A is also submitted in partial fulfillment of the condition for the Master of Civil Engineering degree. The general conclusions of the work were documented along with recommendations for future studies and development of structural properties of shear-strengthened AB beams. I also thank all the faculty members of the Department of Civil and Environmental Engineering at the United Arab Emirates University for their continuous support and encouragement.
In the design of a reinforced concrete (RC) member, the deflection is usually considered first, leading to the design of the section and placement of the reinforcement to provide the necessary re-supply moment. Due to material inhomogeneity, non-uniformity and non-linearity in material response, presence of cracks, presence of reinforcement, etc., the behavior of reinforced concrete in air is relatively complex (MacGregor and Wight). 2005). Steel in concrete is usually protected from corrosion by a passive film of iron oxides on the steel, which is a result of the alkaline environment of the concrete.
In both of the above applications, the FRP materials used are usually unidirectional (with all fibers oriented along the length of the sheet). Flexural Reinforcement: In this application, FRP materials are bonded to the ten-ion and/or lateral faces of a concrete beam to provide additional tensile reinforcement and to increase the member's strength in bending. These factors include the fiber and matrix type, the fiber volume content and the orientation of the fibers in the matrix.
A complete description of the test-et-up in trumentation, control and loading procedure is presented in the same chapter. Chapter (6) summarizes the general conclusions of the work together with recommendations for future research and developments regarding the performance of RC beams.
In the displacement span of the test area, the spacing of the hangers was chosen to allow for hearing loss. The second layer was bonded on the two sides of the specimen with the fiber direction parallel to the beam axis. The results also showed that the second layer, which was installed horizontally on top of the first U-wrap in the third scheme, improved the shear capacity by providing horizontal restraint.
The factors considered in this e-periment were the number of CFRP plies used for hearing reinforcement and the end. The experiment consisted of testing 1 2 full-scale T-beams isolated from the building sawn from the right of the floor. The study showed that increasing the amount of transverse steel reduced the contribution of EB. The contribution of concrete to hearing resistance was all 0 influenced by the longitudinal steel reinforcement ratio. 2005) studied the effectiveness of shear strengthening of RC members using CFRP. The parameters investigated were the CFRP ratio, the cross steel ratio and size of the specimens.
The result also showed that increasing the transverse breeding ratio reduced the contribution of CFRP to shear resistance. The result showed that EB-CFRP increased the shear capacity of the beam exponentially with that of the control beams, depending on the effective depth (d). One of the observed failure modes was due to the debonding of more than two CFRP strips.
In the U-shaped beams, the failure occurred in delamination before the ultimate deformation of the CFRP. 2009) investigated the acoustic behavior of full-span RC beams reinforced with CFRP. All the results showed that bonded and unbonded CFRP reduced the beam's acoustic defect ductility. The contribution of CFRP material was not proportional to the amount of CFRP material used.
In the second phase, three of the damaged beams were repaired using epoxy injection and. The ultimate load increased, with an increase in the bonded length of the rod. The concrete compressive strength was 3 1 M Pa and the assistance ratio was 3. The results showed that SM-FRP bars were effective in improving the shear capacity of RC beams.
The contribution of the N SM -CFRP strengthening system is limited by the concrete tensile strength. In the case of the mortar, the ultimate load alv.: ay was only about half that obtained with the resin.
The beam strengthened with the E B-CFRP system failed by the sudden detachment of the EB-CFRP sheets accompanied by the separation of both lateral concrete covers at the level of the wire piles (Figure 4.2b). The specimens strengthened with SM-GFRP y tem exhibited a slightly reduced stiffness compared to that of the unstrengthened beam. After crack initiation, the EB-CFRP layer resulted in a significant reduction in the diagonal strain plane crack growth rate relative to that of the weathered and undisturbed beam.
The growth rate of the diaaional to deformation air crack decreases with the increased number of CFRP layers. SM-GFRP reduced the rate of increase in diagonal crack strain in the post-cracking stage relative to that of the corroded unreinforced specimen. The rate of increase in diagonal complementary strain was higher for specimen C 1 - 1 relative to specimen C I - EB 1.
The rate of increase of the CFRP strain in the second stage decreased with increased number of EB-CFRP sheets. The higher the number of C F RP layers, the lower the value of this threshold. Longitudinal splitting cracks were observed at the top surface of the beam at the peak load.
The use of EB-CFRP in combination with SCP+PAF mechanical end anchorage system had no effect on either the beam ductility or the rate of stiffness degradation in the post-peak stage relative to that of the EB-CFRP. Increasing the number of EB-CFRP layers had no effect on the deflections of the beams with SCP+PAF mechanical end anchorage system. After crack initiation, the EB-CFRP y tem reduced the rate of increase of diagonal defonnation acro cracks relative to that of the control unstrengthened beam.
However, the specimen showed greater diagonal displacement across the cracks in the second shear test compared to that of the first test. The rate of CFRP strain increase in the second stage decreased with an increased number of EB-CFRP layers. I believed that local detachment happened at the end of the second phase that caused it.
The available analytical model has been published in the literature for prediction of the EB-CFRP audience strength. The international guidelines and standards were used to predict the design value of the EB-CFRP shear resistance Vjd. The relationships between predicted EB-CFRP shear resistance and the experimental values are given in Table 5.
However, all guidelines/standard equations provided conservative predictions for the design value of the EB-CFRP shear resistance when three layers of EB-CFRP were used at 1 5% stil11.lps corrosion. When two and three layers of E B-CFRP were used at 1 5% corrosion, all analytical models gave reasonable predictions for the nominal EB-CFRP shear resistance except the model of Khalifa and Nanni 2000, which tended to overestimate the nominal E B-CFRP shear resistance. It should be noted that the R* factor introduced by Pellegrino & Modena 2002 resulted in a non-reasonable prediction for the nominal EB-CFRP hearing ability.
The relationship between the predicted E B-CFRP audibility and the experimental values is given in Table 5. The analytical prediction is also shown against the e perimental value in Figure 5.9. 10 and Figure 5.9, it can be seen that all analytical models provided a conservative prediction for the nominal EB-CFRP shear for all test specimens, except for specimen U-EB2, which was strengthened with a two-layer EB-CFRP plate without mechanical end anchorage. When two and three layers of EB-CFRP were used at 15% corrosion, all guideline/standard equations overestimated the nominal shear resistance of E B-CFRP, except HB 305, which provided a conservative prediction. However, all the guidelines/standard equations provided conservative predictions for the design shear resistance value of E B-CFRP when three layers of EB-CFRP were used at 1 -0 0 stirrup corrosion.
At 80'0 tirrups corrosion, all analytical models published in the literature by independent researcher examined in this study provided conservative prediction for the nominal EB-CFRP shear resistance. When two and three layers of EB-CFRP were used at 1 5% corrosion, all analytical models provided reasonable predictions for the nominal E B-CFRP shear resistance except the model by Khalifa and Nanni 2000 which tended to overestimate the nominal EB-. CFRP shear resistance. It should be noted that the R * factor introduced by Pellegrino & Modena (2002) led unrealistically. prediction for the nominal EB-CFRP shear resistance.
In fact it gave negative value \ ben a layer of E B-FRP wa u ed. low r tiffilp corrosion of 8%, analytical approach by anni et a!. 2004) provided the factory sati prediction of the contribution of the SM-GFRP system to hear capacity. The higher the tin C01 concentration of 1 5%, the analytical approach tends to 0 times the shear strength of rSM-GFRPP. When an EB-CFRP layer was used without bottom anchorage, all guidelines/standards provided conservative prediction for CFRP shear strength, except for TG 9.3 strand which overestimated CFRP shear strength by about 50%.
All of the conservative guidance/standard pro-designed predictions for CFRP hear the response when an EB-CFRP layer is used in combination with an appropriate end anchorage. For the EB-CFRP double-layer reinforced beam in combination with the C P+PA F end anchorage system, all guidelines/standards except the TG 9.3 thread provided a conservative prediction for the nominal CFRP.
