Experimental Evaluation of Strut-and-Tie Model of Indeterminate Deep Beam

An experimental study was performed to determine the accuracy of designing a statically indeterminate deep beam with three openings using the strut-and-tie modeling method in accordance with Appendix A of ACI 318-08. In this present study, four strut-and-tie models (STM) were independently developed, to closely match the flow of forces according to a finite element analysis. Four specimens were fabricated based on the associated STM, and confining reinforcement was provided at each load and support point. In all four specimens, the failure load exceeded the factored nominal design strength, demonstrating the conservatism of the STM method. The mode of failure in each specimen was dependent on the stress concentrations revealed in the elastic analysis and the STM chosen for the design.