PENGARUH PENGGUNAAN BAJA RINGAN PROFIL HOLLOW TERHADAP KUAT LENTUR BALOK BETON

Abstract

When a load given to a concrete beam, the upper part of the beam will receiving compressive force, while the bottom holds tensile force. The maximum compressive force in the upper part of the beam gradually decreases to zero at the neutral line and then turns into tensile force that increases to maximum at the bottom fiber of the beam. The bottom part of the concrete below the neutral line does not receive any compressive forces, so it works as a conductor for tensile forces to the reinforcement. This study was intended to determine the effect of inserting hollow steel longitudinally to the tensile area of concrete beams in order to increase the load capacity and reduce the volume of concrete simultaneously. In this study, a one-point pressure test experiment was carried out using a Loading Frame with a sample of 28 days old concrete block with f'c = 21.04 MPa measuring 12cm x 18cm x 250cm. The reinforcement configuration is 4Ø10mm with fy = 450Mpa. The beams are casted in 3 variations consist of 2 samples each, which are normal beams, beams with 4x2 hollow steel profiles, and beams with 4x4 hollow steel profiles. The hollow profile steel was not removed during the test. From laboratory tests, it was found that although the reinforced hollow beam cracked early, the load capacity increased and 7.41% lighter than normal beam. Meanwhile, from the calculation simulation concluded, that to match the strength of hollow beams reinforced with hollow profile steel, solid beams need to be more ductile so that the dimensions need to be enlarged and become more expensive. This indicate that the voids in the tensile area of the beam are economically benefit while the stiffness of the concrete beam remain the same and even increasing flexural strength when a hollow profile steel inserted.