In RFEM, it is possible to display the resultant of a section or release. This article explains which part of the sectional area is affected. The easiest way would be to refer the resultant to a cut face of the surface. However, since a section may run through several surfaces with different local coordinate systems, determination by means of a cut face is not possible.
Often in RFEM, only part of a surface must be loaded, not an entire surface. A typical case of this is soil pressure. For this purpose, there is the option of defining free surface loads. They are surface-independent and are displayed in defined coordinate dimensions in the graphic.
Before creating a structural model, every user gives thought to the boundary parameters of the system and how best to represent the model. Special attention should be paid to the orientation of the global coordinate system. In engineering, the global Z‑axis is usually oriented downwards (in the direction of the dead load), while it tends to be upwards in architecture. These differences can often lead to complications during modeling; for example, when you replace global models or DXF layers.
In RFEM and RSTAB, it is possible to move or copy models or parts of the model in a user-defined coordinate system. To use this option, a user-defined coordinate system must be available, of course.
In RFEM 5 and RSTAB 8, you can now create a work plane by simply selecting three points. It is no longer necessary to create a user-defined coordinate system.
Rotation-symmetric structures or structural components are frequently entered in the Cartesian coordinate system. For example, subsequently changing the radius requires some effort, as the coordinates should be recalculated first and then updated for each node.
When modeling a load in RFEM, line loads on surfaces are used very often. This may be a line load directly related to a particular load, or a free line load entered at the start and end coordinates.
In the latest version of RFEM, nodal constraints were implemented. Therefore, you can now connect the nodes in an ideal way. The diaphragm type represents the option to couple nodes in a plane. This option is available not only for the global coordinate system, but also for user-defined coordinate systems.
When defining nodal loads, you can rotate the load using several simple options: ~ Rotation by angle around the global coordinate axes in a specific order, ~ Alignment with a user-defined coordinate system, ~ Direction to a particular node, ~ Alignment by means of two nodes, ~ In the direction of a member/line.
When calculating the surface reinforcement in RF-CONCRETE Surfaces, the result values for both surface sides +/- z are available. If you are unsure which side of a surface is the positive or the negative z side, you can hide the local coordinate system of each surface in the RFEM Project Navigator - Display under "Model" → "Surfaces" → "Surface Axis Systems x,y,z". In the case of complex structures, this can quickly become confusing. Displaying multiple axis systems makes it difficult to recognize the incorrect direction of a surface, for example (see the figure on the top).
It is often necessary to adjust the FE mesh of surface elements to the geometric structure. RFEM provides various options for this. For example, the FE axis can be rotated around a point, aligned in the direction of a point, or oriented to a user-defined coordinate system. Another option is the direction parallel to a line, and in this case in particular, it is possible to enter or select several lines.
The equivalent loads determined in RF-TENDON due to prestress are transferred in RFEM as member loads or as line loads. A member load is used for member types with their own stiffness; a line load is used for member types without their own stiffness. In order to understand which values of the concentrated loads are to be transferred from RF‑TENDON to RFEM, you should use the following display settings: ~ Reference of the loads to the global coordinate system (GCS), ~ Load display: "Point"
In RFEM and RSTAB, you can create nodes not only by means of coordinates, but also by means of existing nodes. You can use the "Node Between Two Points" function to create a node located on an imaginary line connecting two nodes. You can enter the distance as a percentage or according to the relative lengths.
The local coordinate system of a member is particularly important when defining member end releases and member nonlinearities. The definitions follow the orientation of the axes. You can temporarily adjust the visibility of these member axes by means of preselection.