Determination of Transversal Shear Under Seismic Loads

Technical Article

In RF-/DYNAM Pro - Equivalent Loads, the equivalent seismic loads can be calculated according to different standards. By calculating the equivalent loads for each eigenvalue, it is not directly possible to obtain the transversal shear for each story to perform an analysis afterwards. The following example describes the option to calculate the transversal shear quickly and efficiently.

The result beam is used in RFEM to calculate these values. A seismic analysis is performed to generate equivalent seismic loads for each eigenvalue and direction. The procedure in RF-DYNAM Pro - Equivalent Loads will not be explained in detail here. Additional information is available here.

The calculated equivalent loads are separated for each direction in result combinations. After the dynamic analysis, result beams are generated. The function of the result beam is to integrate all member and surface internal forces in the beam element to obtain the internal forces for the entire structure referred to one beam. Afterwards, it is possible to obtain the shear force for each story in x- and y-direction by checking the shear forces of the result beam. On the outside of the structure, a result beam is generated by copying the columns from the edge.

Figure 01 - Generation of Result Beam

After copying the columns, their settings will be changed by modifying the element type to "Result Beam". It is then possible to make special entries for the result beam, here the integration of the entire internal forces in the result beam.

Figure 02 - Settings of Result Beam

After defining the result beam, the internal forces of the result beam can be analyzed by calculating the structure. The internal forces Vz and Vy are important here for the evaluation. The maximum of the shear force is visible on the bottom side of the result element which takes into account the entire structure.

Figure 03 - Evaluation of Shear Forces

The shear force for each story is always the difference between top and bottom value. For each eigenvalue, shear forces in any y-direction are obtained by means of a 3D structure with eigenvalues in x- and y-direction. In the result combination 1 and 2 are thus transversal shear forces in x- and y-direction. Note: For a regular structure with eigenvaqlues in only one direction, only one shear force for the considered direction will be obtained.


[1]   Eurocode 8: Design of structures for earthquake resistance - Part 1: General rules, seismic actions and rules for buildings; EN 1998‑1:2004/A1:2013


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