Building Construction 3

Submitted by:FAIRUZBARC/8008/10

ARCHES AND DOMES1. Arches and its form 2. Arches and its construction technique

3. Domes and its form 4. Domes and its construction technique

Arches:

Is a structure that spans a space and supports a load.

Provides a structure which eliminates tensile stresses in spanning a great amount of open space. 

All the forces are resolved into compressive stresses.

Building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torsional stress is applied to them.

Arches consists of different components.

Element Of Arches:

1. Keystone

2. Voussoir

3. Extrados

4.  Impost

5.  Intrados

6.  Rise

7.  Clear span

8.  Abutment

Arches:

Arches And Its Construction Technique :

Construction Of An Arch:

An arch requires all of its elements to hold it together.

Firstly build a frame which exactly follows the form of the underside of the arch. This is known as a centre or centring.

The voussoirs are laid on it until the arch is complete and self-supporting. For an arch higher than head height, scaffolding should be used by the

builders.So that the scaffolding can be combined with the arch support. Arches would fall down when the frame was removed if construction or planning had been incorrect. The interior and lower line or curve of an arch is known as the intrados.Old arches sometimes need reinforcement due to decay of the keystones, forming what is known as bald arch.

Flat Arch ( Jack/Straight Arch)•Appears to be the most easiest.•Construction is tricky•Require skill to make them look good•Provides support at openings •efficiently uses the compressive strength of the masonry

Corbelled Arch (False Arch)•Easiest to construct & Not a true arch•Not entirely self supporting structure•Constructed by offsetting successive courses of stone •Require significantly thickened walls and an abutment of other stone or fill to counteract the effects of gravity.

Triangular Arch (Miter Arch)•Simple single piece stone laid together. •The span is limited by the size of the available material. •Formed by two large diagonal stones that mutually support each other to span an opening.

Different Types Of Arches:

Semicircular Arch•First created before the Roman times.•Known as the Roman Arch after the people that brought it to perfection•A round arch drawn from a single center.

Bullseye Arch (Circular arch)•Used for windows•A double arch with two or four keystones.•Made of two semicircular identical arches. •The top portion of the circular arches is called The Upper Arch and the lower portion is called The Invert .

Bell Arch•A Roman arch sat on corbels that are imposts.•Often carved from one piece of stone.•Rests on two rounded corbels resulting in a shape somewhat similar to a bell.

Islamic Arch•Also known the Moorish Arch, •Defines the feature of Moorish architecture.

Segmental Arch•Based on a segment of a circle.•Curve is a less than semicircular segment of a circle.

Foil Arch•Embellishments of Gothic architecture. •Also known as Trefoil Arch.

Different Types Of Arches:

Pointed Islamic Arch•A pointed variation of the Moorish arch.

Gothic Arch•The defining feature of the late middle ages in Europe•Is a sharp-pointed arch.•Formed of two arc segments (parts of a circle). 

Arch based on circular arcs•There are many varieties of these.• This one is known as the three centre arch.

Geometrical Arch•Based on geometrical or mathematical curves. •Also known an elliptical arch.

Venetian Arch• A variation of the bell arch.

Different Types Of Arches:

Ogee Arch•Based on opposing circular arcs.•Pointed arch.•Each side consists of two contrasting curves.

Skewed Arch•An arch that is not at right angle to the wall it traverses. •Most famously first used in early railway viaducts.

Domes:

Is a type of shell structure Are hemispherical in shape. Used as roof structure. Transmits load more than 2 directions to

support Transmits load without bending or

twisting. Constructed of stone , concrete & brick. Supported on circular / regular polygon

shaped walls. Have certain height & diameter ratio. Have very small thickness. Can b constructed with or without lanterns.

Onion domeAlso known as bulbous domeIs a bulbous shape tapering smoothly to a point, strongly resembling an onion, larger in diameter than the drumIts height usually exceeds its width. 

Geodesic Dome •  Geodesic domes are

the upper portion of geodesic spheres.

• They are composed of a framework of triangles in a polyhedron pattern.

Different Types Of Domes:Corbel dome• Different from a 'true

dome'• Consists of purely

horizontal layers• As the layers get higher,

each is slightly  corbeled toward the center until meeting at the top. 

Oval in shapeSometimes oval in planSometimes oval in profileSometimes oval in both

Parabolic dome•a unique structure.•Bending stress due to the is zero.•However if a point load is applied on the apex of a parabolic dome, the bending stress becomes infinite. •the apex of the dome is stiffened or the shape modified to avoid the infinite stress.

Saucer dome• It’s a low pitched shallow dome •a circular base and a segmental section.•A section across the longer axis results in a low dome, capping the volume.• A very low dome is a saucer dome.  

Different Types Of Domes:Polygonal dome•Also known as domical vaults, cloister vaults, or coved vaults.•Are domes which maintain a polygonal shape in their horizontal cross section.

Umbrella dome•Also known as pumpkin, melon, scalloped, or parachute domes• Are a type of dome segmented by ribs radiating from the center of the dome to the base. 

Building Construction 3

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