In ConcreteBending, strength level (LRFD) load combinations are required to perform concrete design checks. The analysis results from service level (ASD) load combinations can viewed, but they are not used for design. Several sets of both ASD and LRFD building code load combinations are built into ConcreteBending. Custom load combination sets may also be created.

Custom Load Combinations

Use the Create Factored Combination button located in the Load Case Manager to create any custom combination needed. Custom factored load combinations can be imported from the clipboard using the Import From Clipboard button in the Load Combinations tab in the Load Case Manager. Text must be tab delimited and copied to the clipboard in the following format:

     {ComboName} {Factor} {ServiceCaseName} {Factor} {ServiceCaseName2} …

For example:

     ComboName    1.2    D     1.6    L     0.5    Lr

     MyCombo     0.9    D     1.3    W

Environmental Design

Environmental design in accordance with ACI 350 requires analyzing all service cases with loads in them. Go to the Service Case tab of the Load Case Manager. Select the service cases with loads in them and check Include in Analysis.

Seismic Criteria

In order to correctly generate load combinations that contain seismic loads, several additional parameters are required. Please refer to ASCE 7, Section 12.4, for how these parameters are used in generating load combinations. It is important to note that these parameters (such as SDS and SD1) are only used to generate load combinations. For example, ASCE 7 says that Seismic Category A does not require the combined orthogonal direction combinations (e.g. X+30%Y), but Category D does. ConcreteBending does not automatically generate any loads, just the combination cases.