Having created your combinations you classify them as: Construction Stage, Gravity, Lateral, Seismic, or Vibration Mass.
Note: If generated via the Combinations generator they are classified for you automatically.
Then (where applicable) you indicate whether they are to be checked for strength or service conditions, or both. You also have the option to make any of the combinations inactive.
Construction stage combination (Eurocode)
A Construction Stage load combination is only required for the purpose of designing any composite beams within the model. It is distinguished from other combinations by setting its “Class” to Construction Stage.
Typically this combination would include a loadcase of type “Slab Wet”, (not “Slab Dry”), other loadcases being included in the combination as required.
If you add/remove a load case type from this combination - the factors are defaulted as follows:
Self weight - default Strength factor = 1.35, default Service factor = 1.0
Slab Wet - default Strength factor = 1.35, default Service factor = 1.0
Dead - default Strength factor = 1.35, default Service factor = 1.0
Imposed - default Strength factor = 1.5, default Service factor = 1.0
Note: The Slab Wet loadcase type should not be included in any other combination.
Gravity combination (Eurocode)
These combinations are considered in both the Gravity Sizing and Full Design processes.
They are used in the Gravity Sizing processes as follows:
- Design Concrete (Gravity) - concrete members in the structure are automatically sized (or checked) for the gravity combinations
- Design Steel (Gravity) - steel members in the structure are automatically sized (or checked) for the gravity combinations.
- Design All (Gravity) - all members in the structure are automatically sized (or checked) for the gravity combinations.
They are also used during the Full Design processes as follows:
- Design Concrete (All) - concrete members in the structure are automatically sized (or checked) for the gravity combinations.
- Design Steel (All) - steel members in the structure are automatically sized (or checked) for the gravity combinations.
- Design All (All) - all members in the structure are automatically sized (or checked) for the gravity combinations.
Quasi Permanent SLS Gravity Combination
In order to cater for the quasi-permanent SLS load combination, a gravity combination is permitted to have two SLS sets of factors. The quasi permanent combination is only used for the spacing of reinforcement calculation for RC beams (and nothing else).
Lateral combinations (Eurocodes)
These combinations are not used in the Gravity Sizing processes.
They are used during the Full Design processes as follows:
- Design Concrete (All) - concrete members in the structure are automatically sized (or checked) for the lateral combinations.
- Design Steel (All) - steel members in the structure which have not been set as Gravity Only are automatically sized (or checked) for the lateral combinations.
- Design All (All) - all concrete members and all steel members which have not been set as Gravity Only are automatically sized (or checked) for the lateral combinations.
Seismic Combinations (Eurocode)
Note: Although included in this documentation, these are only available for use in regions where seismic design is required.
These combinations are only considered during the Full Design process. They are not used in the Gravity Sizing process.
Vibration mass combinations (Eurocode)
For vibration analysis, you are required to set up specific “vibration mass” combinations. Provided these combinations are active they are always run through the vibration analysis.
Note: It is always assumed that all loads in the load cases in the combination are converted to mass for vibration analysis. You are permitted to add lumped mass directly to the model.
