Application of TrussesName M.UmarRoll number BSME01113128Sec 0Department Mech. EnggInstructor M Adeel Butt
What is Truss?In architecture and structural engineering a truss is a structurecomprising one or more triangular units constructed withstraight members whose ends are connected at joints referredto as nodes External forces and reactions to those forces areconsidered to act only at the nodes and result in forces in themembers which are either tensile or compressive forces.
Types of truss?There are two basic types of truss. 1.The pitched Truss 2.The parallel chord Trussa)The pitched truss, or common truss, is characterized by itstriangular shape. It is most often used for roof construction.Some common trusses are named according to their webconfiguration. The chord size and web configuration aredetermined by span, load and spacing.b) The parallel chord truss, or flat truss, gets its name from its parallel top and bottom chords. It is often used for floor construction.A combination of the two is a truncated truss, used in roofconstruction. A metal plate-connected wood truss is a roof orfloor truss whose wood members are connected with metalconnector plates.
Types: Pratt Truss Bowstring Truss King Post Truss Lenticuler Truss
Explanations:AThe Pratt truss was patented in 1844 by two Boston railwayengineer, Caleb Pratt and his son Thomas Willis Pratt .Thedesign uses vertical members for compression and horizontalmembers to respond to tension .What is remarkable about thisstyle is that it remained popular even as wood gave way to iron,and even still as iron gave way to steel. The continuedpopularity of the Pratt truss is probably due to the fact that theconfiguration of the members means that longer diagonalmembers are only in tension for gravity load effects. This allowsthese members to be used more efficiently, as slendernesseffects related to buckling under compression loads (which arecompounded by the length of the member) will typically notcontrol the design. Therefore, for given planar truss with a fixeddepth, the Pratt configuration is usually the most efficientunder static, vertical loading.BNamed for their shape, bowstring trusses were first used forarched truss bridges known as tied-arch bridgesThousands of bowstring trusses were used during World War IIfor holding up the curved roofs of aircraft hangars and othermilitary buildings. Many variations exist in the arrangements ofthe members connecting the nodes of the upper arc with those ofthe lower, straight sequence of members, from nearly isoscelestriangles to a variant of the Platt truss
COne of the simplest truss styles to implement, the king postconsists of two angled supports leaning into a common verticalsupportThe queen post truss, sometimes queen post or queen’s post issimilar to a king post truss in that the outer supports are angledtowards the center of the structure. The primary difference isthe horizontal extension at the centre which relies on beamaction to provide mechanical stability. This truss style is onlysuitable for relatively short spansDA Lenticuler pony truss bridge is a bridge design that involves aLenticuler truss extending above and below the roadbed.Applications:Component connections are critical to the structural integrity ofa framing system. In buildings with large, clear span woodtrusses, the most critical connections are those between the trussand its supports. In addition to gravity-induced forces (a.k.a.bearing loads), these connections must resist shear forces actingperpendicular to the plane of the truss and uplift forces due towind. Depending upon overall building design, the connectionsmay also be required to transfer bending moment.
Wood posts enable the fabrication of strong, direct, yetinexpensive connections between large trusses and walls. Exactdetails for post-to-truss connections vary from designer todesigner, and may be influenced by post type. Solid-sawn timberand gleam posts are generally notched to form a truss bearingsurface. The truss is rested on the notches and bolted into place.A special plate/bracket may be added to increase connectionload transfer capabilities. With mechanically-laminated posts,the truss may rest on a shortened outer-ply or on a shortenedinner-ply. The later scenario places the bolts in double shear andis a very effective connection