Title: INVERTED-T BEAMS: EXPERIMENTS AND STRUT-AND-TIE MODELING

Author(s): N. L. Varney, E. Fernández-Gómez, D. B. Garber, W. M. Ghannoum, and O. Bayrak

Publication: Structural Journal

Volume: 112

Issue: 2

Appears on pages(s): 147-156

Keywords: D-region; inverted-T beam; laboratory testing; large-scale; nonlinear design; reinforced concrete; shear; shear span; strut-and-tie.

DOI: 10.14359/51687403

Date: 3/1/2015

Abstract:
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.