The paper presents preprocessing steps and the finite element analysis of a complex steel assembly. Static and vibration analysis is performed on a three dimensional frame model, built on the basis of data transferred from Computer Aided Design (CAD) application to a Finite Element Analysis (FEA) preprocessor. CAD features transfer via DXF format is checked for precision for further more complex entities definition in FEA preprocessor. FEA results within the transfer precision settings are underlined.