It’s that time of year when we discuss the analysis and design of T-beams in concrete design class. T-beams look like they sound – the T-shaped sections consist of a top flange of concrete with a rectangular web shape. The sections may be individual T-beams, or a system of slabs and rectangular webs. In terms of analysis and design, the challenge is to determine if the sections behave as rectangular beams or as T-beams. A T-shaped section may need to be evaluated as a rectangular shape if the neutral axis (the border line between tension and compression due to bending) is positioned in the top flange. If the neutral axis is lower in the beam, then the section is to be evaluated as a “true” T-beam.
So lectures on this topic pose a problem: what is the correct way to evaluate a T-beam?
T-beam or not T-beam, that is the question.