High-strength reinforced concrete deep and short beams: Shear design equations in North American and UK practice

The use of high-strength concrete deep beams in tall building constructions is gaining rapid popularity and has begun to outpace the development of appropriate design equations. This paper reviews the shear strength equations as given in the ACI Building Code, the Canadian Code, and the UK's CIRIA Guide, and shows that the existing CIRIA predictions may be unconservative for high-strength concrete deep beams. A modified form of the CIRIA equation is studied, and its predicted values are compared with experimental values, and those calculated from the ACI Building Code, the Canadian Code, and the current CIRIA. The comparison involves a total of 233 deep beams, out of which 57 specimens were tested in-house. The study shows that the modified CIRIA equation gives the smallest coefficient of variation and standard deviation among the methods considered. The equation is also applicable for a comparatively wide range of shear span-to-depth ratios, concrete strengths, main steel ratios, and web-reinforcement types.