Folded Plates 2o2l5i

FOLDED PLATES Folded plates are assemblies of flat plates rigidly connected together along their edges in such a way so as to make the structural system capable of carrying loads without the need for additional ing beams along mutual edges.  

Types Of Folded Plates 

1- Prismatic : if they consist of rectangular plates.

2- Pyramidal : when non-rectangular plates are used.

3- Prismoidal, triangular or trapezoidal.

Classification          

single. Multiple. Symmetrical. Unsymmetrical. Simple. Continuous. Folded plates with simple ts. Folded plates with multiple ts. Folded plates with opened cross sectional. Folded plates with closed cross sectional.

Folded Plate Behaviour :

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Each plate is assumed to act as a beam in its own plane, this assumption is justified when the ratio of the span "length" of the plate to its height "width" is large enough. But when this ratio is small, the plate behaves as a deep beam.

Principle Folding system represent one category of plane structural surfaces, alongside with plates and slabs. Their special structural behavior is due to their structural subdivision arrangement in pairs which correlate with each other and so they are connected through a shear connection. The structural characteristics of a folding structures depend on the shape of the folding, on their geometrical basic shape, on its material, on the connection of different folding planes and on design of the bearings.

Structural Behaviour The inner load transfer of a loading structure happens through the twisted plane, either through the structural condition of the plate or through the structural condition of the slab.

Roof Types 

 Gable  A very triangular roof, the gable allows rain and snow to run off easily.

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Cross Gable  This is like the gable roof, but has two parts that cross.

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Flat  A flat roof is exactly that - flat. It is easy to build and uses few materials.

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Mansard  A French gable roof. The difference is that the mansard has a flat area at the top instead of being perfectly triangular. These are common in French Chateau houses and Second Empire style houses.

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Hipped  A low-pitched roof that allows rain and snow to run off easily, the hipped roof also allows for large eaves on a building.

Cross Hipped Similar to a hipped roof, but this roof has two parts that cross . 

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Pyramidal  A hipped roof that forms a pyramid shape.

Shed Similar to a gable roof, as it allows rain and snow to run off easily. This is one of the easiest roofs to build. 

Saltbox Similar to a gable roof, but the two sides of it are not symmetrical. 

Gambrel This roof looks more bell-like than triangular when viewed from the side. It is like a flattened gable roof. Many farms have gambrel roofs. 

Pyramidal Roofs Identifiable by its roof shape, the pyramidal-roof house is a one-story building commonly of frame construction. Its square-plan allows for a simple, informal arrangement of rooms. The exterior of the pyramidal-roof house is generally plain, although additions such as ells, porches and corner towers and applied ornamentation lend variety to some examples.

The origins of the pyramidal-roof house are not clear but have been attributed to Southern building traditions. It appeared in the latenineteenth century and remained popular into the early decades of the twentieth century.

Although a pyramid or hipped roof involves more complex framing than a simple pitched roof, it requires fewer longspanning rafters and therefore was less expensive to build than other roof styles.

Pyramidal roof

Hipped roof

The Advantages •Improved resistance to damaging winds. • Due to their aerodynamic shape, a pyramidal roof is less likely to be damaged by high winds then most other roof styles. This improves home safety in areas where tornadoes, hurricanes, or other extreme wind conditions are a concern. •Eaves on all sides.  Because the roof overhangs on all sides, the added shade from the eaves helps keep the home cooler in warm weather. This can lower energy bills by reducing the amount of power the air conditioning needs to cool the home. •Looks good.  With its even sides and overhanging eaves, the pyramidal roof gives the home a striking and distinctive appearance. This roof style looks good from all angles.

•Cost.

The Disadvantages

A pyramidal roof can cost more to install or replace then other roof styles due to the increased surface area of the roof when compared to other styles. This can require more roofing materials and additional labour time.

•Less space.  A pyramidal roof often created less usable interior attic space then other roof styles for the same sized home. This can make attic access more difficult and reduce the amount of usable storage space.

•Drainage and ventilation.  A pyramidal roof generally does not shed water as well as a gable roof. This can make a pyramidal roof more likely to leak than a gable roof. A pyramidal roof is also more difficult to properly ventilate due to its basic design and construction when compared to a gable roof. Both of these problems can be partially overcome by careful construction and proper inspection and maintenance.

Construction A pyramid or square hip roof is shaped like pyramid with four equal-sized triangles rising to meet in the centre. On a rectangular house, the roof will have two rectangular sides and two trapezoidal sides, all rising at the same pitch, typically at 45 degrees.

Forces  in  Pyramid  Surface Under the effect of vertical loads stability is maintained by bending and direct thrust in two directions at right angels, as follows: • Meridian force T1  acting along the triangular sides of the  pyramid. • Horizontal force T2. • Bending moments in the inclined and horizontal directions.