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• ### Is it possible to assign temperatures to members in the RFEM R member 8 8 For example, 350 ° C and at the member end z. Eg have 200 ° C?

This is possible. For this purpose, we select the temperature in the member load and display a random distribution over the depth of the cross-section.
• ### What parameters do I have to fill in, if I want to apply a temperature control load via the COM interface?

To create a temperature load on a bar with the COM interface, simply use a bar load with the following parameters:

T_c corresponds to the constant temperature component and dT to the top and bottom different.
• ### Can orthopedic area loads be defined in RFEM? I would like to load a surface with different temperature loads in each direction.

This can not be implemented in RFEM on the debit side. Optionally, the behavior on the structure side can be mapped via the use of orthotropic surfaces.
• ### When calculating a temperature load case, I get the error message 10419 "The temperature load is ineffective". What can I do?

The thermal expansion coefficient for the material is probably zero. As soon as you change it back to a realistic value, the hint should no longer appear.
• ### I would like to perform a hot design with the EC3 module. Is it possible to intervene in the program so that one can be used instead of the standard temperature curves?

The method according to EC 3 can only be used for the temperature curves from EN 1990-1-2. In addition, with the simplified calculation of the steel temperature in the EC 3-1-2, it is only possible to take into account increasing temperature profiles; a drop in the temperature is not available in this simplified calculation. However, it is also possible to use direct steel temperatures in the program (see Figure 1).
• ### Why do I get no stresses on the top or bottom side of a member loaded with temperature (heating on the top side) if the member has no elastic foundation? Or more specifically, why does the upward curved member (due to heating on the top side) have tension stress on the bottom side if the member has elastic foundation? There must be compression stress on the bottom side.

New FAQ 002536 EN-US Results RFEM RSTAB

The topic can be easily illustrated on a single-span beam. For this, three structural systems are described below. These models are documented in the attached file.

###### System 1

Statically determined system (no foundation), dT = 80 ° on the top side

The member is curved upwards, but is free of stress in itself.

###### System 2a

Like System 1, but with an additional member elastic foundation. The member elastic foundation is entered without a possible failure (nonlinearity).

If you would display the stresses sigma_x of the member for System 2a, you obtain compression on the top side of the member and tension on the bottom side of the member (see Figure 01).

Due to the curvature of the member and the existing member elastic foundation, the contact force p-z occurs, which should prevent the member curvature upwards (see Figure 02).

These contact forces p-z (Figure 02) are caused by the member curvature due to the temperature and the applied member elastic foundation. The illustrated contact forces can be replaced by the member load opposed to the curvature. This is shown in System 2b in the example file.

###### System 2b

The member elastic foundation is removed and a variable member load is entered in the Z-direction.

When comparing the results (for example, deformations u-z) on both System 2a and System 2b, you obtain the results with the same value (see Figure 03).

Moreover, you can also display the stresses sigma_x for both System 2a and System 2b. These have also the same value (see Figure 04).

System 3 should only document the stresses due to the temperature difference on a statically determined system (without foundation).

The results documented in the "single-span beam" example can also be transferred to the surfaces with elastic foundations.

• ### How do I define temperature loads on a composite beam?

FAQ 002383 EN-US General RFEM

The load case temperature is very important in composite construction. We distinguish between the following load cases: heating at the top (by concreting) and heating below. Since a temperature change has to be defined here, the load is defined as delta T. Frequently, a composite beam is modeled by means of an eccentric member that is coupled to a surface. For this, you have to divide the temperature difference between both elements (surface and member). The load on the member is defined as a member load with the temperature difference times the member height divided by the total height of the composite cross-section ($\ triangle T \ times \ frac {h_s} {h_g}$). If the upper fibers of the member are colder than the bottom ones, the value must be defined as negative.
Finally, the remaining temperature difference is applied to the surface. Care must be taken here to define the temperature of the member as T c on the surface and apply the still missing temperature as delta T to the surface.
• ### I would like to define a constant temperature load over the cross-section height. Why it is not possible for this to select the load direction in the local x-direction of the member?

For a constant heating/cooling of the cross-section (membrane component), the load parameter Tc must be defined. This generates the length change along the x-axis automatically. It is not necessary to explicitly select the direction x.

The load parameter ΔT describes the temperature difference from the top side of the member to the bottom side of the member (bending component). This can be defined in the y or z direction.