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.
Surfaces in building models can be of many different sizes and shapes. All surfaces can be considered in RFEM 6 because the program allows to define different materials and thicknesses as well as surfaces with different stiffness and geometry types. This article focuses on four of these surface types: rotated, trimmed, without thickness, and load transfer.
Line releases are special objects in RFEM 6 that allow structural decoupling of objects connected to a line. They are mostly used to decouple two surfaces that are not rigidly connected or transferring only compressive forces at the common boundary line. By defining a line release, a new line is generated at the same place which transfers only the locked degrees of freedom. This article will show the definition of line releases in a practical example.
You can use the stand-alone program RSECTION to determine the section properties for any thin-walled and massive cross-sections, as well as to perform a stress analysis. The previous Knowledge Base article titled "Graphical/Tabular Creation of User-defined Cross-sections in RSECTION 1" discussed the basis of defining cross-sections in the program. This article, on the other hand, is a summary of how to determine the section properties and perform a stress analysis.
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.
In RFEM, RSTAB, and SHAPE-THIN, you can create user-defined print templates ("Printout Report Template") and printout headers ("Report Headers"). These templates can also be transferred to other computers and used there.
The RF‑/STEEL EC3 add-on module automatically transfers the buckling line to be used for the flexural buckling analysis for a cross-section from the cross-section properties. The assignment of the buckling line can be adjusted manually in the module input for general cross-sections in particular, as well as for special cases.
In this article, we will look at the design of shear connectors of cross‑laminated timber structures that transfer the longitudinal forces of the shear wall to the soil.
Usually, the lifting forces acting on a structure, which mostly result from wind loads or a dynamic analysis, are transferred into the ground through ties.
Concrete on its own is characterized by its compressive strength. An important part of reinforced concrete is reinforcing steel, which contributes to both the compressive and the tension resistance of the concrete. Welded wire fabric is generally located in the tension areas of the beams or surface elements (hollow core ceiling, wall, shell) to transfer the tensile forces induced by external loading.
In RFEM and RSTAB, it is possible to define nonlinear properties of member releases. In addition to the activity diagrams and force-deformation relationship, you also have the simple option of using signs or limit values of the internal forces as criteria for the effectiveness of the release. This way, you can specify which internal forces should be transferred at the member end.
When modeling frame structures, RFEM and RSTAB provide various options for controlling the transfer of internal forces and moments at the connection points of members. You can use the member types to determine whether only forces act on the connected members, or whether moments act on them as well. In addition, you can use hinges to exclude specific internal forces from the transfer. One special form is scissor hinges, which allow for realistic modeling of roof structures, for example.
Computer technology has a firm grip on digital structural analysis and design. With each new development, the planners involved are able to increase the limits of what is feasible.
Pay particular attention to the connection points of members and surfaces when you deal with mixed systems, because not all internal forces can always be transferred without difficulty at the coupling location.
When you perform the subsequent modeling of a beam under an existing floor, the first issues that arise are which forces should be transferred between the downstand beam and the floor, and whether a composite effect is the goal. In this case, the floor should rest on the downstand beam without a composite.
When introducing and transferring horizontal loads such as wind or seismic loads, increasing difficulties arise in 3D models. To avoid such issues, some standards (for example, ASCE 7, NBC) require the simplification of the model using diaphragms that distribute the horizontal loads to structural components transferring loads, but cannot transfer bending themselves (called "Diaphragm").
Printout reports created in RFEM and RSTAB can be transferred to VCmaster using a direct interface and further processed there. VCmaster (formerly BauText) is a word processing program for engineers. Calculations, drawings, photos, and documents from various sources can be easily compiled, managed and used again with VCmaster.
In order to ensure the effects of panels, which should act as tensile or compression chords, it is necessary to connect them to the web in a shear-resistant manner. This connection is obtained in a similar way as the shear transfer in the joint between concreting sections by using the interaction between compressive struts and ties. In order to ensure the shear resistance, it must be verified that the compressive strut resistance is given and the tie force can be absorbed by the transverse reinforcement.
Part 4.1 of this article series describes the connection of the RF‑/STEEL EC3 add‑on module; the members and load combinations to be designed were already defined. This section will focus on the optimization of cross‑sections in the module and the transfer to RFEM. The elements already explained in the previous parts are not described again.
In the construction process, it is often necessary to fabricate the concrete elements in sections. A classic example of this production in sections is the use of prefabricated downstand beams, in which the slab is completed in the onsite concrete construction. By creating a new concrete area, interfaces may arise between the already hardened concrete and the fresh concrete. The transfer of the longitudinal shear forces arising between the partial cross-sections must be considered in the design.
If a bending load of a brittle beam element (an unreinforced concrete beam) is increased by means of the bending capacity, the structure responds by breaking the cross-section and the member is separated into two segments. At the time of the failure, the broken part suddenly loses its potential to transfer the bending moment. Due to the segmentation, the critical part also fails to transfer the other force types, such as axial forces.
RFEM and RSTAB provide the option to create national annexes with user-defined partial safety factors and combination coefficients. They can also be transferred to other computers.
Some compound beam structures, such as stacked containers or retracted telescopic bars, transfer the forces in the connection between the components by friction. The load-bearing capacity of such a connection depends on the effective axial force perpendicular to the friction plane and on the friction coefficients between both friction surfaces. For example, the more the friction surfaces are compressed, the more horizontal shear force can be transferred by the friction surfaces (static friction).
The Time Course Monitor displays the results of a time history analysis from RF‑/DYNAM Pro – Forced Vibrations. The graphic can be adjusted in the settings. This can be reached by right-clicking in the shortcut menu. For example, you can activate or deactivate the grid in the graphic. These changes are transferred to the printout report when you print.
The Master's Thesis of Tamás Drávai, Haroon Khalyar, and Gábor Nagy deals with the effect of interoperability between Computer Aided Design (CAD) and Finite Element Modeling (FEM) software on structural modeling and analysis. Several case studies were conducted, where a building information model was transferred from CAD to FEM software with different data exchange formats.
For the superposition or combination of loads, the German standard DIN 18008 refers to DIN 1055‑100. This also applies for the individual parameters of climatic loads to be transferred. In this case, it is possible to summarize the temperature change and meteorological pressure change in a single load and to define the local altitude change as a permanent load.
In RFEM and RSTAB, several interfaces are available. The DSTV interface (*.stp) is the most convenient for importing beam structures, since supports, hinges, loads, and load combinations are also transferred, in addition to the general topology.
In order to increase the stiffness of a ceiling structure in case of renovation, visible downstand beams are used that are not connected to the ceiling structure. Nonlinear line releases can be used to transfer only the compression forces. If there are tensile forces between the ceiling and the downstand beam, as shown in the figure, the downstand beam does not transfer the stiffness in the overall structure.
In a plate with full torsional stiffness, a significant part of the loads is transferred by torsional moments. If it is impossible to set the positive effect of this additional stiffness in the calculation (for example, due to a butt joint of a precast plate in the stiffness area), you have to reduce the torsional stiffness.