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Chapter:
1. Define Steel Structures.
Steel Structures are the structures made up of steel components connected together to sustain and share the applied loads with adequate safety and serviceability and are considered as the better alternatives in comparison to other structures like concrete and timber structure for the place where the structure is supposed to function for greater magnitudes of loads and other engineering materials are scarce.
The advantages of Steel over other materials for construction are:
- It has high strength per unit mass. Hence even for large structures, the size of steel structural elements is small, saving space in construction and improving aesthetic view.
- It has assured quality and high durability.
- Since standard sections of steel are available which can be fabricated in site, there is a lot of saving in construction time.
- Steel structures can be strengthened at any later time, if necessary. It needs just welding additional sections.
- By using bolted connections, steel structures can be easily dismantled and transported to other sites quickly.
- Material is reusable.
Some of the disadvantages of Steel Structures are:
- It is susceptible to corrosion.
- Maintenance cost is high.
- Steel members are costly.
Structural Steel is steel construction material formed with specific shape or cross section and certain standards of chemical composition and mechanical properties. Depending on the manufacturing process, Steel Sections are classified as:
- Hot Rolled Section
- Cold rolled or Cold-formed section
Hot-Rolled Section:
Hot-rolled Section are classified by the Bureau of Indian Standards as follows:
- Beams /Rolled Steel I section (ISJB, ISLB, ISMB, ISWB)
- Columns / Heavy weight Beams (ISCS, ISHB)
- Parallel Flange Beams and Column Sections (ISNB, ISWPB)
- Channels (ISJC, ISLC, ISMC, ISMCP)
- Angels (ISA)
- T-Sections (ISNT, ISDT, ISLT, ISMT, ISHT)
- Tubular Sections
- Rectangular / Square Hollow sections
Rolled-steel I section (Beams):
- Indian Standard Junior beams - ISJB
- Indian standard Light Beams - ISLB
- Indian Standard Medium Beams - ISMB
- Indian Standard Wide- flange Beams - ISWB
- Indian Standard Heavy Beams - ISHB
Columns / Heavy weight beams:
- Indian Standard Column section - ISCS
- Indian Standard Heavy Weight beam - ISHB
Rolled Steel Channel Section:
- Indian Standard Junior channel - ISJC
- Indian Standard Light Channel - ISLC
- Indian Standard Medium weight Section - ISMC
- Indian Standard Special Channel - ISSC
As per IS : 808-1989, following channel sections have also been additionally adopted as Indian Standard Channel Sections;
- Indian Standard Light Channels with parallel flanges - ISLC (P)
- Medium weight channels -MC
- Medium weight channels with parallel flanges - MCP
- Indian Standard Gate Channels - IS
Rolled Steel Angle Section:
- Indian Standard equal angle - ISA
- Indian Standard unequal angle - ISA
Rolled steel Tee Section:
- Indian Standard Normal Tee bars - ISNT
- Indian Standard Heavy flanged Tee bars -ISHT
- Indian Standard Special legged Tee bars - ISSLT
- Indian Standard Light Tee bars - ISLT
- Indian Standard Junior Tee bars - ISJT
Rolled Steel Bars:
- Indian Standard Round bars - ISRO
- Indian Standard Square bars - ISSQ
Cold-Formed Light-gauge Sections
Cold-formed light-gauge sections are used where thicker hot-rolled sections become uneconomical especially in small buildings subjected to lighter loads and are produced from steel strips with maximum thickness 8 mm.
