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Technical Training Basics: What is truss. Goal of this workshop . Share knowledge Actively promote safe working practices Provide product expertise for users. Topics. What is truss Differ ent forces on Truss Analising loading of truss structures Truss standards Questions.
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Goal of this workshop • Share knowledge • Actively promote safe working practices • Provide product expertise for users
Topics • What is truss • Different forces on Truss • Analising loading of truss structures • Truss standards • Questions
What is truss ? • Lattice structure • Made of (mainly) aluminium tubes • Low self weight (easy to handle ) • Modular (easy to transport) • Flexible (lego system)
What is a lattice structure? • A lattice structure is an open triangular structure. • Triangular shapes are stable in hinged connections • Triangulation is essential for strength and stability
The Truss Cross bracing bracing End bracing Main tube Coupling system Node point
Why is Truss made of (mainly) aluminium? Advantages of aluminium • +/- 1/3 of the weight of steel • Non corrosive • Available in large quantities • Easy to machine • Allowable stress for tension and compression is the same
Why is Truss made of (mainly) aluminium? Disadvantages of aluminium • Strength decreases after welding with +/- 50% • Less stiff as steel • More difficult to weld • More expensive
Main advantage of a Truss structure : Low self weight in relation to a high load bearing capacity. Achieved by.. Bringing the material to the position where you need it !!!!!
Different type’s of coupling systems • Tube coupler • Gusset / Endplate • Hinge connection Male / Female • Conical coupler
1: Tube connection-Very high bearing stress in the main chord-Open space between main chord.
2: Gusset / Endplate-Bending force in gusset Plate-Open space between main chord
3: Hinge connection Male / Female-Fixed Male/Female sides wear given extra deflexion
Mounting different brands of truss together. • Although the truss looks the same each type of truss has different technical specifications • Calculation of the system with different specifications. • Responsibility
Different forces on Truss • Loading Forces • Internal reaction Forces
Different type’s of loading • Point load • Multiple point load • Concentrated load • Uniformly distributed load • Cantilever load • Normal force
Internal reaction forces in the Truss • Bending moment • Transversal forces ( also known as shear force ) • Normal forces • Torsion force • The reaction of these forces is • Deflection
This figure indicates where the internal forces are active in the truss. Normal force Shear force Normal force Bending moment Normal force
Bending moment To strain under tension, causing a straight line structure to turn into a curve-shape
Examples of situations when a bending moment occurs: • Self weight caused by the Force of gravity • Live loading such as lightning fixture or Sound equipment • Curtains, back drapes • Wind force.