Deep Beam Design

Deep beams are structural elements loaded as beams in which a significant amount of the load is transferred to the supports by a compression thrust joining the load and the reaction. As a result, the strain distribution is no longer considered linear, and the shear deformations become significant when compared to pure flexure. Floor slabs under horizontal load, short span beams carrying heavy loads, and transfer girders are examples of deep beams.

The program performs the design of a simply supported reinforced concrete rectangular deep beam subjected to a uniformly distributed load and two concentrated loads applied on its top face.

The program is based on the ACI Ultimate Strength Design Method and applies to those flexural members having a clear span to depth ratio of less than 4.0. The flexural reinforcement is designed taking into account the reduced lever arm due to the non-linearity of the strains' distribution.

Input Data

The required input data includes the materials' properties and member dimensions, as well as the applied factored loads, not including self-weight

For the shear reinforcement design, the vertical and horizontal bar size and spacing is needed. The figure to the right schematically shows the required input data.

Example

Consider the simply supported beam having a clear span of 10 ft subject to a distributed factored live load of 146.2 k/ft on top. The beam height is 72 in. and its thickness is 20 in. as shown in the left figure. Design the reinforcement and check the adequacy of the deep beam as per de ACI methodology.

The figure below shows the template of this module with the example data and end results.

Output

Once the input data is entered, the program automatically verifies the adequacy of the design. The output consists basically of three messages indicating the adequacy of the spacing of the proposed reinforcement, and five non-dimensional numbers checking the limitations in section capacity and bar sizes suggested by the building code. All these ratios should not be greater than 1.0.