In addition to our technical support (e.g. via email, chat), we also offer an extensive range of free online services available 24/7 on our website.
Frequently Asked Questions (FAQ)
Customer Support 24/7
A taper describes a member or a surface with a variable cross-section. The cross-section type must be consistent, for example, I-shaped cross-sections at both member ends.
In our example, we have a member with a PRO cross-section and a QRO cross-section.
To create a tapered member here, you should use a parametric cross-section for the member start and end:
This allows you to calculate the tapered member.
Temperature-dependent stress-strain properties of an elastic isotropic material can be defined in a diagram or imported from [Excel]. These properties are considered for member and surface elements subjected to thermal load (changes or differences in temperature).
The Reference temperature defines stiffnesses for the members or surfaces that have no temperature loads. For example, if a reference temperature of 300 °C is set, the reduced elastic modulus of this point of the temperature curve is applied to all members and surfaces.
The Options dialog section allows you to control if the Poisson's ratios that are applied to the complete temperature diagram are identical. Clear the check box to access the Poisson's Ratio table column for individual entries.
You have to select and define the Temperature/Modulus diagram by your own.
AnswerThere are two options for defining the failure:
- Assignment of member nonlinearity
For the member types "Beam" and "Rigid", you can define a member nonlinearity for each member. You can find the corresponding option in the "Settings" tab (see Figure 01).
- Assignment of nonlinear member hinges
Alternatively, you can define a member end hinge with failure criterion for the member. For the desired degree of freedom, you can assign the hinge condition with nonlinearity accordingly (see Figure 02).
- Assignment of member nonlinearity
Line supports are only intended for the lines that belong to a surface. For the support of members along their line, it is necessary to define member foundations (also applies to RSTAB), see the figure.
In this case, the following options are available:
1) Corresponding division of the beam (right-click Member → Divide Member) and set the parameterization in the way that there is only one central hole for one of the beams, see Figure 01.
2) Generating surfaces from the member (right-click Member → Generate Surfaces from Member), inserting a circular opening, defining a result beam, see Figure 02.
The load within this area is not taken into account, which can be clearly seen in the example in Figure 01. Here, a homogeneous temperature load (Tc only) was applied, which leads to stress peaks, although the surface can freely strain.
If it is important to consider the load, you can also model the support manually. To do this, simply create an opening of the size of the column and create a new surface corresponding to the surrounding surface (see Figure 02). The values for the spring stiffnesses can be found in the dialog box (see Figure 03).
A surface loaded in this way is then also without stress in the case of a temperature load, as shown in Figure 04.
The cross-sections of members are always related to the centroidal axis in RFEM/RSTAB. The rendering is adjusted accordingly. This has no influence on the calculation.
The factors for the effective lengths are transferred by using the interface for the member (IMember), which is called SetEffectiveLengths(). Use GetEffectiveLengths() to read out the data:// get interface to running RFEM application.iApp = Marshal.GetActiveObject("RFEM5.Application") as IApplication;iApp.LockLicense();// get interface to active RFEM model.iModel = iApp.GetActiveModel();// get interface to model data.IModelData2 iModData = iModel.GetModelData() as IModelData2;// get interface to member 1IMember iMem = iModData.GetMember(1, ItemAt.AtNo);MemberEffectiveLengths memEffLen = iMem.GetEffectiveLengths();memEffLen.No = 1;memEffLen.CheckBucklingLoad = true;memEffLen.Enabled = true;memEffLen.FactorU = 1.1;memEffLen.FactorV = 1.2;memEffLen.FactorY = 1.3;memEffLen.FactorZ = 1.4;// set new effective lengths dataiModData.PrepareModification();iMem.SetEffectiveLengths(memEffLen);iModData.FinishModification();
Please note that it is only possible to read out the properties for the effective lengths (for example, EffectiveLengthY) of the MemberEffectiveLengths structure and the CriticalBucklingLoad property.
Since the boundary surfaces of contact solids can only be of the Null Surface type, it is necessary to model additional surfaces with a section. The following is an example for this.
There is a reinforcement of a plate with an additional plate. Both plates are connected by means of a contact solid:
In order to simulate a weld, borders are required on both plates:
You can simply create the bottom border by inserting a new rectangular surface. In this case, the program asks whether the surface should be integrated into the base surface, which must be confirmed by clicking Yes. There are then two openings in the bottom surface; one in the outermost surface where lies the surface for the border, and another in the surface for the border where lies the bottom surface of the contact solid:
For the upper border, it is also necessary to create a new surface, and the opening to the upper surface of the contact solid must be inserted manually:
After creating the borders, you can insert the actual surfaces for the weld:
If the reinforcing plate is subjected to tension now, the modeled weld transfers the tension stresses:
Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you for the valuable information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”