Improvement of the behavior of reinforced concrete beams subjected to torsion

Torsion can be a significant action in many structural members that are part ofcivil engineering infrastructure. Curved bridges, spiral stair cases, eccentrically loadedbox girder bridges, cantilevered slabs and spandrel beams under gravity loads exhibittorsional forces. Most of the recent researches study the behavior of fiber reinforcedpolymer (FRP) strengthened reinforced concrete beams subjected to torsional loads.Many analytical and experimental methods were introduced for evaluation of thetorsional capacity of FRP, but developing the common method of reinforcement(longitudinal or transverse) to improve the torsional resistance of RC structuralelements had paid less attention, hence comes the importance of this thesis which offera new technique of reinforcing RC beams so that to over come the cease of additionalloads resistance.This technique based on nsmg the capacity of RC elements subjected totorsional loading which develops shear stresses by using transverse in differentconfiguration, the shape of the stirrups was ellipsoidal and spiral. The effect of otherparameters such as variation in longitudinal steel amount and fiber addition was alsoinvestigated.The main objective of this study is to give better understanding of the torsionalbehavior of rectangular reinforced concrete beams reinforced with different transversesteel configurations.The experimental program involves testing twenty one reinforced concrete beamswith Rectangular cross section to study their torsional behavior. Three beams were keptas control beams. The rest of the twenty one beams were divided into six groups.Groups (G 1, G2 and G3), contains three beams each, of ellipsoidal, spiral stirrupsconfiguration and different longitudinal reinforcement amount respectively. Groups(G4, G5 and G6) identical to the previous groups in -addition to this certain volumepercentage of polypropylene fiber were added to concrete mixture.The most important variables studied in this research were different transversescheme, longitudinal reinforcement amount and the addition of polypropylene fiber tothe mixture. The beams dimension and surface preparation were nearly identical. Allbeams were tested under identical loading condition. During the tests, cracking loads,ultimate torsional loads and angle of twist were measured.