HIGH-STRENGTH REINFORCED-CONCRETE DEEP AND SHORT BEAMS - SHEAR DESIGNEQUATIONS IN NORTH-AMERICAN AND UK PRACTICE

The use of high-strength concrete deep beams in tall building construc tions is gaining rapid popularity and has begun to outpace the develop ment of appropriate design equations. This paper reviews the shear str ength equations as given in the ACI Building Code, the Canadian Code, and the UK's CIRIA Guide, and shows that the existing CIRIA prediction s may be unconservative for high-strength concrete deep beams. A modif ied form of the CIRIA equation is studied, and its predicted values ar e compared with experimental values, and those calculated from the ACI Building Code, the Canadian Code, and the current CIRIA. The comparis on involves a total of 233 deep beams, out of which 57 specimens were tested in-house. The study shows that the modified CIRIA equation give s the smallest coefficient of variation and standard deviation among t he methods considered. The equation is also applicable for a comparati vely wide range of shear span-to-depth ratios, concrete strengths, mai n steel ratios, and web-reinforcement types.