英文原文加中文翻译

英文原文加中文翻译内容摘要：

N. This load was a decrease of shear capacity by kN pared to the specimen SW31 due to the absent of the steel stirrups. In addition, the crack pattern in specimen SW31 was different from of specimen SO31. In specimen SW31, the presence of stirrups provided a better distribution of diagonal cracks throughout the shear span. In specimen SO32, strengthened with 50mm CFRP strips spaced at 125 mm, the first diagonal shear crack was observed at an applied load of 100 kN. The crack 7 propagated as the load increased in a similar manner to that of specimen SO31. Sudden failure occurred due to debonding of the CFRP strips over the diagonal shear crack, with spalled concrete attached to the CFRP strips. The total ultimate load was 262 kN with a 70% increase in shear capacity over the control specimen SO31. The maximum local CFRP vertical strain measured at failure in specimen SO32 was mm/mm (. 28% of the ultimate strain), which indicated that the CFRP did not reach its ultimate. Specimen SO33, strengthened with 75mm CFRP strips failed as a result of CFRP debonding at a total applied load of 266 kN. No significant increase in shear capacity was noted pared to specimen SO32. The maximumrecorded vertical CFRP strain at failure was mmymm (. 31% of the ultimate strain). Specimen SO34, which was strengthened with a continuous CFRP Uwrap (908), failed as a result of CFRP debonding at an applied load of 289 kN. Results show that specimen SO34 exhibited increase in shear capacity of 87, 10 and % over specimens SO31, SO32 and SO33, respectively. Applied load vs. vertical CFRP strain for specimen SO34 is illustrated in Fig. 10 in which strain gauges sg1, sg2 and sg3 were located at midheight with distances of 175, 300 and 425 mm from the support, respectively. Fig. 10 shows that the CFRP strain was zero prior to diagonal crack formation, then increased slowly until the specimen reached a load in the neighborhood of the ultimate strength of the control specimen. At this point, the CFRP strain increased significantly until failure. The maximum local CFRP vertical strain measured at failure was approxi mately mm/mm. When paring the results of beams SO34 and SO32, the CFRP amount used to strengthen specimen SO34 was 250% of that used for specimen SO32. Only a 10% increase in shear capacity was achieved for the additional amount of CFRP used. This means that if an end anchor to control FRP debonding is not used, there is an optimum FRP quantity, beyond which the strengthening effect is questionable. A previous study [11] showed that by using an end anchor system, the failure mode of FRP debonding could be avoided. Reported findings are consistent with those of other research [7], 8 which was based on a review of the experimental results available in the literature, and indicated that the contribution of FRP to the shear capacity increases almost linearly, with FRP axial rigidity expressed by ffE ( f is the FRP area fraction and fE is the FRP elastic modulus) up to approximately GPa. Beyond this value, the effectiveness of FRP ceases to be positive. In specimen SO35, the use of a horizontal ply over the continuous Uwrap (. 90176。 /0176。 ) resulted in a concrete splitting failure rather than a CFRP debonding failure. The failure occurred at total applied load of 339 kN with a 120% increase in the shear capacity pared to the control specimen SO31. The strengthening with two perpendicular plies (. 90176。 /0176。 ) resulted in a 17% increase in shear capacity pared to the specimen with only one CFRP ply in 90176。 orientation (. specimen SO34). The maximum local CFRP vertical strain measured at failure was mm/mm. By paring the test results of specimens SW32 and SO35, having the same a/d ratio and strengthening schemes but with different steel shear reinforcement, the shear strength (. 177 and kN for specimens SW32 and SO35, respectively), and the ductility are almost identical. One may conclude that the contribution of CFRP benefits the beam capacity to a greater degree for beams without steel shear reinforcement than for beams with adequate shear reinforcement. . Series SO4 Series SO4 exhibited the largest increase in shear capacity pared to the other series investigated with this research study. The experimental results in terms of applied load vs midspan deflection for this series is illustrated in Fig. 11. The control specimen SO41 failed as a result of shear pression at a total applied load of 130 kN. Specimen SO42, strengthened with CFRP strips, the failure was controlled by CFRP debonding at a total load of 255 kN with 96% increase in shear capacity over the control specimen SO41. The maximum local CFRP vertical strain measured at failure was mmymm. When paring the test results of specimen SO42 to that of specimen SO32, the 9 enhanced shear capacity of specimen SO42 (a/d=4) due to addition of CFRP strips was kN, while specimen SO32 (a/d=3) resulted in added shear capacity of 54 kN. As expected, the contribution of CFRP reinforcement to resist the shear appeared to decrease with decreasing a/d ratio. Specimen SO43, strengthened with continuous U wrap, failed as a result of concrete splitting at an applied load of 310 kN with a 138% increase in shear capacity pared to that of specimen SO41. The maximum local CFRP vertical strain measured at failure was mm/mm. 4. Design approach The design approach for puting the shear capacity of RC beams strengthened with externally bonded CFRP reinforcement, expressed in ACI design code [12] format, was proposed and published in 1998 [13]. The design model described two possible failure mechanisms of CFRP reinforcement namely: CFRP fracture。 and CFRP debonding. Furthermore, two limits on the contribution of CFRP shear were proposed. The first limit was set to co。