SUB : STRUCTURE

TOPIC : TRUSSES AND STEEL SECTION

AAERT SID SEM : 1

WHAT IS TRUSSES ?A framework , typically consisting of rafters , posts,and struts , supporting a roof , bridge or other structure .

A truss is a structure comprising five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes. External forces and reactions to those forces are considered to act only at the nodes and result in forces in the members which are either tensile orcompressive forces. Moments are explicitly excluded because, and only because, all the joints in a truss are treated as revolutes.A planar truss is one where all the members and nodes lie within a two dimensional plane, while a space truss has members and nodes extending intothree dimensions. The top beams in a truss are called top chords and are generally in compression, the bottom beams are called bottom chords and are generally in tension, the interior beams are called webs, and the areas inside the webs are called panels.

TRUSS

o Vierendeel truss

o Town's lattice truss

o Pratt truss

DIFFERNT TYPES OF TRUSS

o Lenticular truss

o King post truss

o Bowstring truss

• Etymology of trussTruss is derived from the old French word trouser, around c.1200, which means "collection of things bound together." The term truss has often been used to describe any assembly of members such as a Cruck frame or couple of rafters but often means the engineering sense of "A truss is a single plane framework of individual structural member connected at their ends of forms a series of triangle to span a large distance."

• Characteristics of trussesA truss consists of straight members connected at joints, traditionally termed panel points. Trusses are composed of triangles because of the structural stability of that shape and design. A triangle is the simplest geometric figure that will not change shape when the lengths of the sides are fixed. In comparison, both the angles and the lengths of a four-sided figure must be fixed for it to retain its shape. The joint at which a truss is designed to be supported is commonly referred to as the Munster Point.

• Space frame trussA space frame truss is a three-dimensional framework of members pinned at their ends. A tetrahedron shape is the simplest space truss, consisting of six members which meet at four joints. Large planar structures may be composed from tetrahedrons with common edges and they are also employed in the base structures of large free-standing power line pylons

STEEL SECTION

WHAT IS A STEEL SECTION

• Steel section is construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and mechanical properties.

• Steel used in engineering structure, usually manufactured by either the open – hearth or electric furnace process.

• Man made metal derived from iron – which is its major constituent.

• It differs from cast iron and wrought iron in its car bon content.

STEEL - SECTIONS

STEEL - SECTIONS

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