Dome shells have a rounded roof shape with a circular base like an arch in all directions. They were first used widely in the Middle East and North Africa and spread with Islamic architecture. Domes have double curvature, making the structure stiffer and stronger than a single curved surface like a barrel shell.
Beams experience bending forces from loads. Common beam materials include steel, concrete, wood, and composites. Beams are characterized by their cross-section profile, length, and material. Common profiles include I-beams, C-channels, hollow sections, pipes, and angles. Beams experience internal compressive, tensile and shear stresses.
Concrete slabs are commonly used as floors and ceilings
3. Dome shells–might be domical shell
structures
A rounded roof, with a circular base, shaped like an arch in all directions.. First
used in much of the Middle East and North Africa whence it spread to other
parts of the Islamic world, because of its distinctive form the dome has, like the
minaret, become a symbol of Islamic architecture.
Dome has double curvature and the resulting structure is much stiffer and stronger than
a single curved surface, such as a barrel shell
7. Design
For a suspended slab, there are a number of designs to improve the strength‐to‐weight ratio. In all cases
the top surface remains flat, and the underside is modulated:
Corrugated, usually where the concrete is poured into a corrugated steel tray. This improves strength
and prevents the slab bending under its own weight. The corrugations run across the short dimension,
from side to side.
A ribbed slab, giving considerable extra strength on one direction.
A waffle slab, giving added strength in both directions.
Reinforcement design
A one way slab needs moment resisting reinforcement only in its short‐direction because the moment
along long axes is so small that it can be neglected. When the ratio of the length of long direction to
short direction of a slab is greater than 2 it can be considered as a one way slab.
A two way slab needs moment resisting reinforcement in both directions. If the ratio of the lengths of
long and short side is less than two then movement in both direction should be considered in design.
Construction
A concrete slab may be prefabricated or in situ. Prefabricated concrete slabs are built in a factory
and transported to the site, ready to be lowered into place between steel or concrete beams. They
may be pre‐stressed (in the factory), post‐stressed (on site), or unstressed. It is vital that the
supporting structure is built to the correct dimensions, or the slabs may not fit.
In situ concrete slabs are built on the building site using formwork ‐ a type of boxing into which the
wet concrete is poured. If the slab is to be reinforced, the rebars are positioned within the
formwork before the concrete is poured in. Plastic tipped metal, or plastic bar chairs are used to
hold the rebar away from the bottom and sides of the form‐work, so that when the concrete sets it
completely envelops the reinforcement. For a ground slab, the form‐work may consist only of
sidewalls pushed into the ground. For a suspended slab, the form‐work is shaped like a tray, often
supported by a temporary scaffold until the concrete sets.
The formwork is commonly built from wooden planks and boards, plastic, or steel. On commercial
building sites today, plastic and steel are more common as they save labour. On low‐budget sites,
for instance when laying a concrete garden path, wooden planks are very common. After the
concrete has set the wood may be removed, or left there permanently.
In some cases formwork is not necessary ‐ for instance, a ground slab surrounded by brick or block
foundation walls, where the walls act as the sides of the tray and hardcore acts as the base.
22. consequence the performance of these
structures is often less than ideal when
judged by technical criteria.
• structure as architecture
o buildings which consisted of structure and
only structure, like igloo and tepee.
o eg. palazatto dello sport, italy
• structure as form generator
o The term structure as form generator describes a relationship
between structure and architecture in which structural
requirements are allowed to influence strongly the forms of
buildings even though the structure itself is not necessarily
exposed.
o In this type of relationship the configuration of elements
which is most sensible structurally is accepted and the
architecture accommodated to it.
o the form‐generating possibilities of structure contribute to an architectural style.
o The vaulted structures of Roman antiquity are an example. The large interior spaces of
the basilicas and bath houses of Imperial Rome were roofed by vaults and domes.
Structure and form
Structural forms that ignores basic knowledge of the relationship between geometry and structural
behaviour results in a lack of structural efficiency. In the ‘high tech’ architecture of the 1980s for
example, the structural elements discipline the plan of the building and form an important part of the
visual vocabulary. In the early Modern buildings of Gropius, Mies van der Rohe, Le Corbusier and
others, the forms which were adopted were greatly influenced by the types of geometry which were
suitable for steel and reinforced concrete structural frameworks.
Structures that give rise to unique building forms either come under the category of semi or fully form
active structures. These structures justify the use of structural elements for the design complexities they
are faced with, and these structural elements define a new aesthetic style for the building.
Fully form‐active structures are normally used only in circumstances where a special structural
requirement to achieve a high degree of structural efficiency exists, either because the span
involved is very large or because a structure of exceptionally light weight is required.
They have geometries which are more complicated than post‐and‐beam or semi‐form‐active
types and they produce buildings which have distinctive shapes.
Included in this group are compressive shells, tensile cable networks and air‐ supported tensile‐
membrane structures. Form‐ active shapes are frequently chosen for the compressive
elements as well as for the tensile elements (see Fig. 7.18).
27. Double layer truss geometries are used whenever there are large or concentrated loads, column
supports, or for extremely long spans.
The doubling of the layers of the lattice grid shell, used for increased stiffness
Q. Describe the following structural systems with neat sketches. (2012)Braced domes
The rise of a braced dome can be as flat as one seventh of the diameter or as high as three fourths of the
diameter, which will constitute the greater part of a sphere. For diameters larger than 60 m, double‐layer
grids are recommended. The ratio of the thickness to the diameter of double‐layer braced dome is in
the range of 1/30 to 1/60; for long spans the thickness can be as small as 1/100 of the diameter.
Out of a large variety of possible types of braced domes, only four or five types proved to be frequently
used in practice.
1. Ribbed domes (write from notes)
2. Schwedler domes
34.
PLATE TYPE DOMES
Plate-type domes are usually described as domes, totally or partly consisting of planes with more than
3 edges, braced by structural cladding such as plates or by bars in a triangular pattern. It seems that
this concept may be extended to regarding the plate dome, or plate structure in general, as an
independent and just as basic a structural family as the lattice structure, so basic in fact that it is the
exact dual of the lattice structure.
NETWORK DOMES
39.
Panel folded constructions of wood
Folded constructions of wood are usually formed as a panel. Wooden panel folded constructions
based on their primary structure can be divided into:
full wall panels,
panels with grid supporting structure,
panels with framework (panel) supporting structure,
panels with arch supporting structure.
Joints between the wooden panels are articulated; therefore it is necessary to install additional
stiffening elements ‐ the diaphragms, which can be set as full‐wall wooden elements or sticks
(wooden or metal).
Full‐wall panel folded constructions of wood
The elements of full‐ wall panel folded structure are constructed as compact elements of solid
timber or laminated elements ‐ plywood and the panel frame structure covered with veneer sheets.
Full wall element consists of cross‐laminated wood panels.
Folded construction of wooden trusses
Elements of folded structure could be formed of wooden trusses. By combining the trusses we can
get different forms of folded structures. Connection of trusses is done on site. Band sticks in the
deflections and hips of folded structure and infilling bars are made from solid timber or glued
laminated wood. The choice of dimensions of the cross‐ section of the rod of wooden truss is
affected by: the range, load, shape and dimensions of the element of a fold. Static calculation
determines the precise dimensions of each rod in the lattice of a wooden element. When installing,
the packages are formed on the ground.
Folded structures of glass
Glass as a building material has intensively been applied as a structural element. By using glass alone
or in combination with other materials, wall, roof and floor constructions can be made. Independent
glass plate under the force of pressure is deformed ‐ it flares up, and therefore, in order to prevent
the deformation of a glass plate we associate it with another element. If we want to prevent this
deformation with another glass plate, then this new feature is set at an angle relative to the base
glass plate, thus forming a folds shape and achieve a spatial rigidity of the glass element. The
possibility of making constructions of glass for a cylindrical folded structure is up to range 12 m. This
construction is designed with glass triangular elements with links realized with metal brace. This
type of joint connection allows mutual stiffening of adjacent panels.
Folded structures of plastic materials
Products made of polyester resin had been widely used in the second half of the twentieth century.
This material has also found its application and in production of folded structures. There are
examples in practice where folded constructions have been derived from individual flat plate
elements or in combination of spatial elements of "V" or "Λ" shape folds with a flat plate elements.
This type of folded structures is made of polyester resin has found application in the construction of
garden centre facilities.
Action by which folded plate structure resists load or structural action of folded plates:
Folded plates distribute loads along the surfaces of a plate and along the seams between the folds
,across three dimensions ,producing structures composed of surface and linear elements.folded
plates .folded plates can be made of steel reinforced concrete or,steel plate or both in conjunction
with and reinforced by,,a linear truss system.folded plates built of steel reinforced concrete or steel
direct loads along their surfaces.in addition the gradual sub‐division of reinforced concrete or steel
48. Opening elements Windows
Anchors
Fastening elements
Connecting pieces
Q) In what situations curtain walls are used? How many types of curtain walls are popularly used?
Illustrate their components with sketches.
A curtain wall system is an
- outer covering of a building
- that is non‐structural (carries only its own dead weight and wind loads)
- But merely keep the weather out and the occupants in.
As the curtain wall is non structural
- Can be made of a lightweight material reducing construction costs.
- Mostly glass is used as the curtain wall ‐ a great advantage is that natural light can penetrate
deeper within the building.
Curtain walls were introduced due to the following needs:
• Smaller wall footprint = resulting in extra floor area available for occupants
• Parallel scheduling = resulting in faster erection
• Lighter structure = resulting in material and transportation savings
• Structural flexibility= resulting in easier seismic engineering
• Improved light access = resulting in a more flexible and economical architectural layout
• Structural independency= resulting in a more flexible architectural layout
Their development was allowed by industrialization and growth of prefabrication concept in the early
19th century and expressed in the first large fully glazed structure (Crystal Palace, London, United
Kingdom) in the year 1851 and the first independent frame building ( Menier Chocolate Factory near
Paris, France) in the year 1871.
Types of Curtain Walls Systems:
A wide variety of materials and designs are available to meet different requirements in curtain wall
construction. Curtain walls are classified by how they are built.
Five systems implemented most frequently:
1. Stick system;
2. Unit Panel system/ Unitized system;
3. Unit Mullion system;
4. Column cover and Spandrel systems; and
5. Point‐loaded Structural glazing systems.