Moment redistribution in reinforced concrete castellated beams with external pre-stressing

Abstract

This paper presents the results of both experimental and numerical investigations on the overall structural performance of two-equal-span reinforced concrete perforated (castellated) beams subjected to external pre-stressing. First, the effects of providing castellated openings along with the application of external pre-stressing on both the ultimate capacity and the percentage of moment redistribution were investigated experimentally. Then, after validation of the numerical modelling, the effects of controlling the parameters on the percentage of moment redistribution were investigated numerically. Experimental results showed that providing castellated openings accelerated the appearance of both flexural and shear cracks, and decreased the ultimate capacity by about 24% compared to that of a solid beam. Moreover, application of external pre-stressing on the castellated beam compensated for the reduction in ultimate capacity and outperformed it by about 9% compared to that of a solid beam. Based on the numerical results, it appears to be better to increase the amount of main tensile steel and strand eccentricity at the hogging moment zone, as well as increase the effective pre-stressing force, to reduce the percentage of moment redistribution at both sagging and hogging moments.