Performance Assessment of Construction Joints in Reinforced Concrete T-Beams

Abstract

Six reinforced-concrete T-beams were tested under monotonic three-point bending to compare construction-joint configurations. Each specimen had a 200 mm wide, 50 mm thick flange, a 100 mm wide, 150 mm deep web, an overall length of 1200 mm and an effective span of 1000 mm. One monolithic reference beam was compared with two horizontal-joint specimens and three specimens with vertical, inclined or keyed midspan joints. Measured responses comprised first-visible-crack load, ultimate load and midspan deflection, supplemented by visual crack observations. Relative to the 56 kN reference capacity, the horizontal-joint specimens reached 50 kN, a 10.7% reduction; the keyed specimen reached 55 kN, a 1.8% reduction. At the common 30 kN comparison load, the keyed specimen retained 93.5% of the reference secant stiffness. All three deflection checkpoints exceeded first-visible-crack loads and do not establish uncracked stiffness. With one specimen per configuration and no direct interface-slip or reinforcement-strain measurements, these findings are descriptive comparisons of measured global responses. They do not establish statistical equivalence, isolate force-transfer mechanisms or provide general design rules.