Design of deep beams using strut-and-tie models - Part II: Design recommendations

Based on the findings of Part I of this study, the use of current strut-and-tie modeling provisions of both ACI 318-05 and AASHTO LRFD can lead to an unconservative calculation of nominal capacities for some test specimens. New provisions were developed based on the lower bound to a database of 596 published test results. These new provisions incorporate the effects of strut inclination, concrete strength, geometry of a bottle-shaped strut, and shear reinforcement while increasing levels of conservatism relative to ACI 318 and AASHTO LRFD provisions. The use of the new design method results in unconservative nominal capacities for only 5% of the specimens in the database.