Properties Tab

The properties tab provides the basic input geometric and material properties associated with the Coupling Beam.

Typical Reinforcing

The Typical Reinforcing tab holds the bar sizes and spacings used for the selected Coupling Beam. The first time the Wall Design Group is designed, the settings here will reflect the global coupling beam design criteria. Within this tab, the reinforcing settings may be changed, and the design rerun. The new settings will affect only the selected coupling beam, not all the coupling beams in the Wall Design Group. To save the new reinforcing settings and the associated design results, select Update Database after running the design. At this point the Coupling Beam will be frozen with the current settings.

The Typical Reinforcing specification consists of one to five top and bottom layers of bars (specified separately) with a designated bar size and number of bars in each layer, as well as the vertical spacing of the bar rows. Additionally, a bar size and nominal spacing for side bars (which are placed at each wall face), and a tie size and spacing transverse to the section, are specified. For the settings in the dialog above, the resulting reinforcement is as shown below.

Alternatively, a uniform reinforcing layout may be specified by selecting the appropriate check box. In this case, the coupling beam will be reinforced as would a wall. The settings in the uniform layout area would govern the placement of the reinforcing.

All of the longitudinal bars (top, bottom, and side) are considered for the axial-flexural strength checks. The transverse bars are considered as the shear reinforcing for the purpose of shear strength calculations. All longitudinal bars are located a distance away from the face of the section equal to the clear cover plus the diameter of the ties.

Diagonal Reinforcing

The diagonal reinforcing tab is available if (and only if) using a design code that has specifications for special diagonal reinforcing for seismic applications. As with the Typical Reinforcing tab, any setting may be changed and the design rerun. The diagonal reinforcing specified here does not affect the placement of the typical reinforcing, even if there are collisions.

Since the location of the diagonal bars in cross section varies along the length of the Coupling Beam, a slider is provided that allows the user to change the view location along the Coupling Beam. This is called the Cross Section View Location, and it input as a fraction of the Coupling Beam span.

Design Results

The Design Results tab holds the axial-flexural and shear results for the selected coupling beam.

Changing the Critical Condition selection will update the design results to reflect the respective condition. The axial and flexure values of both capacity and demand are reported, as well as the corresponding load combination. Two values of interaction ratio are reported: one corresponding to the worst overall interaction, and one corresponding to the currently selected critical condition.

Recall that, as described in Section 2.11, Section Cuts are created at the quarter points within free spans of the header, and thus several locations along the coupling beam are evaluated for axial flexure. Thus, the location at which the selected critical condition occurs is also reported in the Axial-Flexure region. The location is expressed as a distance from either the left face of the beam, or the right face of the beam, depending on the user's selection.