Ehsan Mohsenian Fard; Meysam Memar; Davood Ghaedian
Abstract
Concrete and rebars should have a good bond behavior so that there is no slip between rebars and concrete under the service loads. On the other hand, one of the major disadvantages of steel bars is their vulnerability to corrosion. Covering bars as a solution is also costly and cannot be implemented ...
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Concrete and rebars should have a good bond behavior so that there is no slip between rebars and concrete under the service loads. On the other hand, one of the major disadvantages of steel bars is their vulnerability to corrosion. Covering bars as a solution is also costly and cannot be implemented in all projects. So one of the most suitable alternative methods is the use of GFRP bars. Other ways to compensate for the weakness of the concrete tensile strength as well as its low ductility are the use of different fibers. Concrete with polypropylene fibers is highly ductiled compared to conventional concrete and is completely scattered in concrete and creates isotropetic conditions and can prevent cracks. Therefore, in this study, the effect of polypropylene fibers on concrete compressive strength and bonding strength between concrete and GFRP rebar was investigated experimentally. For this purpose, the amount of this type of fiber is selected 0.15, 0.30 and 0.45 % volume of concrete, and 15cm cubic concrete samples were made in three types of 350, 400 and 450 grade and were cured at 7- and 28-day ages. In this study, the rebar diameter of GFRP was chosen 8 mm and rebars were embedded inside the concrete in a length five times the rebar diameter, and 28-day concrete samples were tested through pull-out and compressive resistance tests. Finally, the compressive strength of the samples and the force-time curves from the pull-out test were assessed. Average compressive strength values, slump values, maximum force and other important parameters were discussed. The results showed that the bond resistance between the polypropylene fiber-reinforced concrete and GFRP rebar increased with the increase in the amount of fibers. Adding fibers also has a relatively good effect on enhancement of the compressive strength of the concrete.
saeed radmanesh; roozbeh aghamajidi
Volume 3, Issue 2 , May 2021, , Pages 32-47
Abstract
Flexural reinforcement of reinforced concrete beams with composite materials is one of the most common methods of structural reinforcement. Composite materials have several advantages such as ease of implementation, easy access, relatively low cost, increased bearing capacity, low weight, etc., but despite ...
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Flexural reinforcement of reinforced concrete beams with composite materials is one of the most common methods of structural reinforcement. Composite materials have several advantages such as ease of implementation, easy access, relatively low cost, increased bearing capacity, low weight, etc., but despite all these advantages, the use of these materials also has disadvantages, which can be Premature and sudden bending failure in beams reinforced with these materials, which occurs due to premature rupture of composite materials or even deterioration of the joint area due to lack of attention to the stability of epoxy adhesive from the concrete surface in the tensile zone of the beam, noted. In this paper, by designing a computational program with Abacus software, 7 examples of reinforced concrete beam reinforcement design with GFRP rebar by near-surface installation method (NSM) and its integration with various FRP sheet enclosure cases taken from a This is a laboratory study, an attempt was made to prevent premature failure of the reinforced beam and to be able to use the maximum capacity of GFRP rebar. It is noteworthy that in modeling this reinforcement design with composite materials, the effect of ultimate adhesion resistance and failure or deterioration of epoxy adhesive between NSM rebar and concrete surface is important, so in this modeling of the joint area which is epoxy adhesive modeling and its behavior Has been examined. The use of this reinforcement method with four NSM rebars and FRP sheets increased the final bearing capacity by more than 60% compared to conventional reinforced concrete beams.
