RWIND 2 is a program for generating wind loads based on CFD (Computational Fluid Dynamics). The wind flow numerical simulation is generated around any building, including irregular or unique geometry types, to determine the wind loads on surfaces and members. RWIND 2 can be integrated with RFEM/RSTAB for the structural analysis and design or as a stand-alone application.
Wind blowing parallel to the surfaces of a structure can generate friction forces on these surfaces. This effect is important mainly for very large structures.
Buildings are structures surrounded by wind. The flow around them creates specific loads on the surfaces, which are to be used for the design in structural analysis.
In RFEM, loads can be freely defined on surfaces. It is impossible, however, to define a variable loading on, for example, circular surfaces. However, you can still create this type of loading by using a free circular load.
You can display the results on surfaces in a graphic. It may be useful to use the values on surfaces. Depending on the requirements, you can reduce the number of values considerably or adjust them to cover the entire structure. However, it is important to display the values that represent the local extreme values. In addition, it is necessary to determine the local extremes. This can be done by right-clicking this function in the Navigator.
RFEM provides the option to display up to three result values of the surface results in each group. Four groups are preset under "Groups" in the Results Navigator.
The new "Result Beam" member type in RFEM 5 allows you to determine the load sums of individual floors easily. To do this, model a member in the relevant floor or in all floors, then specify the relevant walls as inclusive objects in the parameters of the result beam. RFEM then integrates the surface internal forces into member internal forces.
The "Result Beam" member type has been available since the release of RFEM 5. The result beam is a virtual member that does not have any stiffness nor require any support. It can be used in various situations in order to integrate the results from members, surfaces, and solids, and to display them as member internal forces.
With the nonlinear elastic material model in RFEM 5, you can calculate and carry out a stress analysis of surfaces and solids with nonlinear material properties.
The "Mapped Mesh Preferred" option has an influence on the mesh generation of surfaces with curved and folded outlines. The program tries to align the FE mesh with the boundary lines of the surfaces.
This article explains the use of surfaces with the Load Transfer stiffness type in RFEM 6. A practical example is also provided to demonstrate the application of self-weight, snow load, and wind load to a steel hall.
When using the wind load generator for vertical walls with a roof, it may be necessary to load the edge members on eaves or on a gable only with the wind loads of the roof. For structural reasons, the horizontal wind loads should apply to the vertical walls by the facade. In previous versions, it was necessary to apply the wind loads separately to the walls and the roof with the corresponding generators and exclude the unwanted members.
The averaged internal forces from the previously defined average regions can also be used for designing concrete surfaces. To do this, click [Details] in RF‑CONCRETE Surfaces, then select the corresponding check box. This function is accessible only if you previously defined an average region.
In order to use internal forces from average regions also for the design of concrete surfaces, you have to activate them in the module. For this, click the [Details] button in the "Tools" tab and select the option "Apply the averaged internal forces in the defined average region for the ULS calculation and for the analytic method of SLS calculation."
In many frame and truss structures, it is no longer sufficient to use a simple member. You often have to consider cross-section weakenings or openings in solid beams. In such cases, you can use the "Surface Model" member type. It can be integrated into the model like any other member and offers all the options of a surface model. The present technical article shows the application of such a member in an existing structural system and describes the integration of member openings.
The data exchange between RFEM 6 and Allplan can be done using various file formats. This article describes the data exchange of a determined surface reinforcement using the ASF interface. This allows you to display the RFEM reinforcement values as level curves or colored reinforcement images in Allplan.
If you want to connect members tangentially to a curved member or a curved surface in RFEM, it is necessary to define the member rotation of the connected members. In order to avoid manual determination, you can display the center point of the curved line and place a node on it. Then, you can select the "Member Rotation via Help node" option and specify the relevant help nodes. Thus, the members are rotated automatically in the defined plane (x-z in our example) and the top edge of the rotated cross-section is parallel to the tangent of the curved line.
RF-PUNCH Pro performs punching shear design on concentrated load application locations (column connection, nodal support, and nodal load) as well as on wall ends and wall corners.
You can color the surfaces in the direction of the local z‑axis using the indicated option in the Display Navigator. By default, the side lying in the negative z-direction is colored red and the side lying in the positive z-direction is colored blue.
In RF-STEEL Surfaces, it is possible to display the stresses relevant for the design of welds, for example, according to EN 1993‑1‑8, Figure 4.5. When evaluating the stress components, the local xyz-axis system of the surfaces must be considered.
In the "Edit Surface" dialog box, there is a new tab titled "Modify Stiffness" for the "Standard" and "Without Tension" surface types. Here, you can modify the elements of a stiffness matrix by defining the factors in the same way as in the case of orthotropic surfaces.
In SHAPE-THIN, the calculation of stiffened buckling panels can be performed according to Section 4.5 of EN 1993-1-5. For stiffened buckling panels, the effective surfaces due to local buckling of the single panels in the plate and in the stiffeners, as well as the effective surfaces from the entire panel buckling of the stiffened entire panel, have to be considered.
When wind-induced surface pressures on a building are available, they can be applied on a structural model in RFEM 6, processed by RWIND 2, and used as wind loads for static analysis in RFEM 6.
A previous article presented different variants of surface elastic foundations in addition to the traditional subgrade reaction modulus method. The following article describes another method for surface foundation. This method considers the adjacent ground areas by means of a foundation overlap. In this case, foundation parameters refer to the continuing works by Pasternak and Barwaschow.
Just as in the RFEM Display Navigator, you can set the distribution of internal forces in surfaces in RF‑STEEL Surfaces. Since deformations are always the result of the FEM calculation, the corresponding forces will be recalculated. This means that the internal forces on an FEM element are calculated depending on the composition (triangular or square) in three or four places. In order to obtain continuous internal forces and thus a smoothed distribution, these internal forces have to be interpolated. Interpolation is done by selecting the "Distribution of internal forces" option in the surfaces.
When calculating a surface model, the internal forces are determined separately for each finite element. Since the element-by-element results usually represent a discontinuous distribution, RFEM performs smoothing of the internal forces that takes into account the influence of adjacent elements. The discontinuous distribution of internal forces is adjusted with this method. The result evaluation is thus clearer and easier.