Finite Element Analysis of the Effect of Screw Number on the Connection Behaviour for Cold Form Steel Truss Systems

Abstract

The demand for cold formed steel (CFS) has increased due to its advantages such as lightweight with high strength to weight ratio, easy for transportation, can be manufactured in different configurations and shapes and etc. CFS trusses were frequently used in roof structures in industrial and residential buildings. The function of a truss was to transfer load from point of application to the supports as directly as possible. In this research, the screw connections at the side and peak location of Fink and Howe truss were being modelled using LUSAS. Lipped channel (LCS) and rectangular hollow section (RHS) were selected as material of cold formed steel truss. The aim of this analysis was to investigate the behavior of connection in cold formed steel truss system based on different number of screws. Then the validation was carried out for the finite element analysis results with design checking procedure in Eurocode 3. By modifying the number of screws through finite element analysis, the connection strength based on the results such as displacement, stress, shear and moment were discussed. The outcomes of modelling results show that both types of cross sections gave different performances. The displacement in LCS decreased when more number of screws were added to the connection. Instead, for RHS the displacement increased slightly when the number of screws increased. The principal stress in both cross sections declined when more screws were inserted. Similarly, shear force for both cross sections dropped when there were more screws except for the peak location of Fink truss in LCS where it shows the lowest shear force when one or two more screws were added to the connection. Meanwhile, moment decreased when more number of screws were added. The only increment of moment happened at the peak location of Fink truss in the RHS. It shows that the typical number of screws are sufficient for the connection of Fink truss and Howe truss.