The effect of polypropylene fiber additive on the overlap length in reinforced concrete beams

In some cases, longitudinal reinforcements within the reinforced concrete structural element are made by adding an overlap length over each other for designing structures. The additional length of the overlapping reinforcements here is called the overlap length. As it is generally used in columns in the specifications, it may be necessary to make the mentioned overlapping in reinforced concrete beams. For this, it is not clear whether the overlap length used for columns in the American Concrete Institute (ACI) specification will be used on the beams. Making the overlap length and design correctly is very important especially in terms of mechanical properties of the structure such as strength and load bearing capacity. If the overlap length is insufficient, stresses intensify at the ends of the reinforcement and in case of a severe jolt, there may be many problems such as early migration in the structure. When fiber additives are added to reinforced concrete carrier elements, the mechanical properties of the structure can be improved and the length of the overlap can be kept short. Fiber additives are used today to obtain a stronger structure with high strength and durability and good mechanical properties. Keeping the overlap length short is also better in terms of applicability, machinability and fabrication. In this study, the effect of plastic fiber additive on the overlap length of reinforced concrete beams has been studied. Within the scope of this study, 11 reinforced concrete beams in size 16/25/150 cm have been designed. The lower and upper boundaries of the overlap length calculated using the equation specified in the ACI specification have been tested by adding plastic fiber admixture at different rates to 11 reinforced concrete beams. In terms of applicability, workability and fabrication, for the reinforced concrete beams with poly-propylene fiber additives, it has been determined that the additional overlap length can be reduced in certain ratios compared to the model proposed in the current literature.