rahul_long span structures

8/4/2019 Rahul_Long Span Structures

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Long Span Structures

How long is long-span for buildings?

Spans of above 20m are usually difficult to achieve by

ordinary RC structure

Technical considerations of the size of the spansignificantly affect the aesthetic treatment of the building.


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History of long span structures?

Pre-industrial age the widest spans were achieved bymasonry vaults or domes.

Development ofreinforced concrete (19th century) Resist tension as well as compression

RCC reduced the section thicknesses than those inmasonry

Development ofFerro-cement eliminated much of the

temporary formwork. Final dome/vault was a composite structure

Compressive form-active structures are also produced inmetal


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Applications/Need for long span structures:

Large amount of people gathering areas

Arena/Stadium Churches

Unobstructed spaces

Factories Theaters

Airports

Large artifact museums



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Materials for various forms of long span structures

Reinforced concrete (in-situ, precast)

Metals (different forms of steel, aluminum and their alloys)

Timber and laminated timbers Composite - Metal/RC

Fabric materials

Fiber reinforced plastics


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Forms of long span structures:

Arched structures

Dome structures

Cable structures Truss structures

Flat slabs

Folded slabs

Shell structures Pneumatic structures



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One way to categorize long-span structures:

Form active systems

Vector active systems

Section active systems

Surface active systems


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Form active systems

Flexible, non-rigid, forces

are effected by particular

form

Arch structures

Cable structures

Pneumatic structures



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Vector active systems

Short, solid, straight lineal

members, forces are effected

through multidirectional

forces to tension orcompressive elements

Flat trusses

Curved trusses

Space frames



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Section active systems

Rigid, solid, linear elements,

forces are effected by

mobilization of sectional

forces

Beam structures

Frame structures

Slab structures



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Surface active systems

Flexible/ rigid planes, forces

are effected by mobilization of

sectional forces

Plate structures

Folded structures

Shell structures



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hy Steel Roofing?

Excellent as a tensile structural member

Good resistance against earthquakes and hurricanes

Fire resistant and non-combustible

Resistant to decay and heavy winds

Provides better indoor air quality (than most materials)

With proper treatment, resistant to moisture, rusting & corrosion.

Durable and offers increased design flexibility

Compatibility with other construction materials


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Beam Types


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North Light Trusses


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Lattice Girders and Gutters


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Height : 6m

c/c distance of angle purlins: 1.8m

Slope of the roof : 15 degree

GI sheet roofing

Conventional tube lights used for

artificial lighting, hanged from the

lattice girders.

Joinery of sheeting and purlins with J

- hook


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Fiber glass sheeting used at

intervals in addition to north

light for lighting the

interiors.

GI sheet roofing

Double lattice girders



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DETAILS OF

BRACED COLUMNS

Bracket supporting the

aluminium gutter

Rain water

down take pipe

45 degree bracingsystem used for the

stanchion.

Joints welded.



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Components of a Crane System & GantryGirders

Column or stanchion

Brackets

Gantry/crane girder

Crane runway (rail)

Crane bridge

Trolley/cab


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Components of a Crane System & Gantry Girders


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Components of a Crane System & Gantry Girders

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