Forces in Bracing Elements of Timber Trusses

Abstract

This research analyzes the forces in bracing members of timber trusses through numerical modeling using the computational system Strap, considering the three-dimensional structure behavior. The values obtained are compared to values set by the Brazilian standard ABNT NBR 7190 (1997), which considers the side instability of the bracing elements. The results were also compared with the values proposed by the methods of the European standard EUROCODE 5, the South African Standard SABS 0163 (1994) and with the work developed by Underwood (2000). The computer models represent industrial sheds with 12 to 24 meters spam, 24 to 96 meters long with heights of pillars 3, 4 and 6 meters. The structural models analyzed were the Pratt and Howe truss types, considering wood provide from C30 and C40 strength classes. The results show that the forces acting on the bracing of the three-dimensional models are higher than the values obtained by the method of ABNT NBR 7190 (1997), and the values obtained by the methods proposed by EUROCODE 5 and Underwood (2000) are more reliable in the overall behavior of the structure.