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001437
Stine Effler, M.Sc.
2019-11-26

Accidental Torsion in RF-/DYNAM Pro – Equivalent Loads

In the RF‑/DYNAM Pro - Equivalent Loads add-on module, it is possible to consider accidental torsional actions. Which calculation approach is behind the calculation? Which values have to be entered for the eccentricities eX and eY?

Answer:

Accidental torsion is given in EN 1998‑1 Sect. 4.3., ASCE 7‑16 Sect. 12.8.4.2, and NBC 2015 Sect. 4.1.8.12 (4). The eccentricities are to be determined manually; in EN 1998‑1, they are given as 5% of the building length. In other international seismic standards, the principle of accidental torsion is regulated similarly, but the determination of the eccentricities may differ.

For each equivalent load (at each FE node/internal node), a torsional moment is determined according to the following formula:

M = | Fx · ey | + | Fy · ex |
Determination of Torsional Moment

The exported load cases are then output in duplicate number - with the torsional moment M rotating around the vertical axis, once in the positive and once in the negative direction of rotation.

Accidental Torsional Actions
Accidental Torsional Actions
Author

Ms. Effler is responsible for the development of products for dynamic analysis and provides technical support for our customers.

References
  1. Dlubal Software. (2020). Manual RF-DYNAM Pro. Tiefenbach: Dlubal Software.
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