Usage of EB-CFRP for Improved Flexural Capacity of Unbonded Post-Tensioned Concrete Members Exposed to Partially Damaged Strands

Self Cite

Studies on the flexural behavior of post-tensioned beams subjected to strand damage and strengthened with near-surface mounted (NSM) technique using carbon fiber-reinforced polymer (CFRP) are limited and fail to examine the effect of CFRP laminates on strand strain and strengthening efficiency systematically. Furthermore, a design approach for UPC structures in existing design guidelines for FRP strengthening techniques is lacking. Hence, the behavior of post-tensioned beams strengthened with NSM-CFRP laminates after partial strand damage is investigated in this study. The testing program consists of seven post-tensioned beams strengthened by NSM-CFRP laminates with three partial strand damage ratios (14.3% symmetrical damage, 14.3% asymmetric damage, and 28.6% symmetrical damage). The experimental results showed that the use of CFRP laminates significantly increases the flexural capacity by up to 17.4 to 20.4%, corresponding to a strand damage ratio of 14.3 and 28.6%, respectively, enhances the stiffness, and reduces strand strain by up to 15.8 to 22.2%. However, the flexural stiffness of strengthened beams during serviceability phases is critical as strand damage ratios increase. Additionally, semi-empirical equations were proposed to predict the actual strain of unbonded strands whilst considering the effects of CFRP laminates. The suggested equations provide accurate predictions with little variance. Doi: 10.28991/CEJ-2022-08-07-013 Full Text: PDF

Section: Computing Approach For Frp-strengthened Unbonded Mn Post-ten...mentioning

confidence: 99%

Behavior of Post-Tensioned Concrete Girders Subject to Partially Strand Damage and Strengthened by NSM-CFRP Composites

Jalil

Al‐Zuhairi²

2022

Self Cite

“…In the last three decades of the prior century, the use of carbon fibre-reinforced polymer (CFRP) composites for strengthening reinforced concrete (RC) elements has become an intriguing tool for infrastructure rehabilitation. CFRP strengthening can be used in many different ways, including building new buildings and fixing old ones [1][2][3][4]. Along with analysing the general failure criteria of CFRP-RC beams, other researchers have focused on the local behaviour at the bond interface.…”

Section: Introductionmentioning

confidence: 99%

Structural Strengthening of Insufficiently Designed Reinforced Concrete T-Beams using CFRP Composites

Alobaidi,

Al-Zuhairi

2023

This study aims to compare the response of reinforced concrete (RC) T-beams strengthened with carbon fibre-reinforced polymer (CFRP) composite with that of non-strengthened control beams when subjected to monotonic two-point loading until failure for flexural once and shear again. The experimental programme tested eight RC T-beams, which included two reference beams without strengthening and six strengthened beams. The eight beams were divided into two main groups according to strengthening (flexural and shear). Experimental analysis was performed to study the effect of the CFRP laminate width in the flexural group and the spacing of CFRP U-wrap sheets in the shear group on the ultimate load capacity, load-strain relationship, and load-deflection relationship. Results show that increasing the width of the CFRP laminate in the flexural group improves the ultimate strengths to approximately 9.5%, 35%, and 41% for beams with CFRP laminate widths of 50, 100, and 150 mm, respectively, compared with the reference non-strengthened beam. The stiffness of the beams increases in direct proportion to the width of the CFRP laminate. In the meantime, decreasing the spacing of the CFRP laminate in the shear group increases the ultimate strengths to approximately 13.2%, 17.7%, and 23.5% for beams with CFRP U-wrap sheet spacings of 166, 125, and 100 mm, respectively, compared with the reference non-strengthened beam. Therefore, the spacing of the CFRP sheet is inversely proportional to the stiffness of the beam. Doi: 10.28991/CEJ-2023-09-08-05 Full Text: PDF

“…During the last three decades of the previous century, the utilisation of carbon fibre-reinforced polymer (CFRP) composites for strengthening reinforced concrete (RC) structures has emerged as a highly promising technology to address the rehabilitation of infrastructure. CFRP strengthening can be used in various ways, including to build new buildings and fix old ones [1][2][3]. In addition to analysing the general failure criterion of CFRP-RC beams, other researchers have focused on the local behaviour at the bond interface.…”

Section: Introductionmentioning

confidence: 99%

Shear Performance of Reinforced Concrete T Beams Strengthened by Carbon Fiber-Reinforced Polymer Bars

Alhilli,

Al-Farttoosi

2023

The primary purpose of this work is to investigate the shear response of T-reinforced concrete beams strengthened for shear using the embedded through section (ETS) technique when subjected to a monotonic one-point load till failure. The experimental approach included an examination of the twelve reinforced concrete T-beams, including two reference beams without any strengthening and ten strengthened beams. The twelve beams were divided into two main groups, with and without stirrups. The main variables in every group were the spacing and angle of inclination of the carbon fibre-reinforced polymer (CFRP) bars. The beams were strengthened in shear with CFRP bars inserted in the centre line of the section with different spacings and angles of inclination. The experimental analysis was performed to study the effect of spacing and angle of inclination of the CFRP bars on the ultimate load capacity, load-strain relationships, and load-deflection relationships. Results showed that the ultimate load of the beams in group one with inclined CFRP bars (45°) increased by 29.7, 22.4, and 15.5% for beams with CFRP bar spacings of 10, 15, and 20 cm, respectively, compared with the reference beam. In group one (with stirrups), the beam with inclined CFRP bars (45°) and a spacing of 10 cm has an ultimate load higher than that with vertical CFRP bars (90°) with a similar spacing by 2.6%. By contrast, the beam with inclined CFRP bars (45°) and a spacing of 10 cm in group two (without stirrups) has an ultimate load higher than that with vertical CFRP bars (90°) with a similar spacing by 2.5%. Doi: 10.28991/CEJ-2023-09-10-04 Full Text: PDF