Structural FEA Software RFEM 6 | Automatic Generation of Combinations

Standards

The Base Data dialog box includes a wide range of standards and the option to create combinations automatically. The following standards are available:

• EN 1990
• EN 1990 | Timber
• EN 1990 | Cranes
• EN 1990 | Geotechnics
• EN 1990 | Base + Timber
•  EN 15512
• ASCE 7
• ASCE 7 | Timber
• ACI 318
• IBC
• CAN/CSA
• NBCC
• NBCC | Timber
• NBR 8681
• IS 800
• SIA 260
• SIA 260 | Timber
•  BS 5950
• GB 50009
• GB 50068
• GB 50011
• CTE DB-SE
• SANS 10160-1
• NTC
• NTC | Timber

For the European standards (EC), the following National Annexes are available:

• DIN | 2012-08 (Germany)
• CEN | 2010-04 (the European Union)
• BDS | 2013-03 (Bulgaria)
• BS | 2009-06 (the United Kingdom)
• CSN | 2015-05 (the Czech Republic)
• CYS | 2010-06 (Cyprus)
• DK | 2013-09 (Denmark)
• ELOT | 2009-01 (Greece)
• IS | 2010-04 (Ireland)
• LST | 2012-01 (Lithuania)
• LU | 2020-03 (Luxembourg)
• LVS | 2015-01 (Latvia)
• MS | 2010-02 (Malaysia)
• NBN | 2015-05 (Belgium)
• NEN | 2011-12 (the Netherlands)
• NF | 2011-12 (France)
• NP | 2009-12 (Portugal)
• NS | 2016-05 (Norway)
• ÖNORM | 2013-03 (Austria)
• PN | 2010-09 (Poland)
• SFS | 2010-09 (Finland)
• SIST | 2010-08 (Slovenia)
• SR | 2006-10 (Romania)
• SS | 2008-06 (Singapore)
• SS | 2019-01 (Sweden)
• STN | 2010-01 (Slovakia)
• CPM | 2011-11 (Belarus)
• UNE | 2010-07 (Spain)
• UNI | 2010-10 (Italy)

Load Cases and Combinations

In the "Load Cases & Combinations" dialog box, you can create and manage load cases, and generate action and load combinations as well as design situations. You can assign the action categories of the selected standard to the individual load cases. If several loads have been assigned to an action category, they can act simultaneously or alternatively (for example, either wind from the left or wind from the right).

Combination Expressions

For the combination of actions in the ultimate and the serviceability limit state, you can select various design situations according to the standard (e.g. ULS (STR/GEO) - permanent/transient, SLS - quasi-permanent, and others). Furthermore, there is the option to integrate imperfections in the combination and to determine load cases that should not be combined with other load cases (e.g. construction load for roof not combined with snow load).

Accidental Design Situation

The "Accidental" design situation automatically considers accidental actions such as earthquake, explosion loads, collisions, and others. When using German standards, you can select the "Accidental - Snow" design situation to consider the North German Plain automatically as well.

Action Combinations

The actions are automatically superimposed in accordance with the combination expressions and displayed as so-called "action combinations". It is possible to define which action combinations will be eventually used for the generation of load or result combinations. Based on the created action combinations, you can estimate how the combination expressions affect the number of combinations.

Load Combinations

The load cases included in load combinations are added together and then calculated in consideration of the corresponding factors (partial safety and combination factors, coefficients regarding consequence classes, etc.). The load combinations can be created automatically in compliance with the combination expressions of the standard. The calculation can be performed according to the geometrically linear, second-order, or large deformation analysis, or as per the post-critical analysis. Optionally, you can define whether the internal forces should be related to the deformed or non-deformed structure.

Result Combinations

The load cases included in the result combinations are calculated first. Then, the results are superimposed by taking into account the corresponding factors. In the result combinations, you can superimpose the results of load cases, load combinations, as well as other result combinations. Internal forces are added together by default. However, there is the option of a square addition, which is relevant for dynamic analysis.

Modifying Stiffnesses / Considering Initial Deformations

In the individual load cases or combinations, there is the option to modify the stiffnesses of materials, cross-sections, nodal, line and surface supports, as well as member hinges and line hinges for all or selected members. Furthermore, it is possible to consider initial deformations from other load cases or load combinations.