Load – Deflection relationship of graded concrete beam on different cross-sectional dimension ratio and reinforcement ratio

Abstract

Graded concrete technology could be the best solution to promote the green building concept in the construction industry. The failure behaviour and flexural strength of a RC beam are influenced by various factors, including beam dimension, number and arrangement of reinforcement bars, the shape of the beam cross-section, properties of steel and concrete, and beam span ratio. In this research, the researchers intend to conduct further studies related to the behaviour of graded concrete (GC) beam using various cross-sectional dimension ratios and rebar ratios. This study used 8 (eight) GC beam specimens which mainly made of two concrete mixes, namely the concrete strength of 40 MPa and 20 MPa. The cross-sectional dimension ratio used is 2/3 and 1/2. Two types of rebar ratios were examined which are minimum rebar ratio (0.35% and 0.45%) and maximum rebar ratio (1.59% and 4.78%). The flexural test was carried out by the four-point bending method. The results show that the change in cross-sectional dimensions from 2/3 to 1/2 increases the ultimate load capacity to 62.47% and the deflection decreases to 48.72%. Furthermore, the change of rebar ratio increases load-carrying capacity up to 118.59% and decreases the deflection up to 52.40% along with the increase in the rebar ratio. In the future, it is recommended to design a GC beam using a ratio of 1/2 in cross-sectional dimensions and using a minimum rebar ratio with the respect to the higher concrete strength as the reference.