SHELL STRUCTURE SYSTEM

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SHELL STRUCTURE


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structure that surrounds something else

is a continuous surface structure

can usually be understood as a set of beams, arches

and catenaries

keep their shape and support loads, even without a

frame, or solid mass material inside

use a thin, carefully shaped, outer layer of material, to

provide their strength and rigidity.

D e f i n i t i o n


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a thin, curved plate structure shaped to

transmit applied forces by compressive, tensile,

and shear stresses that act in the plane of the

surfaces.


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T y p e s : classified by its /curveSingle curvature singly curved shells :

are curved on one linear axis and are part of a cylindeor cone

Type of single curvature shells :

1) Long Barrel Shell / Rampant Vault

2) Short Barrel Shell / Conical Vault

Double curvature doubly curved shells :are either part of a dome or a hyperboloid or revolutio

Type of double curvature shells :1) Hyperbolic Paraboloid

2) Rotational Shell : - Dome

- Hyperboloid


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LONG BARREL SHELL :

the span is large in

comparison to the width

Single curvature shells


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SHORT BARREL SHELL :

length is short than the width


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UPPER/TOP

PART IS IN

COMPRESSION

BOTTOM PARTIS IN TENSION

L o a d D i s t r i b u t i o n
http://localhost/var/www/apps/conversion/tmp/scratch_1//upload.wikimedia.org/wikipedia/commons/8/89/Pringles_chips.JPG


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HYPERBOLIC PARABOLOID :

- is doubly curved

- a set of arches in one direction and a set

of cables, or inverted arches, in the other.

Double curvature shells
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http://eu.lib.kmutt.ac.th/elearning/Courseware/ARC261/images/chapterPics/chapter7pic19.jpghttp://www.jjkostick.com/John_Kostick/pergola_photos.html


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DOME

- surfaces of revolution created by revolving

a curved line about an axis

- spherical : common dome; surface is

generated by rotating an arc of a circle

around a vertical axis

Rotational Shell


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COMPRESSION

TENSION


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COMPRESSION

TENSION
http://en.wikipedia.org/wiki/File:StPetersDomePD.jpg


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http://en.wikipedia.org/wiki/File:StPetersDomePD.jpg


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HYPERBOLOID

straight-line generator isskewed relative to plane

of circular paths


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COMPRESSION

TENSION

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http://localhost/var/www/apps/conversion/tmp/scratch_1//upload.wikimedia.org/wikipedia/commons/9/9d/PuertollanoTermicaEncasur.jpg


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L o a d D i s t r i b u t i o nThe shape of a shell structure spreads forces

throughout the whole structure, which meansevery part of the structure supports only a small

part of the load, giving it its strength.

resist loads on them by direct compression -without bending or flexure.

Its efficiency is based on its curvature (single or

double),which allows a multiplicity of alternatives

tress paths and gives the optimum form for

transmission of many different load types.


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S t a b i l i t y

from its geometrical size

Interaction between shells


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Most suited: concrete reinforced with steel

mesh.

Alternative materials : plywood, metal,

glass-reinforced plasticas shell in boat

and automobile construction

M a t e r I a l


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Attraction of elegant simplicityof curved shell forms that utilize

the natural strength and

stiffness of shell formgreat economy in the use of

material.

Continuity and Curvature -The essential ingredients of a

shell structure

A d v a n t a g e s


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cost of labour, the construction of centering of

shell is very high.A tiny weakness or imperfection on the covering

can cause the whole structure to fail.

When the shell is formed from hot or moistmaterials, uneven cooling can cause some parts to

weaken other parts by pushing or pulling on

nearby sections.

Flat materials are difficult to form into the

rounded shell shape.

Assembly of flexible materials is very precise, so

that seams are strong where the pieces are joined.

D i s a d v a n t a g e s


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T H E E N D

SHELL STRUCTURE SYSTEM

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