Design for Shear in Reinforced Concrete Using Strut-and-Tie Models

The design of reinforced concrete members for shear was studied. Both strut-and-tie models (STM) and sectional methods were examined. Initially, the response of isolated struts was observed. Various layout of reinforcement were used within the isolated struts. Three series of deep beam tests were also conducted. The first series was used to examine the effects of load distribution (uniform or concentrated) and distribution of shear reinforcement (horizontal and vertical) on shear strength of deep beams. The effects of beam width and shear span-to-depth ratio on shear strength were studied using the second series of beam tests. In the final series, the effects of load distribution on specimens without shear reinforcement were observed. A database of approximately 1,200 experimental results was compiled. The database, along with the experimental program, was used to evaluate the levels of conservatism of North American STM code provisions as well as sectional design provisions. A new design procedure was developed to improve the safety of STM design procedures. Along with the new procedures, an expression was created to determine the necessary amount of reinforcement within a bottle-shaped strut. Finally, recommendations to improve the conservatism of sectional design provisions were developed.