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Frequently Asked Questions (FAQ)
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AnswerIf there are several similar beams or ribs in the model, you can use the functions "Save Provided Reinforcement as Template" and "Load Reinforcement from Template." It is recommended to design the beams together in one case. You can save the modified reinforcement from one downstand beam and then load it for the other beams.
The descriptions of the reinforcement in the Results navigator are defined as follows:
As,-z (top) :
- Upper longitudinal reinforcement, that is, all longitudinal reinforcement that is above the centroidal axis of the cross-section, see Image 01
As,+z (bottom) :
- Bottom longitudinal reinforcement, that is, all longitudinal reinforcement that is below the centroidal axis of the cross-section
- Total longitudinal reinforcement of the cross-section that is required due to torsion
As,-z (top) + As,T/2 :
- Upper longitudinal reinforcement (see above) plus half of the required longitudinal reinforcement from torsion
As,+z (bottom) + As,T/2 :
- Bottom longitudinal reinforcement (see above) plus half of the required longitudinal reinforcement from torsion
- Stirrup reinforcement from torsion
- Always single-leg, that means: reinforcement content from one leg on one stirrup member
- Resulting from the theoretical assumption of a spiral stirrup reinforcement
- Stirrup reinforcement from shear force
- Two-, three-, or four-leg, that means: reinforcement content from one leg on two, three, or four stirrup members
- Setting the number of legs under stirrup parameters, Window "1.6 Reinforcement", "Stirrups" tab, see Image 02
2*asw,T,stirrup + asw,V,stirrup :
- Total stirrup reinforcement from torsion and shear force
- In this case, two-leg for torsion, therefore Factor 2 before asw,T,stirrup, shear reinforcement according to the setting from Image 02
AnswerIn terms of the consideration of creep and shrinkage, the program concept is as follows: Creep and shrinkage are only considered in RF‑CONCRETE Members if there is a curvature and if the cross-section is cracked. The explanation of this can be found in the manual, see Chapter 220.127.116.11.The concept for determining the longitudinal stiffness is designed for curved components. In the case of pure axial loading, the program is not able to determine the exact deformation in connection with the creep and shrinkage according to the current concept.
While Member 1 is an upstand beam, Member 2 is a downstand beam. This results in a compression axial force for Member 1, and a tensile force for Member 2.
For the concrete design, a compressed cross-section is more favorable than a tensioned cross-section. For comparison purposes, here are the axial forces of the members:
Now, if you deactivate the axial forces for the design in RF‑CONCRETE Members, the result is a required reinforcement that is affine to the moment distribution:
With this setting, you are on the safe side for Member 1, but on the unsafe side for Member 2.
In this case, select the material of the European standard group as there is no separate material standard for Sweden at the moment, see the image.
In this case, you should pay attention to the following steps:
- In Window 2.3 "Required Reinforcement by Point," select the "In Grid Points" option, see Image 01.
- Export the results using the "File" menu → "Export Tables," see Image 02.
The deformation uz,local under the "Serviceability Limit State Design" category only refers to the simplified analytical method. However, in the case of a nonlinear calculation, you can display the deformations in the "Nonlinear Analysis" category for the serviceability limit state by using the "Nodal Displacement ug" entry.
AnswerFirst, you should set the reinforcement layout to "Uniformly surrounding" in the Reinforcement tab in Window 1.4.Then, open one of the result windows to compare the results from RF‑CONCRETE Columns and the comparative calculation (for example, 3.1 Required Reinforcement by Cross-Section). There you can check the location where the calculation deviates or where there are serious differences in the results.The first point to check would be the determination of internal forces according to the second-order analysis. These internal forces are ultimately applied for the cross-section design and may lead to different amounts of reinforcement.With this procedure, you can compare the results step by step and, if necessary, identify different calculation methods.Furthermore, it should be checked in which way the stability analysis was performed in the comparative calculation. RF‑CONCRETE Columns designs columns with the nominal curvature method according to EN 1992‑1‑1. If the comparative calculation was performed with a general nonlinear calculation, it is possible that the different results can be linked to the method of calculation.Furthermore, it should be noted that the nominal curvature method for columns in usual building construction with the slenderness λ ≤ 70 gives relatively good results. In the case of greater slenderness, however, this method becomes inefficient relatively quickly.
The method described in the theoretical background for determining a crack width corresponds to the direct crack width calculation according to DIN EN 1992‑1‑1, 7.3.4.
This method is based on the approach of mean strain according to Equation (7.9). In this theoretical approach, the crack width of primary cracks is only determined. The crack spacing (sr,max) describes the theoretical distance to the next primary crack, and at the same time, it represents the length over which the strain difference is considered and finally the crack width is calculated.
AnswerIf the position of the additional reinforcement is different from the position of the basic reinforcement, a common weighted centroidal axis is determined. This in turn has an influence on the SLS design (for example, Ac,eff).
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Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
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