Investigation of flexural strength of reinforced concrete beams with geo-grid confinement and with polypropylene additive

One of the fundamental disadvantages of concrete is that the tensile strength can be low enough to be negligible and cracking in the direction of prime tensile stresses is inevitable. In the direction of capacity design principle it is aimed to prevent shear failure in order to ensure a more ductile behavior for the capacity of the reinforced concrete elements. In this context, the use of different confined methods and additives in order to increase the ductility of reinforced concrete elements has taken place in the current literature. One of these methods is the confinement provided by using the geo-grid. However, in the current literature the shear effect of different confined methods and additive materials has not been fully investigated and particularly the bond-slip relationship in the reinforcement bars and consequently the structural performance effect was neglected. In this experimental study, it is aimed to investigate the effect of two different confinement methods (traditional and geo-grid confining) and plastic fibers on the behavior of full-scale reinforced concrete beams. For this purpose, fifteen reinforced concrete beams casted in place were divided into two main groups with two different confining techniques. In the first group, the traditional method was used, while in the second group, the geo-grid confining technique was used. Each of the main groups was then subjected to the experiment in two different spacing of stirrups. The first spacing of stirrups was calculated according to conventional methods for bending break while the second selected spacing of stirrups was the increased spacing of stirrups to examine the shear failure behavior. It has been reached the conclusion that for confining technique, the structural behaviors of reinforced concrete beams provided by using geo-grid material cannot meet the behavior of conventional reinforced concrete beams.