Design of deep beams using strut-and-tie models - Part I: Evaluating US provisions

From published reports, a database of 596 tests of reinforced concrete beams with shear span-depth ratios less than 2 was assembled. That compilation of data was used to examine the strain energy in various truss models that could be used to model the test specimens. It was found that single direct strut between the load and one of the reaction points was the favored mechanism. The strut-and-tie modeling provisions of AC 1318-05 and AASHTO LRFD were evaluated using the results contained in the database. The results of the analysis indicate that the use of both ACI 318-05 and AASHTO LRFD does not produce levels of safety that meet a 5% exclusion limit.