| Hot-rolled cut-T-section chords were adopted in the national standard of architecture drawing "Light weight triangular steel roof truss(cut-T-section)" 06SG517-2,together with angle-section web members.This type of truss has a simple outline and a small number of web members.The web plate of Cut-T-section chord may be used as gusset plate,so the truss has good economy and is easy to fabricate.The secondary stress appeared inevitably because of rigid connection of the node.Whether the effect of secondary stress is considered or not,and how much it affects the ultimate bearing capacity of truss,which still need further study.In this paper,secondary stress of 22 A-truss in the drawing 06SG517-2 was analyzed by software ANSYS.The results showed that the maximum secondary stress of upper chord located in the panel adjacent to roof ridge with the value exceeding primary stress,and the secondary stress in end panel is relatively smaller with the value of one third of the primary stress.As the end panel of chord controlled the design of upper chord due to the largest axial force in this panel and the same section of all panels, so the effect of secondary stress was not remarkable.For lower chord,the maximum secondary stress was less than 20 percent of the primary stress and the effect is small, therefore it can be neglected in design.The secondary stress of web member was not considered despite it is relatively large because the Code considered strength reduction when single-angle section adopted with one leg connection.In order to evaluate the safety of trusses and to obtain distribution change and effect of secondary stress after plastic deformation occurred in members,the paper also analyzed the ultimate bearing capacity of all trusses in the drawing.The analysis results revealed that all trusses were safe and reliable.Meanwhile,the failure mode of trusses and the regulation plastic redistribution of secondary moment were obtained,which may be referred in practice...
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