This article will show you the Building Model add-on, which has been enhanced with one important advantage: calculating the center of mass and center of rigidity.
In addition to the predefined models available as blocks in Dlubal Center | Blocks, it is possible to create new blocks and save them in the manner discussed in the Knowledge Base article "Saving Models as Blocks in RFEM 6".
Defining the appropriate effective length is crucial in obtaining the correct member design capacity. For X-bracing that is connected at the center, engineers often wonder if the full end-to-end length of the member shall be used, or whether using half of the length to where the members are connected is sufficient.This article outlines the recommendations given by the AISC and provides an example on how to specify the effective length of the X-braces in RFEM.
In RFEM, you can create screw lines using the "Trajectory" type line. To do this, you need a center line/guide line around which the line can be modeled, as well as a start and end point. Then, you can create a "Trajectory" type line between the start and end points; this initially appears as a straight line.
General thin-walled cross-sections often have asymmetrical geometries. The principal axes of such sections are then not parallel to the horizontally and vertically aligned axes Y and Z. When determining the cross-section properties, the angle α between the center-of-gravity axis y and the principal axis u is determined in addition to the principal axis-related moments of inertia.
For a timber connection as shown in Figure 01, you can take into account the torsional spring rigidity (spring stiffness for rotation) of the connections. You can determine it by means of the slip modulus of the fastener and the polar moment of inertia of the connection.
You can use the "Free Circular Load" option in RFEM to apply a partial uplift force to a cone‑shaped floor slab. It can be defined as linearly variable. The definition of center C and the outer boundary R can be specified easily, using the select function.
The simplest way to model a bolt connection in RFEM 5 is to define a node in the center of a hole, then connect it by means of internal members to the surface.
The beam is resting on the column, and the beam ends at the outer edge of the column. These requirements can be fulfilled easily in an architectural model with solids. In member analysis, simplified line models are used in which center lines meet in a common node. In this article, the influence of member eccentricities on the determination of internal forces is shown on three simple models.
The story drift of a building provides valuable information about its structural behavior under seismic loads. These could cause large horizontal deformations and even instabilities. Some standards, therefore, call for a check of the story drift in its center of gravity. It indicates, for example, if a second-order analysis (P-Δ effect) is necessary.
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.
You may already be familiar with the "Center of Gravity and Info" function, which can be accessed using the shortcut menu of any element. If you want to display this information on several elements consecutively, you have to close the dialog box and open the shortcut menu of the next element over and over again.