Structural steel
Structural steel is steel construction material, a
profile, formed with a specific
shape and certain standards of chemical composition and strength. Structural steel shape, size, composition, strength, storage, etc, is regulated in most industrialised countries.
|
Steel beam through-penetration. The firestop surrounding the beam is incomplete - packing only, sealant is yet to be applied. The beam itself must be treated with fireproofing to prevent it from twisting and damaging the wall during a fire. The beam is the penetrant. |
All the shapes and sizes are typically listed in steel tables that vary from one country to another.
*
I-beam (I-shaped cross-section)
*WF-Shape (
Wide Flange Steel Materials and Rolling Processes (U.S.))
*H-Shape (another name for WF-Shape. The
flange is equal to, or greater than, the
web)
*Z-Shape (half a flange in opposite directions)
*
Hollow structural section (hollow
square or
rectangular cross-section)
*
Pipe (hollow
round cross-section)
*Angle (L-shaped cross-section)
*Channel (C-shaped cross-section)
*Tee (T-shaped cross-section)
*
Railway rail (asymetrical I-beam)
*Bar, a piece of
metal,
rectangular cross sectioned (flat) and long, but not so wide so as to be called a
sheet.
*Rod, a
round or
square and long piece of
metal or
wood, see also
rebar.
*Plate,
sheet metal thicker than 6 mm or 1/4 in.
As raw material prices fluctuate, often so does building design. During times of lower steel prices, more steel and less
concrete is used, and vice versa. Each set of vendors and users typically maintain national industry associations that advocate the use of its materials versus the other. However, both materials are really needed together. Concrete without steel re-inforcement is not structurally sound. Steel on its own, without solid concrete floors, is likewise not a preferred building method.
As the
critical temperature for
steel is around 540°C (give or take, depending on whose country's test standards one reads at the time), and design basis
fires reach this temperature within a few minutes, structural steel requires external insulation in order to prevent the steel from absorbing enough energy to reach this temperature. First, steel expands, when heated, and once enough energy has been absorbed, it softens and loses its structural integrity. This is easily prevented through the use of
fireproofing. Likewise, although concrete structures on their own are able to achieve fire-resistance ratings, concrete is also subject to severe spalling, especially with elevated moisture inside the concrete at the time it becomes exposed to fire. There is also fireproofing available for concrete but this is typically not used in buildings. Instead, it is used in traffic tunnels and locations where a
hydrocarbon fire is likely to break out. Thus, steel and concrete compete against one another not only on the basis of the price per unit of mass but also on the basis of the pricing for the fireproofing that must be added in order to satisfy the
passive fire protection requirements that are mandated through
building codes. Common fireproofing methods for structural steel include
intumescent,
endothermic and
plaster coatings.
*
Dowel*
Profile (engineering)*
Rebar*
Passive fire protection*
Fireproofing*
Intumescent*
Endothermic*
Drywall
