OPTIMIZATION AND RATIONALIZATION OF TRUSS DESIGN

In design of steel trusses different types of geometries (A-type truss, Fink truss, Pratt truss, Howe truss, King post truss, Queen post truss etc) and sections (Angle section, Tube section, Square hollow section etc) are widely used. In present work, roof truss of span 16m has been analyzed for different geometries and sections to get the desired optimum truss design. The design is further optimized for varying slopes of truss. The support conditions (fixed/hinged) and type of connection (welded/bolted) between truss members also effect the forces in truss members. Although in the truss design, it is assumed that purlins are supported on truss joints, but due to specification of roof sheet, there may be a limitation of maximum purlin spacing which may cause the purlins resting on truss members instead of joints. The various truss analyses are performed by using structural analysis software i.e. STAAD Pro. The analysis results are compared to obtain optimum and accurate truss design. The results indicate that A-type truss has lesser weight compared to other truss geometries. The truss consists of tube/square hollow section is having much lesser weight compared to angle section. The optimum truss slope is found nearly 24⁰. The truss with rigid connection between members is found heavier than the truss with pin connection. Similarly truss supported on fixed base/purlins resting on truss members causes bending moment in top chord of the truss members which in turn modify the sectional requirement of the members. Hence case specific analysis is necessary for rational solution of truss design.