Daily Archives: 17. April 2012

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Parameterized Input in RSTAB and RFEM

Parameterized Input

Parameterized Input

By Frank Sonntag, Dlubal Engineering Software

The parameterized input provides the engineer with a tool to enhance effectiveness. It makes it possible to enter model and load data in such a manner that they depend on particular variables. Those parameters (e.g. length, width, live load etc.) are stored in a list of parameters and can be used in formulas to determine a numerical value. The formulas are handled by the formula editor of RSTAB or RFEM. If a parameter is modified on the parameter list, the numerical values of all formulas that use this parameter are updated. The contingent geometry of the model or the loads are adapted automatically.

If you model e.g. an L section that is connected with an eccentricity to a beam, you have to determine the centroidal distances each time when you optimize this section in order to adjust the eccentricity. This can be automated by applying the formula “GetCSPar(CrossSection(1);”e_y”)” in column E of the list of parameters. The value is the determined automatically from the section data of the specific cross-section.

More about the modeling in RSTAB…

More about the modeling in RFEM…

Simulation of Thermal Strains with Specification of Absolute Temperatures in RSTAB/RFEM

Defining temperature as load

Defining temperature as load

By Andreas Niemeier, Dlubal Engineering Software

The structural analysis programs RSTAB and RFEM are able to simulate a thermal strain of structural components by means of temperature loads. We have subdivided our temperature loads because global changes in the temperature of structural components involve a membrane effect, and because temperature changes in relation to the height of structural components implicate bending effects. Temperature load application is now divided into the following two types.
- Uniform temperature (membrane effect)
- Non-uniform temperature (bending effect)

In particular cases, thermal strains are not described by uniform and non-uniform temperatures but surface temperatures of structural components. That’s why we recommend to recalculate specific surface temperatures as shown in the example below.

Mounting temperature: 20°C
Temperature on top surface of component: 60°C
Temperature on bottom surface of component: 22°C

Uniform temperature:
Tm – mounting temperature = (Tt + Tb) / 2 – mounting temperature = (60°C + 22°C) / 2 – 20°C = 21°C

Non-uniform temperature:
Tt – Tb = 60°C – 22°C = 38°C

More about RSTAB…

More about RFEM…