For the stability verification of members using the equivalent member method, it is necessary to define effective or lateral-torsional buckling lengths in order to determine a critical load for stability failure. In this article an RFEM 6-specific function is presented, by which you can assign an eccentricity to the nodal supports and thus influence the determination of the critical bending moment considered in the stability analysis.
For cross‑laminated structures with large spans, downstand beams or hybrid structures are often used. They can be modeled in RFEM 5 by using surfaces and member cross‑sections. In both structural systems, curved downstand beams are also possible without any problems. In the case of the curved surface, the member is always appropriately generated by means of the automatic member eccentricity with the thickness distance of the surface and the member. The downstand beam can also be connected flexibly by means of a line release.
RF‑/FOUNDATION Pro allows you to check the allowable eccentricity of the soil pressure resultants. According to DIN EN p;1997‑1/NA, this design is to be carried out with characteristic or representative loads.
For structural reasons, it may be necessary for a base plate not to be set centrically on a foundation. Therefore, an eccentric arrangement of the base plate is possible in RF‑/JOINTS Steel - Column Base by entering the parameters for the respective direction in Window 1.4.
If a rib is part of a nonlinear design or is rigidly connected to following walls, a surface should be used for the modeling instead of a member. So that the rib can still be designed as a member, a result member with the correct eccentricity is required, which transforms the surface internal forces into member internal forces.
In order to consider inaccuracies regarding the position of masses in a response spectrum analysis, standards for seismic design specify rules that have to be applied in both the simplified and multi-modal response spectrum analyses. These rules describe the following general procedure: The story mass must be shifted by a certain eccentricity, which results in a torsional moment.
There are two ways to specify eccentric nodal loads in RF-/FE-LTB. First, the nodal load has to be applied in the right direction. Then, you can assign either the resulting torsional moment or the eccentricity.
The eccentric wheel load application of 1/4 of the rail head width has to be considered only for fatigue design from damage class S3 according to DIN EN 1993‑6. An additional input option in detail settings allows you to consider this eccentricity for fatigue design at the ultimate limit state as well. By selecting this option, the design with the eccentric load applied is always considered without regard to the damage class.
When modeling eccentric members with member hinges, RFEM provides the option to assign the hinge to the start or end of the member eccentricity. There is another option for creating and displaying the structural system more precisely in the design.
Starting with version X.05.0018, you can also analyze moment-resistant beam-column connections in RF‑/JOINTS Steel - DSTV. Both single-sided and double-sided connections are possible. In compliance with the DSTV guidelines, the program checks (with respect to the loading) whether the existing column cross‑section is dimensioned sufficiently. Optionally, you can transfer the rotational stiffness and the eccentricity of the connection to RFEM or RSTAB.
In RF-/JOINTS Timber - Steel to Timber, you can consider the eccentricities of a connection during the calculation. The figure shows different internal forces without consideration of the eccentricity (above) and withn consideration of the eccentricity (below).