SUB : STRUCTURE
TOPIC : TRUSSES AND STEEL
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 into
three 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.
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 truss
Truss 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 trusses
A 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 truss
A 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 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
• It differs from cast iron and wrought iron in its car bon content.