Advance structural system
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Space frames are rigid, lightweight structures constructed from interlocking struts arranged in geometric patterns. They can span large areas with few interior supports due to their inherent rigidity from triangular formations that transmit loads as tension and compression. Folded plate structures are assemblies of rigidly connected flat plates that can carry loads without interior beams. They were first used in 1923 for an aircraft hangar roof in Paris and take inspiration from structures in nature like tree leaves. Cable structures have cables as their primary load-bearing elements and are often used in bridges and roofs to transmit loads between supports.
Advance structural system
- 2. TRUSS-LIKE, LIGHTWEIGHT RIGID STRUCTURE CONSTRUCTED FROM I N T E R L O C K I N G S T R U T S I N A GEOMETRIC PATTERN. SPACE FRAMES CAN BE USED TO SPAN LARGE AREAS WITH FEW INTERIOR SUPPORTS. A SPACE FRAME IS STRONG BECAUSE OF T H E I N H E R E N T R I G I D I T Y O F T H E TRIANGLE; FLEXING LOADS (BENDING MOMENTS) ARE TRANSMITTED AS TENSION AND COMPRESSION LOADS ALONG THE LENGTH OF EACH STRUT.
- 3. Folded plates are assemblies of flatplates rigidly connected together along their edges in sucha capable of way that the structural system carrying loads without the need for additional supporting beams along mutualedges. EngineerEudeneFreyssinetperformed the first roof with thefolded structure in 1923asanaircraft hangarat OrlyAirport inParis. 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 analogousto several biological systems such as found at broadleaf-tree leaves, petals and foldable insect wings, are adopted to be employed. Leafof PalmTree Beetle InsectWit h Foldable Wings Seas hel
- 4. Thestructuralcharacteristicsof folding structuresdependon: • Thepattern of thefolding. • Their geometrical basicshape. • Its material. The connection of the differentfolding planes. • Thedesignof the bearings. • Movable form work canbeemployed. • Formwork required isrelativelysimpler. • Design involves simplercalculations. TheConceptOf StiffnessGeneration
- 5. StructuralConditionOfFolding Structures LoadDistributionprocess: At first, the external forces are transferredto the shorter edgeofone folding element. There, the reaction asan axial force is divided between the adjacentelements. Then the forces transferred tothebearings. Classificationoffoldedstructuresbasedonthe materialtheyaremadeof: • Folded structures made ofreinforcedconcrete • Metal foldedstructures • Folded structures ofwood • Folded structures ofglass • Folded structures of plasticmaterials • Folded constructions made in combination of different materials
- 6. Basedongeometricshapefolded structures canbe dividedinto: • Foldedplate surfacesstructures: Prismatic: Rectangularplates. Pyramidal: Non-rectangularplates. Prismoidal: Triangular ortrapezoidal • plates Folded plate framesstructures Spatial folded platestructures TAPEREDFOLDED PLATESFOLDEDPLATERIGID FRAME GEODESICDOME
- 7. • TheInclinedPlates. • Edgeplateswhich must beusedto stiffen the wideplates, • Stiffenersto carrythe loadsto the supportsandto hold the platesin line. Columnsto supportthe structure in the air. • Folded plate structures may be built with tapered elements and only one of the many possible combinationsis 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 jointsfull of concrete.awall of this typecanbemademuchthinner thanaflat wall. T C
- 8. • Theterm "folded plate truss" isintended to indicate the structural actionof this structure. • Therearehorizontal ties acrossthe width only at the endsof the building. • Thethrusts from the triangular crossedarchesare carriedlengthwiseto the ends. • Thetop chordof the inclined truss isformed bythe ridgemember. • Thebottom chordsare the ties at the baseof the sidegablesandthe diagonalsareformed by the sloping valleysat the intersection of the gablesandthe triangular plates. C
- 9. • Anarchwith straight segmentsissometimescalledaRigidFrame. • It isnot asefficient asthe curved archbecausethebending moments aregreater. • Tiesacrossthe plates arerequired at the kneesandat the crown in order to distribute the forces at the endsof eachsegment.
- 10. • Theusualupturned edgeplate canbeeliminated andthe roof structure canbemadeto appear very thin if the edgeplate isreplacedby aseriesof columns. • Theslabbetween columns must be designedasabeamandit maybe convenient to extend the main roofslabasa CantileverCanopy. • Thebeamelement that carries the load of the roof between columns will then be wider and windows under the slabwill havethe samefunction asin the previous examplesof folded plates.
- 11. • 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 sidewall panelsbecausethe walls arebracedat the top. • Only a simple grouted key slot is provided. The tilt-up panels can serve as theirown foundation walls so only a continuousfooting padisusedwith anotch to receivethe tilt-up
- 12. •The size of the frames may be reduced by using a steel tie between the tops of the columns which canbe concealedin the fenestration. Thedimensionsof the plates aredependent 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. • Forexample,assumefor the above structure that the spanis 60 feet and the baywidth 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. 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. Ashell with one curved surface is known as a vault (single curvature ). A shell with doubly curved surface is known as a dome (doublecurvature).
- 14. There are many different ways to classify shell structures but two ways arecommon: • 1. The material which the shell is made of: like reinforced concrete, plywood or steel, becauseeach 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. • 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. TypesofThinConcreteShells 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.
- 17. • A Hypar is a surface curved in two directions that can be designed as a shell orwarped 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 stiffhollow beams that collect & transfer roof loads to the foundations.
- 18. • 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.
- 19. • 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.
- 20. •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.
- 21. • 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) 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
- 22. • 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. • Most 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.
- 23. • 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 statethey 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.
- 24. • Suspended roofs with simple curvature behave l i k e a g r o u p o f c a b l e s s u s p e n d e d i n 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.
- 26. 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
- 29. • 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
- 30. 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.
- 32. The Russky Bridge in Vladivostok