DIAGONAL COMPRESSIVE CAPACITY OF REINFORCED CONCRETE BEAMS WITH WIDE STIRRUP SPACING

Abstract

 To promote more widespread use of high-strength concrete (HSC) for the efficient design of reinforced concrete (RC) beams, an experimental investigation on the effect of wide stirrup spacing on the diagonal compressive capacity of HSC beams was performed. The predictive equation for the diagonal compressive capacity of RC beams proposed by the authors was modified to cover the application to RC beams with wide stirrup spacing. Four 590-mm deep I-beams with wide stirrup spacing were tested by three-point bending. The influence of stirrup spacing, stirrup diameter, and the number of stirrup legs was discussed. The results show that the diagonal compressive capac ity linearly decreased with wider stirrup spacing regardless of its diameters when stirrup spacing was narrower than 140 mm; however, the effect of spacing became negligible when stirrup spacing was wider than 140 mm. Even when wide stirrup spacing was used, the diagonal compressive stress did not concentrate on the local area of the specimens and a sufficient confinement effect was achieved by providing two-legged stirrups; the localization of compressive stress on the struts was likewise prevented. Finally, the predictive equation by the authors was modified on the basis of the experimental findings. The modified equation covers the application to RC beams with wide stirrup spacing while maintaining adequate simplicity and precise prediction of the diagonal compressive capacity of RC beams.