Torsion Behavior of Steel Fibered High Strength Self Compacting Concrete Beams Reinforced by GFRB Bars

This paper investigates experimentally and analytically the torsion behavior of steel fibered high strength self compacting concrete beams reinforced by GFRP bars. Steel fibered high strength self compacting concrete (SFHSSCC) and GFRP bars became in the recent decades a very important materials in the structural engineering field. The use of GFRP bars to replace steel bars has emerged as one of the many techniques put forward to enhance the corrosion resistance of reinforced concrete structures. High strength concrete and GFRP bars attract designers and architects as it allows improving the durability as well as the esthetics of a construction. One of the trends in SFHSSCC structures is to provide their ductile behavior and additional goal is to limit development and propagation of macro-cracks in the body of SFHSSCC elements. SFHSSCC and GFRP bars are tough, improve the workability, enhance the corrosion resistance of reinforced concrete structures, and demonstrate high residual strengths after appearance of the first crack. Experimental studies were carried out to select effective fiber contents. Three types of volume fraction from hooked shape steel fibers are used in this study, the hooked steel fibers were evaluated in volume fractions ranging between 0.0%, 0.75% and 1.5%. The beams shape is chosen to create the required forces (i.e. torsion and bending moments simultaneously) on the test zone. A total of seven beams were tested, classified into three groups. All beams, have 200cm length, cross section of 10×20cm, longitudinal bottom reinforcement of 3 10, longitudinal top reinforcement of 2Φ10, additional longitudinal steel 1Φ8 in the mid height of each side and closed stirrups equal to 10Φ8/m in the tested zone. Group one is considered as a reference group which is consisted of two beams were casted from ordinary concrete. A beam was reinforced by steel bars and the other was reinforced by GFRP bars. Group two is consisted from two beams were casted from self compacting concrete with steel fibers volume fraction equal to 0.0% and 0.75% and were reinforced by GFRP bars. Group three is consisted from three beams were casted from high strength self compacting concrete with steel fibers volume fraction equal to 0.0, 0.75% and 1.5% and were reinforced by GFRP bars. An analytical study is used formulas from previous studies to model the tested beams and numerical results are validated with the experimental results. It is found that the effect of steel fibered high strength self compacting concrete (SFHSSCC) on the beams reinforced by GFRP bars enhances the ultimate loads under torsion moments. The present work describes the experimental and the numerical research carried out, and presents the main obtained results. Khaled S. Ragab is Associate Professor, Reinforced Concrete Research Institute, Housing & Building National Research Center, HBRC, (Cairo, Egypt ([email protected]). Ahmed S. Eisa is Lecturer,Structural Engineering Department, Faculty of Engineering, Zagazig University, Zagazig, Egypt. ([email protected]). Keywords—Self compacting concrete, torsion behavior, steel fiber, steel fiber reinforced high strength self compacting concrete (SFRHSCC), GFRP bars.