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2023-12-08

Design Situations

The standards describe how the actions are to be combined. EN 1990, for example, requires the design of the ultimate limit state and serviceability limit state, for which certain combination rules apply. ASCE 7 gives specifications for combining load cases for both the strength design and allowable stress design. These limit state rules or design strengths can be analyzed in design situations (DS).

For EN 1990, one ultimate limit state and three serviceability limit state design situations are preset; for ASCE 7, two design situations are preset for "strength design" and "allowable stress design".

The Active check box controls whether the design case selected in the list is analyzed during calculation. This way, you can exclude design situations from the calculation that are not relevant for the model.

Info

Use the New button below the 'List' to add a new design situation.

Main

The Main tab manages the general specifications of the design situation selected in the "List" to the left.

Settings

The "Design situation type" determines the specification according to which the load cases are combined in the superposition. The options are aligned with the standard (see the figure above).

Use the Info button to check the combination rules of the design situation.

Options

Define the combination wizard that is to be used for superimposing the load cases. By default, RFEM creates load combinations that are calculated according to the second-order analysis. The combination wizards are described in the Combination Wizards chapter.

The Consider inclusive/exclusive load cases check box provides the possibility to apply mutual dependencies between load cases. You can define the criteria in a separate dialog box (see the Load Case Relations chapter).

Info

Load cases of the "Wind" action category are generally applied as acting alternatively. You do not need to define any mutual conditions for exclusion.

Overview

The Overview tab lists all load combinations of the design situation, including partial safety and combination factors. Thus, a design situation corresponds to an envelope that includes the most unfavorable constellations of all contained load combinations.

Info

The overview is displayed as soon as the load combinations are generated. To do this, click the "Action Combinations" and "Load Combinations" tabs one after the other.