NCHRP project 12-61, simplified shear design of structural concrete members

A new method of shear design was introduced into the U.S. community with the AASHTO LRFD Bridge Design Specifications. This method, which is based on the modified compression field theory, provides a unified approach for the shear design of both prestressed and nonprestressed members, overcomes a number of safety concerns, and enables members to be designed for higher shear stress levels. Unfortunately, this design methodology is perceived by many as being more complex than AASHTO's standard specifications. To address this concern, NCHRP funded Project 12-61, Simplified Shear Design of Structural Concrete Members. The objective of this project was to supplement the full LRFD method for shear design with a simplified procedure that provides a direct solution for transverse and longitudinal reinforcement of concrete structures of common proportions. The research approach was to establish the simplified provisions after a rigorous assessment of the merits and limitations of existing shear design methodologies. This assessment was made by using a large experimental database of shear test results and a shear reinforcement calculator tool, which is used to compare the reinforcement required (ρ_v × f _y) by shear design methods for about 500 design cases that represent the breadth and frequency of structures built in the field.