PERILAKU DAN PENINGKATAN KAPASITAS BALOK TINGGI AKIBAT PERUBAHAN RASIO BENTANG GESER TERHADAP TINGGI EFEKTIF BALOK (a/d)

Abstract

The advantage of deep beam is it has a stiffness factor higher than conventional beam. Design of deep beamreinforced concrete usually just consider minimum reinforcement only, for longitudinal reinforcement and shear reinforcement because deep beam is not designed to received main load but just for esthetic only. Because of that reason, this research is needed to design reinforcement on deep beam for carrying main load so that a premier failure can be avoid. Twelve (12) specimens are used in this research. The compressive strength of the deep-beams is 25 MPa simply supported with the dimensions of (13x40x100) cm such as result from geometric scale 1: 4. The tensile reinforcement is 4 Ø 10 mm and the compressive reinforcement is 2 Ø 10 mm. The shear reinforcement used is Ø 6 – 100 mm for each specimen. Longitudinal shear reinforcement variations used without longitudinal shear reinforcement, 2 Ø 6 mm, 4 Ø 6 mm and 6 Ø 6 mm. For each variations used, there are 3 sample tests. The sample tests are done by using two-point simetrical load and span shear ratio towards effective deep beam (a/d) starting from 0,6 ; 0,8 ; and 1. Data of crackload, ultimate-load, strain of longitudinal reinforcement, strain of shear reinforcement, strain of longitudinal shear reinforcement and displacement of beam on point load is measured for load increase with interval load is 250 kg. The result of the research shows that span shear ratio towards effective deep beam (a/d) can establish shear crack load capacity (Pcr) and ultimate load capacity (Pu) of deep beam. Decreasing of span shear ratio towards effective deep beam (a/d) caused load capacity of deep beam increase. Strain of reinforcement was measured load capacity of deep beam, for Pcr and Pu. Span shear ratio towards effective beam depth (a/d) is influence load capacity of deep beam. So that, increasing span shear ratio towards effective deep beam (a/d) caused strain of longitudinal reinforcement and shear reinforcement decrease. Span shear ratio towards effective deep beam (a/d) also measure behavior of deep beam. At the shorter span shear ratio towards effective deep beam (a/d), failure of deep beam is shear-failure. At the longer span shear ratio towards effective deep beam (a/d), failure of deep beam is tension-failure.