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ADVANTAGES
AND SAVINGS FROM COLD FORMED SHS / RHS SECTIONS :
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Sectional
properties
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These
sections have the highest possible resistance to torsion, as
the entire enclosed area of the section is effective.
Their low flat - width ratio (w/t) permits higher design stresses.
Comparably higher moment of inertia about minor axis prevents
premature elastic buckling.
Due to availability of flat surface, joining by bolting or welding
is simplified.
Due to high moment of inertia deflections are lower.
Consistency in quality.
Smooth contact and low drag coefficient minimizes wind load
on exposed surface.
Availability in exact length reduces wastage of steel.
High strength to mass ratio.
Better fire resistance due to larger heat dissipating area and
lower heat absorbing area.
Attractive shapes and clean lines add to their architectural
beauty.
Sealed end prevents internal corrosion.
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Savings
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Ease of
erection and adaptability for prefabricated panels reduces
construction time.
Due to light weight, cost of other supporting members, foundations,
handling and transportation is reduced.
Smaller exposed surface area reduces cost of painting and
susceptibility to corrosion.
Direct welding to each other avoids the need for gusset plates
which saves 2-3% cost in steel and sledding electrodes.
ABOVE FACTORS EFFECT SAVINGS, IN DIRECT AND INDIRECT COST,
TO THE TUNE OF 30% TO 40% COMPARED TO OTHER SECTIONS.
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MANUFACTURING AND QUALITY CONTROL :
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Cold
formed sections are manufactured on a continuous mill from steel
sheets strictly conforming to IS 1079 OR IS 10748 specifications
with guaranteed weld ability. These sections are formed from
a circular mother tube which is continuously welded. Thus uniformity
of properties is assured throughout the length and through out
the manufactured batches.
THE SHS RHS are tested for tensile properties and inspected
for dimensional accuracy according to IS 4923 or ASTM A500 specifications.
Unless otherwise specified tubes are cut to a length of 6±.05
meter and given a light oil coating as a temporary protection
from rusting.
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APPLICATIONS
OF SHS / RHS :
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Cold
formed light gauge box sections manufactured finds wide field
of structural applications in the construction industry. These
sections can be used :
in construction of heavy duty industrial structures in the form
of purlins, trusses, gable and runners, for factory sheds with/without
crane gantries etc.
in construction of light duty structures such as bus-stands,
milk booths, temporary pavilions, construction sheds, godowns,
cycle stands, railway platform sheds, poultry sheds, tents for
defence personnel or migratory labour, market sheds etc.
in construction of small span pedestrian bridges as supporting
structural members, railings for minor and major bridges for
crossing over roads, railway lines, canals, rivers etc.
as wall stud faced on both sides by a variety of wall material
such as plywood, fibre board, gypsum boared etc.
as centering material such as props, runners, stiffening members,
scaffoldings, spans supporting the shuttering plates etc.
as structural members supporting false ceiling, hand rails for
stairs, gates for farms, factories, railway level crossing etc.
as framing members for doors, windows, escalators, etc.
as structural members for T.V. towers, electrical towers, lighting
or electrification poles, highway guard rails, portal frames
for highway signs and hoardings where resistance to wind is
an important factor.
Space frames for petrol pumps, restaurants, sports stadia, halls
for social functions, auditoria, exhibition pavilions etc.
to replace wooden members in bullock carts and to increase their
carrying capacity.
tractor trolleys and agricultural implements.
DESIGN AIDS :
The various tables and figures given in the appendix show the
structural properties of the various sections and data suitable
for designing structural members with different types of loads
and some details for joining the SHS / RHS to each other or to
any other conventional hot rolled sections.
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APPENDIX
I
DESIGN AIDS
CONTENTS
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Sectional
properties of SHS / RHS |
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Comparison
of Hot Rolled ISMB with SHS / RHS |
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Tables
for allowable load on SHS / RHS beams. |
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