Concrete Beams Design

The program performs the design of a non-prestressed T or inverted-T concrete beam when subjected to a combination of bending, torsion and shear loading, based on the latest ACI torsion design criteria and the Ultimate Strength Design Method.

Per ACI, the contribution of concrete to torsional strength (Tc) is disregarded. Thus, Vc is unaffected by the presence of torsion. Design for torsion is based on a thin-walled tube, space truss analogy. The interaction of bending with shear and torsion is accounted for by adding the torsion longitudinal steel to that required by flexure.

Input Data

The required input data consists of the materials' properties, the beam type (either T or inverted-T), the cross section dimensions, the applied factored loads, and the reinforcing bar sizes.

T-beams may be either edge or interior, and inverted-T beams may be easily modeled as L. The input data required by this program is shown in the figure at right.

Example

Design the reinforcement for a 42-ft long spandrel beam in a cast-in-place concrete office building. The beam dimensions are 20" x 32" and is cast monolithically with a 6" thick slab.

The beam is subjected to a shear of 103 k, a bending moment of 837 k-ft, and a torsional moment of 72.5 k-ft. Assume f'c=4,000 psi and fy= 60,000 psi.

Output

When the data is entered, the program automatically performs the computations and shows the analysis results.

Figure above shows the template related to this program with the data of the example.