Bond behaviour of steel plate reinforced concrete beams

This technical note presents an experimental study on the bond behaviour of chequer steel plate reinforcements in concrete members based on the beam-end method. The effects of lozenges of the chequer steel plate, the use of steel bolts, and the thickness of the concrete cover on the bond behaviour are investigated. The experimental program includes five specimens designed as beam-end pullout members. Each specimen is 225 mm wide, 300 mm high and 600 mm long. Stirrups with 80 mm centre-to-centre spacing are used as confinement for all specimens. The first specimen is reinforced with a deformed steel bar whereas the remaining specimens are reinforced with steel plates. All specimens except for the one reinforced with a smooth steel plate failed by pullout accompanied by splitting crack. The lozenges of chequer steel plate increased the ultimate pullout failure load by 80% compared to that of the specimen reinforced with a smooth steel plate. It has also been found that the pullout failure load of a steel plate reinforced concrete member can be significantly affected by the thickness of the concrete cover. Two other significant findings are that the pre-ultimate slippage of a steel plate reinforced concrete member is much less than that of a deformed steel bar reinforced one, and that the post-ultimate behaviour of the former is much more ductile than the latter. Comparisons between the present test results and the earlier test results involving reinforced concrete beams subjected to four-point bending tests suggest that the beam-end method may not be an appropriate method for comparing the bond strength of a chequer steel plate against that of a reinforcing bar.