Steel trusses

STEEL ROOFSPresentation By- Ar. Roopa Chikkalgi

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Use of trusses in buildings

• Trusses are used in a broad range of buildings, mainly where there is a requirement forvery long spans, such as in airport terminals, aircraft hangers, sports stadium roofs,auditoriums and other leisure buildings.

• Trusses are also used to carry heavy loads and are sometimes used as transfer structures.

• The trusses are widely used to serve two main functions: To carry the roof load To provide horizontal stability.

Robin Hood Airport, DoncasterPresentation By- Ar. Roopa Chikkalgi 2

• There are numerous advantages to using steel trusses instead of traditional wood trusses but the main

reasons are simplicity and strength.

• Some prefer to use the metal roof truss because the building of a structure is all about precision and metalhas a more precise measurement than wood.

• Theses trusses are extremely simple to install.

• You never have to worry about them rotting or deteriorating from the weather.

• You also get more usable space inside your building.

WHY STEEL ROOF?

• Wood trusses are less expensive truss per truss but theyrequire you to install wood headers, the posts have to becloser together and you have more trusses to install.

• You generally have to protect the wood from the weather.

Presentation By- Ar. Roopa Chikkalgi 3

WHY STEEL ROOF?• Prefabricated steel trusses offer a high-strength,

light-weight roof system that can be installedquickly.

• In residential construction, wood trusses stilldominate the industry, where additional strengthis needed, or where greater free spans arerequired Steel roofs are preferred.


Advantages of Metal Roof Truss Structures

1. Even though they are considered to be more expensive, metal roof trusses can span further than wood.

2. Metal roof trusses can be manufactured to exact standards.

3. They are much more lightweight and this allows for larger shipments. This reduces the time it takes to get to the project site.

4. Metal roof trusses are fire resistant.

5. They are compatible with almost all types of roofing systems.

6. No insect infestations can occur.

7. Chemical treatments are not necessary to maintain the trusses.

8. Metal roof trusses are recyclable and therefore environmentally friendly. Presentation By- Ar. Roopa Chikkalgi

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Disadvantages of Metal Roof Truss Structures

1. Skilled labor is required to install metal roof trusses.

2. They are not energy efficient since they allow more heat to escape from the structure.

3. Metal roof trusses allow sound to be more easily transmitted.

4. Temperature fluctuations allow them to move more.

5. When the metal is cut, drilled, scratched or welded, rust can become a problem.

6. The workers have a higher risk of electrocution when installing the metal roof trusses.


Different types of Wooden and Steel Roof Trusses:

• King Post Truss• Queen Post Truss• Howe Truss• Pratt Truss• Fan Truss• North Light Roof Truss• Quadrangular Roof Truss

King Post Truss• King Post Truss is a wooden truss.• It can also be built of combination of wood and

steel.• It can be used for spans upto 8m.


Queen Post Truss

• Queen Post Truss is also a wooden truss.• It can be used for spans upto 10m.

Howe Truss

•It is made of combination of wood and steel. •The vertical members or tension members are made of steel. •It can be used for spans from 6-30m.


Pratt Truss

•Pratt Truss is made of steel. •Vertical members are tension and diagonal members are compression. •These are very economical form of roof trusses. •It can be used for spans from 6-10m.

Fan Truss

•It is made of steel.•In Fan Trusses, top chords are divided into smalllengths in order to provide supports for purlins•It can be used for spans from 10-15m.


INTRODUCTION:NORTH LIGHT TRUSSES ARE TRADITIONALLY USED FOR SHORT SPANS IN INDUSTRIAL WORKSHOP-TYPE BUILDINGS. THEYALLOW MAXIMUM BENEFIT TO BE GAINED FROM NATURAL LIGHTING BY THE USE OF GLAZING ON THE STEEPERPITCH WHICH GENERALLY FACES NORTH OR NORTH-EAST TO REDUCE THE SOLAR GAIN.

NORTHLIGHT ROOF TRUSS

USES –*IT IS USED IN WAREHOUSE, INDUSTRIES, FACTORIES, ETC.*NORTH LIGHT TRUSSES ARE TRADITIONALLY USED FOR SHORT SPANS IN INDUSTRIAL WORKSHOP-TYPE BUILDINGS.*THEY ALLOW MAXIMUM BENEFIT TO BE GAINED FROM NATURAL LIGHTING BY THE USE OF GLAZING ON THESTEEPER PITCH WHICH GENERALLY FACES NORTH OR NORTH-EAST TO REDUCE THE SOLAR GAIN.

Presentation By- Ar. Roopa Chikkalgi

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North Light Roof Truss

•When the floor span exceeds 15m, it is generally more economical to change from a simple truss arrangement to one employing wide span which support trusses at right angles. •In order to light up the space satisfactorily, roof lighting has to replace or supplement, side lighting provision must also be made for ventilation form the roof. •One of the oldest and economical methods of covering large areas is the North Light.•This roof consists of a series of trusses fixed to girders. The short vertical side of the truss is glazed so that when the roof is used in the Northern Hemisphere, the glazed portion faces North for the best light. •It can be used for spans from 20-30m. •Used for industrial buildings, drawing rooms etc.


Quadrangular roof Trusses

Quadrangular Roof Truss (for large spans)

•These trusses are used for large spans such as railway sheds and Auditoriums.


Tubular Steel Truss are used for large span constructions such as factories, industry worksheds, shopping

malls, huge exhibition centre, multiplexes etc. They are generally used for spans as large as 25-30m.

TUBULAR STEEL TRUSS:-

ADVANTAGES OF TUBULAR STEEL ROOF TRUSSES:-

•30% to 40% less surface area than that of an equivalent rolled steel shape. Therefore,

the cost of maintenance, cost of painting or protective coatings reduce considerably.

•The moisture and dirt do not collect on the smooth external surface of the tubes.

Therefore, the possibility of corrosion also reduces.

•The ends of tubes are sealed. As a result of this, the interior surface is not subjected to

corrosion. The interior surface do not need any protective treatment.

•They have more torsional resistance than other section of the equal weight.

Presentation By- Ar. Roopa Chikkalgi13

Typical Steel Connections

Steel ConnectionsMany configurations are used for force transfer in connections. The configuration dependsupon the type of connecting elements, nature and magnitude of the forces (and moments),available equipment, fabrication and erection considerations, cost, etc.

Rivets


Bolts


Gusset plate connections• Gusset plates are usually either made from cold rolled or

galvanized steel based upon their use.• Gusset plates are used for various structures. Gusset plates are

used to connect beams and columns together or to connecttruss members. They can be either the only way of connectingthe beam and columns or they can be used with bolts andwelds.




Galvanized Steel Sheets (Plain and Corrugated)

• Galvanized iron (GI) sheets are steel sheets which are basically coated with zinc and include a range of hot dip galvanized and electro-galvanized steel sheets.

• Corrugated galvanised iron or steel is a building material composed of sheets of hot-dip galvanisedmild steel, cold-rolled to produce a linear corrugated pattern in them.

• The corrugations increase the bending strength of the sheet in the direction perpendicular to the corrugations, but not parallel to them. Normally each sheet is manufactured longer in its strong direction.


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Galvanized Corrugated Steel SheetsPresentation By- Ar. Roopa Chikkalgi

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FIXING ACCESSORIESJ-BoltJ-bolt, also called hook bolt, is a bolt in the form of letter “J” used to fix roof-sheathing or wall sheathing to purlins and other structural members.


INSTALLATION OF CORROGATED SHEETS


Education

Steel trusses