Abstract

In the analysis of bracing systems imperfections of the restrained elements should be considered. According to EC3 this effect can be calculated by means of the equivalent stabilizing force, which replaces (in simplified way) initial bow imperfection of the braced element. However, alternative suggestions of the equivalent stabilizing force calculations can be also found in the literature. In this paper segment of the pitched roof with truss girders, purlins and trapezoidal sheeting was analyzed in two variants: with bar bracing and with trapezoidal cladding as a part of the bracing system (resisting in-plane forces). The influence of the imperfections of the truss girder on the axial forces in the purlins in two cases of the bracing systems were observed. Geometrically nonlinear analysis using shell elements was performed in Abaqus. Initial imperfections of the truss girder were implemented in direct way (by importing imperfect geometry using LBA) and compare to the analytical result according to three selected methods. A few aspects that are omitted in analytical procedures were included in numerical analysis, e.g. the eccentricity between structural elements and the stiffness of selected connections. Results showed discrepancies between numerical and analytical outcomes.

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