SHEAR BEHAVIOR OF SHALLOW WIDE BEAMS STRENGTHENED WITH EXTERNALLY BONDED CFRP STRIPS
Ahmed Aboul-Ela Mostafa Mohamed;
Abstract
The use of shallow wide beams in structural systems is a good solution for many architectural constraint. In addition, shallow wide beams give construction time saving because of the simplicity of formwork and reinforced placement. On the other side, shear strengthening of reinforced concrete members using externally bonded fiber reinforced polymers FRP has been increased in the last years as a fast and easy solution for increasing the load capacity of structural systems.
ECP 203-2007 has considered that beams to be shallow and wide if their depth is less than the largest of three values: 250 mm, 2.5 times the thickness of the flange, or half the width of the web.In this case, the nominal shear stress in shallow wide beams is less than the concrete shear strength, and ECP 203-2007 considers that the shear strength provided by concrete for shallow wide beams to be equal to 67% of the concrete shear strength for ordinary beams. Consequently, shallow wide beams will be designed considering that the shear resistance shall be provided only by concrete with no contribution of the vertical stirrups, so large cross sections of concrete will be provided for shallow wide beams. Neglecting the shear reinforcement contribution and reducing the concrete shear strength for shallow wide beams is very conservative in the design process, and does not exist in international codes such as ACI 318- 14 and CSA A23.3-04 that provide the same provisions to design both shallow wide beams and slender beams.
Fiber Reinforced Polymers (FRP) composites are considered an alternative material for strengthening reinforced concrete structures over traditionalmethods,such as using steel plates , steel and/or concrete jacket. FRP are lightweight, non-corrosive, easy to handling and high in tensile strength in spite of the high cost compared with the traditional methods.
This research aims to study simultaneously, the effect of vertical stirrups on the shear behavior of shallow wide beams, as well as the shear behavior of shallow wide beams strengthened in shear with externally bonded CFRP strips.
Based on the results of the experimental work, the contribution of shear reinforcement (vertical stirrups) of shallow wide beams with stirrups is significant and must be taken into consideration when calculating the shear strength of beams, The increase of stirrups volumetric ratio increases the shear capacity of shallow wide beams; Strengtheningusing narrower strips with smaller spacing is better than strengthening using wider strips with bigger spacing for the same CFRP strips volumetric ratio; Removing the CFRP strip with small anchorage length reduces the shear capacity of concrete beams; Increasing the stirrups volumetric ratio in the concrete beams reduces the shear strength due to CFRP strips strengthening; Finally increasing CFRP strips volumetric ratio increases the shear capacity of concrete beams.
ECP 203-2007 has considered that beams to be shallow and wide if their depth is less than the largest of three values: 250 mm, 2.5 times the thickness of the flange, or half the width of the web.In this case, the nominal shear stress in shallow wide beams is less than the concrete shear strength, and ECP 203-2007 considers that the shear strength provided by concrete for shallow wide beams to be equal to 67% of the concrete shear strength for ordinary beams. Consequently, shallow wide beams will be designed considering that the shear resistance shall be provided only by concrete with no contribution of the vertical stirrups, so large cross sections of concrete will be provided for shallow wide beams. Neglecting the shear reinforcement contribution and reducing the concrete shear strength for shallow wide beams is very conservative in the design process, and does not exist in international codes such as ACI 318- 14 and CSA A23.3-04 that provide the same provisions to design both shallow wide beams and slender beams.
Fiber Reinforced Polymers (FRP) composites are considered an alternative material for strengthening reinforced concrete structures over traditionalmethods,such as using steel plates , steel and/or concrete jacket. FRP are lightweight, non-corrosive, easy to handling and high in tensile strength in spite of the high cost compared with the traditional methods.
This research aims to study simultaneously, the effect of vertical stirrups on the shear behavior of shallow wide beams, as well as the shear behavior of shallow wide beams strengthened in shear with externally bonded CFRP strips.
Based on the results of the experimental work, the contribution of shear reinforcement (vertical stirrups) of shallow wide beams with stirrups is significant and must be taken into consideration when calculating the shear strength of beams, The increase of stirrups volumetric ratio increases the shear capacity of shallow wide beams; Strengtheningusing narrower strips with smaller spacing is better than strengthening using wider strips with bigger spacing for the same CFRP strips volumetric ratio; Removing the CFRP strip with small anchorage length reduces the shear capacity of concrete beams; Increasing the stirrups volumetric ratio in the concrete beams reduces the shear strength due to CFRP strips strengthening; Finally increasing CFRP strips volumetric ratio increases the shear capacity of concrete beams.
Other data
| Title | SHEAR BEHAVIOR OF SHALLOW WIDE BEAMS STRENGTHENED WITH EXTERNALLY BONDED CFRP STRIPS | Other Titles | سلوك الكمرات العريضة الضحلةالمدعمةخارجياً باستخدام شرائح من البوليمرات المسلحة بألياف الكربونفى القص | Authors | Ahmed Aboul-Ela Mostafa Mohamed | Issue Date | 2016 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.