Pre-Engineered Buildings (PEB) were conceptualised and introduced into the Steel Building industry to implement fast design, fabrication, delivery & erection of low rise structures which are easy to handle and very cost effective. They feature a structural steel framework concept of primary framing systems/members, secondary framing systems/members, duly covered with roofing & cladding sheeting connected to each other.
PRIMARY FRAMING SYSTEM
Primary framing consists of columns and rafters with tapered web and variable flanges. These are manufactured by welding together cut plates to form the desired frame Isections. The tapered sections are welded at factory / bolted at site at splices to form the desired frame profile. These frames in PEB are normally moment resisting frames with fixed or pinned bases as mandated by the design.
SECONDARY FRAMING SYSTEM
Secondary framing consists of elements which support the roof and wall sheeting and transfer load to the primary framing. These include roof purlins, wall girts, eave struts, clips, etc. which has minimum yield strength of 345 Mpa.
Purlins and girts shall be cold formed Z sections, 120-300 mm deep with 50-100 mm flanges with a thickness of 1.52 – 2.5 mm, these are fixed to the top flanges of the rafters by means of clips welded to the rafters, and the purlin web bolted to the clips. Purlin ends overlap to act as continuous beams.
Wall girts are cold formed Z sections, with depth of 150-250 mm and having thickness 1.5-2.5 mm which are fixed to the outer flange of the side wall columns by means of clips welded to the column and girt web bolted to the clips.
- Industrial Buildings
- Aircraft Hangers
- Cold Stores
- Commercial Buildings
- Office Building
- Railway Stations / Platforms
|S.No.||Particulars||Color Coated Galvanized/ Galvalume Sheet||Chemical Resistance FRP Sheet|
|1.||CORROSION/WEATHER RESISTANCE||Color Coated Galvanized / Galvalume Sheets have weaker corrosion resistance, when used for Roofing/Cladding in Industrial where the environment is Acidic / Alkaline, Salt Water, because the base metal is mild steel with 120-150 micron coating of Zinc/Alu-Zinc.||Whereas FRP Sheets are used for Factories or Industries
which has corrosive/acidic environment, have special
corrosion/weather resistance gelcoat coating (400-500
microns), made in Isopthalic, Vinyl Ester, Bisphenol and
other various types of unsaturated Polyester Resin are
excellent in resistant to extremely corrosive
It can handle direct exposure to acids, salt water, oil and many other common corrosives.
|2.||Lifespan||Due to corrosion/weathering effects on Color Coated Metal Sheet, their life span is 3-5 years only.||Fiberglass Sheets does not have corrosion/weathering effect and therefore has a much longer duty life than steel. Approximately 10-15 Years.|
|3.||Long Lasting Aesthetics||Color Coated Sheets can stand only for the period of 5 years and after this period due to corrosion/weathering effect, it looks faded.||FRP Sheets have long lasting aesthetics and it stands like new sheets for a period of minimum 10 Year because of in built color and U/V resistance properties.|
|4.||Creates Thermal Comfort||Since the base material is mild steel and it gets expansion and contractions easily in summer and winters.||Since FRP is a reinforced plastic, it has very low expansion and contraction in summer & winters. Also, it is a good insulator with low thermal conductivity.|
|5.||Insulation Properties||Being the metal sheets, they got heat up very quickly in summers and transmit heat into the sheds which creates discomfort to the working environment.||FRP does not conduct heat. FRP Sheets maintain a constant temperature and are always cool to touch. It is a reinforced plastic product, in which one of the major raw material is glass fiber which is used in making insulation slabs so it has a better insulation properties than metal sheets.|
|6.||Strength & Stiffness||It is common myth that steel has more strength and stiffness than FRP but due to weathering effects all its strength & stiffness become weak in due course of time.||Fiberglass Sheets are reinforced plastic product which has equal or better in strength/stiffness than steel. Also because of its high mechanical properties, it does not loose strength due to weathering effects.|
|7.||Modulus of Elasticity||Modulus of elasticity : 29 x 106 psi||Will not permanently deform under working load. Module of elasticity : 2.8 x 106 psi|
|8.||Maintenance Free||Since Metal Sheets easily got corrosion & weathering effects, they need to be maintained regularly and have a maintenance cost||FRP Sheets does not have weathering/corrosion effect so they are maintenance free.|
|9.||Electrical Conductivity||Metal likes steel and aluminium conduct electricity and must be grounded.C||Whereas FRP Sheets are non-conductive and has high dielectric capability.|
|10.||Cost||Lower initial material cost but more expensive to maintain and much higher cost to life ratio.||FRP Sheet initial material cost is expensive than steel but due to less maintenance and longer product life allow for a lower lifecycle cost. Corrosion is an area where FRP cost can also be justified, as it’s the greatest advantage over steel.|
|11.||Weight||Metal Sheets are much heavier than FRP. It required heavy steel structure which ultimately increases the cost.||FRP Sheets weight is 75% less than steel. So it does not require that heavy steel structure and overall project cost can be reduced. This also makes the material much easier to lift for installation or repairs, leading to lower maintenance.|
|1.||Density||40 ± 2 Kgs m3|
|2.||Compressive Strength at 10% deformation||2.1 Kgs/cm3|
|3.||Tensile Strength||4.0 Kgs/cm2|
|4.||Bending Strength||4.2 Kgs/cm3|
|5.||Adhesion Strength (Foam to Steel)||3.0 Kgs/cm2|
Dimensional Stability (48 hours)
|7.||Closed Cell Content||90-95%|
|8.||Temperature Range||-180°C to +140°C|
Temperature Conductivity at 0°C
(design value 0.020 k Cal/m-hr/°C or 0.023 w / m k
|10.||Water Absorption||0.2% volume at 100% RH|
|11.||Vapour Permeability (At 90% RH & 38°C)||0.8/0.12 GMS/HR m2 as per
|12.||Fire property extent to burn as per BS 4735||Max. 100 mm|