ADVANCE STRUCTURAL SYSTEM

1. ADVANCE STRUCTURAL
SYSTEM
UNIT V- SPACE FRAMES AND CABLE STRUCTURE

2. SPACE FRAME OR SPACE STRUCTURE
• TRUSS-LIKE, LIGHTWEIGHT RIGID STRUCTURE
CONSTRUCTED FROM INTERLOCKING STRUTS
IN A GEOMETRIC PATTERN.
• SPACE FRAMES CAN BE USED TO SPAN LARGE
AREAS WITH FEW INTERIOR SUPPORTS.
A SPACE FRAME IS STRONG BECAUSE OF
• THE INHERENT RIGIDITY OF THE TRIANGLE;
• FLEXING LOADS (BENDING MOMENTS) ARE
TRANSMITTED AS TENSION AND COMPRESSION
LOADS ALONG THE LENGTH OF EACH STRUT.

3. WHAT ARE FOLDED PLATES
Folded plates are assemblies of flat plates
rigidly connected together along their edges
in such a way that the structural system
capable of carrying loads without the need
for additional supporting beams along
mutual edges.
EngineerEudeneFreyssinetperformed the first roof with thefolded
structure in 1923asanaircraft hangarat OrlyAirport inParis.
FOLDING SYSTEMS IN NATURE
The principle of folding as a tool to develop a
general structural shape has been known for
a long time. Folded structure systems which
are analogous to several biological systems
such as found at broadleaf-tree leaves, petals
and foldable insect wings, are adopted to be
employed. Leafof PalmTree BeetleInsectWith
FoldableWings
Seashell

4. THE PRINCIPLE OF FOLDING
Thestructuralcharacteristicsof folding
structures dependon:
• Thepattern of thefolding.
• Their geometrical basicshape.
• Its material.
Theconnection of the differentfolding planes.
• Thedesign of the bearings.
• Movable form work canbeemployed.
• Form work required is relativelysimpler.
• Designinvolves simpler calculations.
TheConceptOfStiffness Generation

5. STRUCTURAL BEHAVIOUR OF FOLDING
STRUCTURES
StructuralConditionOf Folding
Structures
Load Distributionprocess:
 At first, the external forces are transferredto the
shorter edge ofone folding element.
 There, the reaction asan axial force is divided
between the adjacentelements.
 Thenthe forces transferred to thebearings.
Classificationof foldedstructuresbasedonthe
material theyaremadeof:
• Folded structures made of reinforcedconcrete
• Metal foldedstructures
• Folded structures of wood
• Folded structures of glass
• Folded structures of plasticmaterials
• Folded constructions made in combination ofdifferent materials

6. TYPES OF FOLDED STRUCTURES
Basedongeometricshapefolded structures
canbedivided into:
• Folded plate surfaces structures :
o Prismatic: Rectangularplates.
o Pyramidal: Non-rectangularplates.
o Prismoidal: Triangular or trapezoidal
o plates
• Folded plate frames structures
• Spatial folded plate structures
TAPEREDFOLDED
PLATES
FOLDED PLATE RIGID
FRAME
GEODESICDOME

7. BASICELEMENTSOF
FOLDEDPLATES:
• TheInclined Plates.
• Edgeplates which must be used to stiffen the wideplates,
• Stiffeners to carry the loads to the supports and to hold the
plates in line. Columnsto support the structure in the air.
TAPERED FOLDED PLATES
• Folded plate structures may be built with tapered elements and only one of the many possible combinations is shown
here.
• Afolded plate may be used for walls as a thin structural element by casting each plate flat on the floor and grouting
the joints full of concrete.awall of this type canbemademuchthinner than aflat wall.
T
C

8. FOLDEDPLATETRUSS:
• Theterm "folded plate truss" is intended to indicate the structural action of this structure.
• There are horizontal ties acrossthe width only at the ends of the building.
• Thethrusts from the triangular crossedarchesare carried lengthwise to the ends.
• Thetop chord of the inclined truss is formed by the ridge member.
• Thebottom chords are the ties at the baseof the side gablesand the diagonals are formed by
the sloping valleys at the intersection of the gablesand the triangular plates.
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9. FOLDEDPLATERIGIDFRAME:
• An arch with straight segmentsis sometimes called aRigidFrame.
• It is not asefficient asthe curved arch becausethebending moments are greater.
• Tiesacrossthe plates are required at the kneesand at the crown in order to distribute the forces
at the ends of each segment.

10. EDGESUPPORTEDFOLDEDPLATES:
• Theusual upturned edgeplate canbe eliminated and the roof structure canbe made to appear
very thin if the edgeplate is replaced by aseriesof columns.
• Theslab between columns must be designed asabeam and it may be convenient to extend the
main roofslab asa Cantilever Canopy.
• Thebeam element that carries the load of the roof between columns will then be wider and
windows under the slab will havethe samefunction asin the previous examples of folded
plates.

11. WALLSCONTINUOUSWITHSHELL:
• In this structure the walls are of tilt-up concrete construction; concrete is cast flat on the floor
and raised into place by cranes.
• The walls are designed to be continuous with the roof plates. Tilt-up walls usually are joined by
poured-in-place columns. in this design, columns are not necessary at the junction of the
individual side wall panels becausethe walls are braced at the top.
• Only a simple grouted key slot is provided. The tilt-up panels can serve as their own
foundation walls so only a
continuous footing pad is usedwith anotch to receive the tilt-up

12. THREESEGMENTFOLDEDPLATE:
• Thesizeof the frames may be reduced by using asteel tie between the tops of the columns
which canbe concealed in the fenestration. Thedimensions of the plates are dependent on both the
width of the barrel and on the span.
• The depth of the shell should be about 0.10 times the span and the maximum slope of a plate
should not be greater than 40degrees.
• For example, assume for the above structure that the span is 60 feet and the bay width is 24 feet.
the depth of the shell should be about 6 feet and the horizontal width of each plate with a
three segment plate should be about 8feet.
• the slope of the plates is 6/8, which is about 37 degrees and is satisfactory. the thickness of the
plates could be about 3 ½inches.

13. SHELLS
• Shell is a type of building enclosures.
• Shells belong to the family of arches . They can be defined as curved or angled structures capable
of transmitting loads in more than two directions to supports.
• A shell with one curved surface is known as a vault (single curvature ).
• A shell with doubly curved surface is known as a dome (double curvature).

14. Classification of shells
There are many different ways to classify shell structures but two ways are common:
• 1. The material which the shell is made of: like reinforced concrete, plywood or steel, because each
one has different properties that can determine the shape of the building and therefore, these
characteristics have to be considered in the design.
• 2. The shell thickness: shells can be thick or thin.

15. Thin Concrete Shells
• The thin concrete shell structures are a lightweight construction composed of a
relatively thin shell made of reinforced concrete, usually without the use of
internal supports giving an open unobstructed interior. The shells are most
commonly domes and flat plates, but may also take the form of ellipsoids or
cylindrical sections, or some combination thereof. Most concrete shell structures
are commercial and sports buildings or storage facilities.
Types of Thin Concrete Shells
1. Barrels shells
• The cylindrical thin shells, also called barrels, should not be confused with
the vaults even with the huge similarity in the shape of both structures,
because each of these structures has a different structural behavior as well
as different requirements in the minimum thickness and the shape.
2. Folded plate
• A thin-walled building structure of the shell type.

16. 3. Hyperbolic Paraboloid (Hypar)
• A Hypar is a surface curved in two directions that can be designed as a shell or warped
lattice.
• A hypar is triangular, rectangular or rhomboidal in plan, with corners raised to the elevation
desired for use and/or appearance. The edges of Hypars are typically restrained by stiff hollow
beams that collect & transfer roof loads to the foundations.

17. 4. Various Double Curvature
5. Dome
• 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.

18. 6. Translation Shells
• A translation shell is a dome set on four arches. The
shape is different from a spherical dome and is
generated by a vertical circle moving on another
circle. All vertical slices have the same radius. It is
easier to form than a spherical dome.

19. CABLES STRUCUTRES
•A cable is a flexible structural component that offers no
resistance when compressed or bent in a curved shape.
Technically we can say cable has zero bending rigidity.
•It can only support tensile loading.
•Cables are often used in engineering structures for support
and to transmit load from one point to another when used to
support suspension roofs, bridges and trolley wheels, cables
form the main load carrying element in the structure.
•In analysis of cables the weight of itself cable is rejected . We
assume that cable is flexible and inextensible. Due to its
flexibility cables offers no resistance to shear or
bending.

20. CABLES in STRUCTURES
COMPONENTS
• Lateral bracing
• Suspended highrise structures (tensile columns)
• Single-layer, simply suspended cable roofs
• Single-curvature and dish-shaped (synclastic)
hanging roofs
• Prestressed tensile membranes and cable nets
(see Surface Structures)
• Edge-supported saddle roofs
• Mast-supported conical saddle roofs
• Arch-supported saddle roofs
• Air supported structures and air-inflated
structures (air members)
TYPES
Cable-supported structures
cable-supported beams and arched beams
cable-stayed bridges
cable-stayed roof structures
Tensegrity structures
Planar open and closed tensegrity systems: cable beams,
cable trusses, cable frames
Spatial open tensegrity systems: cable domes
Spatial closed tensegrity systems: polyhedral twist units
Hybrid structures
Combination of the above systems

21. Single-layer, cable-suspended structures
• Simply suspended or hanging roofs include
cable roofs of single curvature and synclastic
shape, that is cylindrical roofs with parallel
cable arrangement, and polygonal dishes with
radial cable pattern or cable nets.
• The simply suspended cables may be of the
singleplane, double-flange, or double-layer
type.
• The concept of simply suspended roofs has
surely been influenced by suspension bridge
construction.NMost buildings using the
suspended roof concept are either
rectangular or round; in other words, the
cable arrangement is either parallel or radial.
However, in free-form buildings, the roof
geometry is not a simple inverted cylinder or
dish and the cable layout is irregular.

22. • In the typical suspended roof the cables (or other member types such as W-sections, metal sheets,
prestressed concrete strips) are integrated with the roof structure. Here, one distinguishes whether
single- or double-layer cable systems are used. Simple, single-layer, suspended cable roofs must be
stabilized by heavyweight or rigid members. Sometimes, prestressed suspended concrete shells are
used where during erection they act as simple suspended cable systems, while in the final state they
behave like inverted prestressed concrete shells. In simple, double-layer cable structures, such as
the typical bicycle wheel roof, stability is achieved by secondary cables prestressing the main
suspended cables.

23. SIMPLY CURVED SUSPENDED ROOFS
• Suspended roofs with simple curvature
behave like a group of cables suspended in
parallel.each cable deforms under its own
load, independently of its neighbours. Curved
roofs of this kind have also been cast in
concrete. The result is a simply curved
suspended shell. Such simply curved concrete
shells, for this is how they act ratherc than as
suspended roofs, are relatively heavy,
whereas the chance of achieving lightness is
the most attractive thing about a genuine
cable structure.

24. • Under load each cable deforms independently
• Transvers stiffeners are introduced
• Under asymmetrical loading the structure will be unstable.
• Complete stability can only be ensured by tying down the ends
of the transverse stiffeners Transverse stiffeners are
introduced

25. Types of Cables
There are generally two types of
cables structures.
• 1- Suspension type Cables.
• 2- Stayed type Cables.
Golden Gate Bridge San
Francisco
Akashi Kaikyo
Suspension Bridge

26. Load Bearing Mechanism of Suspension Bridge

27. EXAMPLE Frederick Severud, with architect Matthew Nowicki, made possible the
design of the suspended roof of the Raleigh Arena in North Carolina (1952).

28. CABLE- STAYED BRIDGES
• A cable-stayed bridge consists of one or more piers, with cables suppoting
the bridge deck.
• Basic idea: reduce the span of the beam (deck) several times compared to
clear span between the piers.
• steel cables-stayed bridges are regarded as the most economical bridge for
spans ranging between between 20 and 400m
• shorter spans: truss or box girder bridges
• larger spans: suspension bridges

29. COMBINATION OF
CABLE AND STRUTS
Under-deck cable-stayed bridges and combined
cable-stayed bridges are two innovative and efficient
types of cable-stayed bridges. In under-deck cable-
stayed bridges, the stay cables are located under the
deck where they are deviated by one or more struts
and are then self-anchored into the deck. On the
other hand, in combined cable-stayed bridges the
stay cables are located both above and below the
deck, deviated by pylons and struts before being self
anchored into the deck.

30. Weitingen Viaduct, Germany
Obere Argen
viaduct, Germany

31. The Russky Bridge in
Vladivostok

32. THANK YOU