Behaviour of Long-Span Steel Truss Systems with Different Geometrical Configurations under Lateral Loads Using STAAD.Pro

Long span steel roof structures are widely used for industrial shed, warehouse, hangar, exhibition hall and other buildings which require that the space between columns is unobstructed. Of all the structures forms available, the triangulated truss is the most material efficient method of spanning large distances as the members are idealised to work under axial tension or compression. The internal geometry of a truss roof is, however, very critical to its lateral-load performance, as is the cross sectional shape of the members. With the three most popular long span roof truss designs, namely, the Fink (Flink), Howe and the King Post, and three typical steel sections provided as specified in Indian Standards, namely, Indian Standard Medium Weight Beams, rolled steel channel and rolled steel angle, there are a total of nine structural categories under examination in this paper. A typical eave height of 3.5 m for the representative industrial building of 35 m × 25 m plan was modelled and analysed in the STAAD software.Pro for combined dead, live and lateral wind loading as per IS 875 (Part 3):2015 for basic wind speed of 39 m/s. 15 independent and combined load cases were analyzed and the shear force, axial force, support reaction and nodal deflection were then extracted and compared systematically for each configuration. The results demonstrate that the Howe truss configuration always has the lowest peak shear force, axial force, support reaction, and deflection as compared with the other two types of trusses (Fink and King Post); and that the ISMB (beam) section has the lowest peak force in all the variables as compared to the other two sections (channel and angle). A comparison of the costs based on quantity further suggests that the Howe truss built of ISMB sections is the most economic of the nine configurations studied, and is therefore recommended as the best configuration for long span industrial roofs of the size investigated.