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Steel
Structures
The Disadvantages of Steel Structures
Steel structures need to be
adequately protected by the application of an appropriate barrier between the
metal element and the atmosphere - surface preparations ensure the protection
and prolong the serviceable life of a steel structure.
By Natasha Gilani
Steel is one of the most
abundantly used structural materials, owing to its strength, scrap value and
ease of transport.
It is used for pipes (water,
compressed air and gas distribution), utility lines, fuel distribution
structures, sewage systems, pontoon structures, and a host of accessories such
as chocks, cleats, bollards, hangers, expansion joints and anchors.
Steel structures are
susceptible to various environmental and other risks which severely compromise
their structural integrity, safety and longevity.
Corrosion
Steel is susceptible to
corrosion in outdoor atmospheres.
Corrosion is the destruction
of a metal due to its reaction with atmospheric oxygen. This electrochemical
oxidation produces metal oxide, or rust.
Surface preparations ensure
the protection and prolong the serviceable life of a steel structure.
Some common types of steel
surface preparation methods include dry abrasive blasting, water blasting, coal
tar coatings, paint and substituting steel with corrosion-resistant alloys,
such as titanium alloys, nickel alloys, aluminum alloys and stainless steel.
These, and other
corrosion-protecting methods are typically expensive and are restricted by
practical limitations such as accessibility, location and time.
Fireproof Treatment
Steel structural elements
require expensive fireproof treatment.
Although steel elements,
such as stand-alone structures, are incombustible, their strength reduces at
high temperatures due to fire or when other materials within a building burn,
making them susceptible to buckling.
Furthermore, steel, being an
excellent conductor of heat, ignites materials in contact and causes fires
which rapidly spread to other sections of a building.
Steel structures may require
additional fireproofing, and buildings may need to be installed with
appropriate sprinkler systems, as defined by building-code requirements of a
particular locality.
Fireproof coatings, such as
expanded mineral coatings, concrete and intumescent materials, ensure that the
temperature of steel does not exceed to ignition limits in the event of fire.
Oftentimes, steel structures
are enclosed in gypsum block, masonry block, gypsum board and clay tile
enclosures that protect them from heat.
These enclosures are
typically expensive and require additional maintenance.
Fatigue and Fracture
Large variations in tensile
strength expose steel elements to excessive tension, which reduces its overall
strength.
Steel is also susceptible to
brittle fracture when it loses its ductility. This increases its chances of
buckling, which is typically counterbalanced by adding expensive steel columns
that stiffen the primary structure.
Natasha
Gilani has been a writer since 2004,
with work appearing in various online publications. She is also a member of the
Canadian Writers Association. Gilani holds a Master of Business Administration
in finance and an honors Bachelor of Science in information technology from the
University of Peshawar, Pakistan.
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