Abstract
In this research, results of an experimental investigation on the shear strengthening of lightweight aggregate reinforced concrete deep beams are presented. A total of eight lightweight aggregate deep beams were cast and tested in the experimental work to study the effect of externally bonded CFRP strips in improving their structural behavior, one of them was unstrengthened to serve as a control beam while the remaining seven beams were strengthened in different orientation, spacing and number of layers of CFRP. The locally available natural porcelanite rocks are used to seek the possibility of producing structural lightweight aggregate concrete. The beams were designed to satisfy the requirements of ACI 318M- 14 building code. Results show that the CFRP strips have increased the load carrying capacity for the strengthened deep beams up to 50 % when comparedto the unstrenghtened control one. The diagonal compression strut crack of unstrenghtened control beam is changed to several diagonal cracks in the mid-depth within the shear span of the strengthened beams and exhibited more ductile failure modes. The results also indicate that bonded CFRP system in the shear span was seen to delay the formation of diagonal shear cracks and provided positive restraint to the subsequent growth of cracks. Increasing the amount of CFRP (by increasing the number of layers from one to two layers) results in increase in the ultimate load by about 15%. However, the increase in the spacing between the strips (from 100 to 150mm) led to a decrease in the ultimate load by about 13%.
Highlights
Reinforced concrete deep beams are used as load distributing structural units like transfer Girderswhich are used in multistory buildings to provide column offsets or as horizontal diaphragms, pile caps, foundation walls, and offshore structures
The first shear cracks appeared at approximately about (16 to 35%) of ultimate loads followed by long and slightly wide cracks that developed in the shear span zone with further increasing of the loads
The following conclusion could be made based on the experimental results: 1. The use of carbon fiber strips (CFRP) strips in the strengthening lightweight aggregate deep beams increases the load carrying capacity by about 45% for the present work
Summary
Reinforced concrete deep beams are used as load distributing structural units like transfer Girderswhich are used in multistory buildings to provide column offsets or as horizontal diaphragms, pile caps, foundation walls, and offshore structures. After inclined cracks formulation in deep beam, it takes on a tied arch behavior, allowing the forces to transfer directly to the supports [3] Such behavior provides some reserve shear capacity in deep beams which is not found in shallower members. The shear resistance of reinforced concrete beams can be enhanced by externally bonding FRP composite materials. AligningFRP fibers transverse to the axis of the member or perpendicular to the shear cracks paths is more effective in providing additional shear strength [10] This is achieved by the use of inclined strips. Total wrap is not practical from constructability standpoint in the case of beam applications (where an integral slab makes it impractical to completely wrap the member). the shear strength could be improved by wrapping the FRP system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
