12-Storey Building (Patran Plug-in)

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In this tutorial, SFEM analysis of a building model will be performed using the SFEM analysis menu of the plug-in.


Description of the deterministic FE model

In this analysis, a building model consisting of 12 floors will be analysed, for which the FE model is constructed in PATRAN. The floors and walls are modeled with CQUAD shell elements, while the girders have been modeled using BEAM elements. A static loading, as well as the self weight of the building have been considered as Boundary conditions, while the building has been fixed at the bottom nodes of the elements, which model the foundation.


Building model.jpg


Definition of the probabilistic model

For the problem at hand, it is assumed that the effect of the uncertainties within the Young's modulus are to be investigated. For this purpose, five different materials have been modeled within the FE model. These materials are used then to represent the foundation, cellar, floors, inner walls and the girders. Please find below the probabilistic definition for their young's modulus values:


Summary of the Probabilistic Model

Structural Property

Distribution     Mean Value      CoV Value

Young's Modulus (Foundation)

Normal (truncated) 28 GPa 0.10

Young's Modulus (Cellar)

Normal (truncated) 28 GPa 0.10

Young's Modulus (Floor)

Normal (truncated) 32 GPa 0.10

Young's Modulus (Inner Walls)

Normal (truncated) 32 GPa 0.10

Young's Modulus (Beams)

Normal (truncated) 32 GPa 0.10


Performing the SFEM analysis

The SFEM analysis will be performed within the PATRAN preprocessor using the features of the plug-in. Using the SFEM Analysis menu of the plug-in, following GUI will appear:


Sfem gui.jpg


This interface is developed in order to define the necessary parameters within the analysis, as well as to define the probabilistic model for the considered problem. Please note that the plug-in will list all the young's modulus values defined in the FE model automatically. These can be then modified on the GUI. It should be also pointed out that only the young's modulus can be modeled as random using this menu.


Once the method, implementation type and the probabilistic model is defined, the user can proceed with the preparation of the input file by clicking on the ACCEPT button. An input file for the COSSAN engine will be created. The analysis can be started now by the user by clicking on the RUN button.

Results of the SFEM analysis


The estimated statistics of the response obtained using various methods are summarized in the following table:

Summary of Statistics (Node )

Response

   Neumann (100 samples)     P-C Expansion (3.order) Perturbation method

Mean Value

0.0018 0.0018 0.0018

CoV

0.08 0.07 0.07

See Also