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Frequently Asked Questions (FAQ)
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AnswerNo, no basic reinforcement defined in RF-CONCRETE Surfaces is considered in the determination of internal forces in RFEM. In RFEM, the internal forces are determined with the modulus of elasticity of the selected concrete. The reinforcement amount has no influence (linear-elastic calculation, state I).The situation is different if you perform a nonlinear design in the serviceability limit state state II with the RF-CONCRETE NL add-on module. Here, you specify an available basic reinforcement that you want to consider for the nonlinear calculation in state II. In nonlinear design (available only for SLS), the determination of internal forces is carried out with the effective stiffnesses (state II). Thus, the defined reinforcement has an influence on the internal forces.You can evaluate these internal forces (from state II with the influence of the defined reinforcement) in the results of RF-CONCRETE Surfaces. See Figure 01 with the Results navigator of the RF-CONCRETE Surfaces add-on module.
AnswerFor volumes, we do not provide any internal forces in the program. The conversion of the Spannnugnen in internal forces would be very complex, since not only mx, my and mz would be present, but also the parts of the drill, mxy, myz, mxz also lateral forces and normal forces. With volume one limits oneself usually on a direct voltage evaluation. If you still need internal forces, you have the option to apply the internal forces of the volume to a rod. For this purpose the result bar was implemented in the program.
AnswerPlease double check if you have released the correct elements and the correct amount of elements. If you have only 2 beams connected to each other, please make sure you have released only one of them.
AnswerThis depends on the choice of model type. In this case a flat system was chosen. Thus, only for this level, the relevant results are displayed because they are reduced because of the limited coordinates and degrees of freedom. If, on the other hand, a 3D system is selected as the model type, all stresses and internal forces are displayed.
AnswerTherefore, the surface to the right in Figure 1 is replaced by a moment in the area of the column because the surface is rigidly connected to the column (the surface itself has no line hinge). If you want to exclude this moment, you would have to create an additional line hinge for the right surface or provide the column with a member hinge.
AnswerIn RSTAB, it is also possible to determine plastic internal forces. To do this, you have to select a plastic hinge as nonlinearity by using the member properties (see Figure 1). However, this does not include an interaction of the plastic internal forces. Another possibility is to set releases with nonlinear properties directly. However, you have to use this method to estimate beforehand where these joints form.RFEM provides the option to select a corresponding material model (see Figure 2).
AnswerIf you want to see the results of the edges of a surface, then you can view the results of the line by right-clicking.
If a staff is on the line, you must hide it first. The easiest way is probably to see all the bars in the Show Navigator> Disable model data.
AnswerThe reason for the occurrence of a bending moment in the oblique and straight bar is that the middle post has a certain flexibility due to its finite rigidity. Thus, compression takes place at the middle support, so that the deformation of the middle support also affects the right-hand latch. Because the right-hand latch is additionally held on a movable support, a forced moment arises at this point.One recognizes it above all by the respective deformations. See alsoThe calculation by means of RFEM results in minimum bending moments, which however are not taken into account in the manual calculation.
AnswerWhen creating result bars, make sure that the Results on result members option is selected in the Display navigator. If it is deactivated, no internal forces are displayed.
The following points should be taken into account so that the calculated internal forces can be used for the design:
The model should reflect the real structure as accurately as possible. For this purpose, materials, surface thicknesses, cross-sectional dimensions, joint definitions, support conditions, etc. must be defined correctly.
The loads must be defined and applied in accordance with standards. The combinatorics can be automatically adopted by RFEM.
For internal forces of result combinations, attention must be paid to the evaluation of the correct max / min values. The maximum compressive force in a column corresponds to the minimum normal force (min N).
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