Inverted-T Beams: Experiments and Strut-and-Tie Modeling

摘要

Contrary to rectangular deep beams, inverted-T beams are loaded on a ledge at the bottom chord of the beam. This loading configuration induces a tension field into the web and the resulting complex strain distribution renders sectional design provisions inadequate. The applicability of strut-and-tie modeling (STM), developed for rectangular deep beams and simpler, two-dimensional designs, was evaluated. An experimental study was conducted in which 33 tests were performed on 22 large-scale reinforced concrete inverted-T beams and the effects of the following variables were investigated: ledge geometry, quantity of web reinforcement, number of point loads, member depth, and shear span-depth ratio. It was concluded that strut-and-tie modeling, although developed for much simpler structural components, offers a simple and accurate design method for the more complex strain distributions in inverted-T beams. The STM provisions developed for rectangular beams accurately captured both failure mode and ultimate capacity and are recommended for use in inverted-T beam design, as a major conclusion of this research.