mortar bonded GSM sheets attached to RC beams in flexure. This study examines the ductility, strength, and failure modes of externally strengthened RC beams before and after the use of end and intermediate anchorage systems. 3. Experimental program 3.1. Test specimens A total of fur RC beams were investigated. All beams had the same dimensions and cross section. The beams had a total length of 2000 mm, a width of 140 mm, and depth of 280 mm. the RC beams were also reinforced with two 8 mm diameter top steel rebars, two 12 mm diameter bottom steel rebars, 8 mm diameter steel stirrups with 120 mm spacing between them along the entire length of the RC beam. Figure 1 shows the dimension and reinforcement detailing of the cast and RC beams used in this study.

2Φ8mm

Φ 8 mm@120 mm C‐C

2Φ8

Φ 8 mm@120 mm C‐C

42 mm

236 mm

2Φ12 mm

280 mm

140 mm

150

150

6 sp. @120 mm = 720 mm

2Φ12

140 mm

2000 mm

(a)

(b)

Fig.1. RC beams reinforcement details and dimensions in longitudinal view (a), and cross-sectional view (b)

3.2. Test matrix This study investigated a total of four RC beams. The first specimens were unstrengthened to serve as a benchmark specimen, the second beam was only strengthened with mortar bonded GSM sheets in flexure (SMM) and was also