Effect of Detailing of Web Reinforcement on the Behavior of Bottle-shaped Struts

Abstract

The effect of detailing of web reinforcement as per current design codes on the strength and serviceability behavior of bottle-shaped struts has been experimentally investigated, particularly in the context of codal minimum reinforcement requirements, by testing eleven scaled deep beams. The experimentally obtained efficiency factors of the bottle-shaped struts besides being significantly higher than the values given in the ACI 318-08 were also found to be sensitive to the amount of web reinforcement. The minimum web reinforcement requirements specified in current design codes were found to be adequate for controlling service load crack widths though the unreinforced bottle-shaped struts allowed in the ACI code were observed to violate the maximum crack width requirements. It has been shown that the transformation equation in the ACI code does not accurately represent the relationship between the strut efficiency factor and the amount of transverse reinforcement whereas a corrected version of the equation shows a clear dependence of the former on the latter.