The structural analysis software RFEM 6 is the basis of a modular software system. The main program RFEM 6 is used to define structures, materials, and loads of planar and spatial structural systems consisting of plates, walls, shells, and members. The program also allows you to create combined structures as well as to model solid and contact elements.
RSTAB 9 is a powerful analysis and design software for 3D beam, frame, or truss structure calculations, reflecting the current state of the art and helping structural engineers meet requirements in modern civil engineering.
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The ASCE 7-22 standard provides several types of design spectra. In this FAQ, we would like to focus on the following two design spectra:
The two-period spectrum is implemented in the program as usual. However, based on the data available from the standard, only the horizontal design spectrum / MCER spectrum as well as the modification related to the force and displacement can be offered.
For the multi-period design spectrum, discrete numerical values are specified. ASCE 7‑22 states that these values can be queried on the USGS Seismic Design Geodatabase page. In the current state of development, you have the option to create a user-defined response spectrum with a g‑factor (depending on the mass conversion constant) to use the data from the ASCE 7 Hazard Tool [1], for example.
Please proceed as follows:
All members when using the Design Add-ons for serviceability checks are considered supported at the end nodes by default. If the member is instead a cantilever or includes an internal support for a combination of both a cantilever and supported at both ends member type, a new Design Support should be defined under the member details.
The Design Support option can be found under the member dialog box under Design Supports & Deflection tab. Supports can be added to any nodes detected along the member length such as the member start, member end, or internal nodes.
Under the New Design Support dialog box, you can set the type of support from the drop-down including general, concrete, or timber. The "general" will give the program guidance on the deflection member type and which limiting deflection ratio to reference from the Serviceability Configurations whether cantilever (e.g., L/180) or supported on both ends (e.g., L/360). The alternative types "concrete" and "timber" will also influence the deflection design, but have additional strength design options incorporated such as moment and shear internal force modification for concrete design and a stress perpendicular to grain check for timber design.
For additional detailed information on this new setting in RFEM 6 including a "timber" type design support, refer to the webinar listed below under Links at time 51:05.
Both support forces and loads are assumed for the calculation with warping torsion in the centroid. Accordingly, an asymmetric cross-section would automatically receive torsion; see the image.
The warping of a cross-section can be displayed in the "full mode". For this, it is reasonable to increase the display factor for torsional warping in the control panel; see Image 01.
Furthermore, you can select the value of the local deformation ω [1/m] in the Results navigator; see Image 02.
After activating Torsional Warping in the Base Data, you can define warping springs and warping restraints. For this, select the Transverse Stiffeners option in the "Edit Member" dialog box; see Image 01.
In the "Transverse Stiffener" tab, you can create several transverse member stiffeners and define the necessary parameters using the "New Transverse Member Stiffener" button. For the "End plate" stiffener type, the resulting warp spring is determined automatically; see Image 02.
In addition to other variants, you can also define a rigid warping restraint or user-defined warping spring stiffness under the "Warping restraint" stiffness type.
As an alternative, you can create member transverse stiffeners using the Data navigator or the menu bar "Insert", "Types for Members", "Member Transverse Stiffeners". In this case, you can use the select function in the "New Member Transverse Stiffness" dialog box to assign them to the corresponding members.
In the Effective Length dialog box, you can simply uncheck the "Lateral Torsional Buckling" option to exclude this check in the design add-on.
Releases for warping are at each member end by default. Splitting members leads to a warping release.
If you do not want to have a warping release there, but rather continuous warping, you need to define a member set. When activating the "Torsional Warping" add-on, the warping is transferred automatically. If this is not desired for the member set, select the "Discontinuous torsional warping" option; see the image.
To perform an earthquake analysis, you need a modal analysis and then a load case of the Response Spectrum Analysis type.
After you have performed your modal analysis, create a new load case. Here you will find the usual settings from the previous program generation.
In the Response Spectrum tab, you can define your response spectrum as usual. If you want to use a response spectrum according to the standard, make sure that the desired standard is selected in the general data of Standards II.
In the Selection of Modes tab, you can select the mode shapes and filter them, if necessary.
After the load case has been calculated, you obtain the results.
Yes, you can also export the response spectra from RFEM 6 and import them into RFEM 5 as a user-defined response spectrum. Please note that export and import via Excel may also have different columns/descriptions due to different versions.
Export your data in RFEM 6 to Excel.
If you want to import this table directly, you will get an error message. RFEM 5 expects a different worksheet description and two columns only.
As soon as you adjust the name in Excel and delete the column with the frequency results, you will be able to edit the response spectrum in RFEM 5.
The main programs RFEM 6 and RSTAB 9 are distinguished by their clarity. The entire input in the program is set up in such a way that you always obtain a clear result for each calculation task. The design of objects is organized in a similar way. In the input, the program shows the necessary properties for each design object, including the corresponding loads, and outputs a clear result for this object after the analysis.
If you want to determine your own design results for the entire model for different load levels, the "Construction Stages Analysis (CSA)" add-on provides a solution. In addition to the basic simulation of the construction process (the object rise), the program also allows for parallel simulation of models with a constant number of objects. In this special case, the base model is internally juxtaposed several times, and can thus be transferred to the design with different loads.
To do this, proceed as follows: