Folded Plate Structures Final [PDF]

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INTRODUCTION 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. Folded structures are spatial structures formed by the elements in the plane, different in form and materialization. The straight elements forming a folded construction can be of various shapes: rectangular, trapezoidal or triangular. By combining these elements we get different forms resulting in a variety of shapes and remarkable architectural expression. Tempodrom, Berlin



Folded plates in NATURE



Sea shells



Huge Leaves



Folded plates in EVERYDAY OBJECTS



Origami



Lamps



Window blinds



Hand fans



Basics of FOLDING



The structural characteristics of folding structures depends upon •



The pattern of folding



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Their geometrical basic shape: rectangular, trapezoidal or triangular



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Material



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Connection of different folding plates



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The design of the bearing



Structural behavior of FOLDED PLATES



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External forces are transferred to the shorted edge of one folding element The reaction as an axial force is divided between the adjacent elements Then the force is transferred to the bearings



Bending in folded plates causes top compression and bottom tension Folded plates also tend to flatten out under gravity load, which may be prevented by walls or frames at end supports Tendency of end panel buckling can be resisted by edge beams



Vertical load gets distributed Stabilized against buckling at top and bottom by adjoining plates



FOLDED PLATE STRUCTURE SYSTEMS Folded Plate Structures Linear Additions



Folded Plate Frames Folded Plate Domes



Continuous



Pyramidal Two Hinged



Linear Additions



Polyhedral Three Hinged



Radial Additions



Combination Combination of additions



Barrel - Cylindrical



TYPOLOGY Shape of folded structure affects the transmission of load and direction of relying of folded structures. Based on these parameters we can differentiate the folded structures under: 1. Linear Folded Plate Structure



2. Radial Folded Plate Structure



3. Spatial Folded Plate Structure



Basic Elements of Folded Plate Structures: 1. 2. 3. 4.



Inclined Plates Edge Plates used to stiffen the wide plates Stiffeners to carry the load to the supporters and to hold plates in position Columns to support the structure



TYPOLOGY: TAPERED FOLDED PLATE



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Height at the center of the span is a critical dimension to calculate bending strength. Due to this, the structure is not very efficient and not suitable for large spans.



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Another weak element is the transfer of shear from the smaller end of the plate to the larger end. If a large number of units are used in each span, the transfer of loads may get difficult.



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A folded plate may be used for walls as a thin structural element. A wall of this type can be made much thinner than a flat wall.



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TYPOLOGY: FOLDED PLATE TRUSS



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There are horizontal ties across the width of structure only at the ends of the form. The load from the triangular crossed arches are carried towards the ends.



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The top chord of the inclined truss is formed by a ridge member. The bottom chords are the ties at the base of the side gables.



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This is truly a space structure and its structural action is as shown, therefore, the architectural appearance is more subtle than the usual shell structure.



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TYPOLOGY: FOLDED PLATE RIGID FRAME



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An arch with straight segments is sometimes called a Rigid Frame.



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It is not as efficient as the curved arch because the bending moments are greater.



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Ties across the plates are required at the knees and at the crown in order to distribute the forces at the ends of each segment.



TYPOLOGY: EDGE SUPPORTED FOLDED PLATE



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Roof structure can be made to appear very thin if the edge plate is replaced by a series of columns.



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The slab between columns must be designed as a beam and it may be convenient to extend the main roof slab as a Cantilever.



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Vertical columns at the crown of the gable take the reactions of the plates and the horizontal ties may be eliminated.



TYPOLOGY: WALLS CONTINUOUS WITH SHELL



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In this structure the walls are of tilt-up concrete construction; concrete is cast flat on the floor and raised into place by cranes.



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The walls are designed to be continuous with the roof plates. In this design, columns are not necessary at the junction of the individual side wall panels because the walls are braced at the top.



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The tilt-up panels can serve as their own foundation walls so only a continuous footing pad is used with a notch to receive the tilt-up panel.



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The tilt-up walls are held at the top by the shell and act as vertical beams rather than as Cantilever Retaining.



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TYPOLOGY: THREE SEGMENT FOLDED PLATE



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The forces from the reactions of the sloping plates on these rigid frames will be quite large and at an outside column they will not be balanced by thrusts from the adjacent plates.



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The size of the frames may be reduced by using a steel tie between the tops of the columns which can be concealed in the fenestration. The dimensions of the plates are dependent on both the width of the barrel and on the span.



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The depth of the shell should be about 0.1 times the span and the maximum slope of a plate should not be greater than 40 degrees.



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APPLICATIONS Folded structures have found the application in architectural buildings and engineering structures. Based on the position in the architectural structure, this type of construction can be divided into: roof, floor and wall folded constructions



AS ROOF STRUCTURES : The largest number of examples of folded structures are roof structures. The need for acquiring the larger range and more cost effective structure led to the emergence of this type of structure. The development of spatial structures led to the exceptional formal solutions which directly influenced the aesthetics and visual identity of the building.



Folding a flat surface increases its strength it can be demonstrated when you compare the strength of flat paper and folded paper - Folded roofs are usually made up of reinforced concrete - Flat roofs can be built with minimum thickness with span upto 20 m



Wexler folded plate roof houses



AS FLOORS : Floor structures can be performed by using folded structures. This type of construction is carried out by using different materials: reinforced concrete, steel sheets, wood.



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Mezzanine ceiling can be executed as a wooden folded construction and it represents a parallel "V" crease with elements of veneer or OSB composite, placed between the horizontal elements of cut solid wood. This type of ceiling is called "Kielsteg"



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These metal sheets can also be used for flooring As the folded structure inside the plates provides the Strength



AS WALL STRUCTURES :Walls can be designed and carried out as folded structures, since by folding we get a solid construction that can accept large vertical and horizontal impacts, which enables exceptional height of the wall fabric. This type of folded structures, due to their geometry, provides an economical solution and the rational use of material when compared to the height of the building. Walls made as folded structures can be materialized in reinforced concrete



Notre Dame, Royan, France



AS STEEL SHEET PILES: Securing of foundation pits, especially if the ground is under water, is more frequently performed by using profiled steel sheet piles and this way of security also represents the application of folded.



By using this piles the foundation pits of great depth can be secured. Joints are constructed to allow certain rotation, and thus the opportunity to carry out the walls of steel sheet piles in the bends as well. This type of security of the foundation pits represents a vertical folded structure of steel and this type of pile is called Larsen planks



MATERIALS OF FOLDED SLABS Folded structures made of reinforced concrete : Concrete is the most commonly applied material for creases. A large number of authors define folded construction as the construction made only from reinforced concrete. The reason for this statement is the fact that most of the folded structures are made of this material.



Metal folded structures : Metal folded structures can be derived from trapezoidal sheet or truss. Folded constructions made of metal, steel or aluminum, consist of belts and diagonal bars of infilling. The construction of such folded structures does not require formwork or powerful pumps. Deformation and stability in the design of metal truss structures are of great importance. Height of trapezoidal plate affects the size of a range that can also handle its load capacity.



Folded structures of wood : Folded structures made of wood are easy to transport, handle and assembly. This type of prefabricated folds on the basis of the primary supporting structure of a fold segment can be divided into: panel and truss. Panel folded constructions of wood : Folded constructions of wood are usually formed as a panel 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



OTHER MATERIALS : Other than these many different materials can be used for folded slabs like glass, plastic and combination of different materials . And all these will have different pros and cons and their strengths will vary



A D V A N T A G E S A N D D I S A D V A N T A G E S OF FOLDED-PLATE STRUCTURE



Advantages: -Very light form of construction. To span 30 m shell thickness required is 60mm only -The use of concrete as a building material reduces both materials cost and construction cost. -Longer span can be provided. -Flat shapes by choosing certain arched shapes. -Aesthetically it looks good over other forms of construction Disadvantages: -Shuttering is difficult. -Greater accuracy in formwork is required. -Good labour and supervision necessary -Rise of roof may be a disadvantage.



UNITED STATES AIR FORCE ACADEMY CADET CHAPEL IT IS DESIGNED BY WALTER NETSCH OF SKIDMORE OWINGS AND MERRILL , BUILT IN COLORADO UNITED STATES IN 1962. THE BUILDING HAS STEEL FOLDED PLATE AND TRUSS STRUCTURE COMPOSED OF 100 IDENTICAL TETRAHEDRON FORMING 17 SPIKES. EACH TETRAHEDRON IS CLADDED WITH ALIMUNIUM PANELS WORKING TOGETER WITH TRUSSES TO DISTRIBUTE LOADS THE BUILDING HAS A RECTANGULAR PLAN WHICH HAS LENGTH OF 85 METERS A WIDTH OF 26 METERS AND A HEIGHT OF 45.72 METERS. THE CREASE PATTERN OF THE BUILDING IS DIAMOND PATTERN. THE STRUCTURE IS A TUBULAR STEEL FRAME CONSISTING OF 100 IDENTICAL TETRAHEDRONS, EACH 23M LONG AND WEIGHING 5TN, COATED ALUMINUM PANELS. TETRAHEDRONS 0,30CM ARE SPACED FROM ONE ANOTHER, CREATING HOLES IN THE FRAME ARE FILLED WITH STAINED GLASS 25MM THICK.



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YOKOHAMA INTERNATIONAL PORT TERMINAL IT IS BUILT IN OSANBASHI JAPAN , IN 2002.IN HIS BOOKS MOUSSAVI DEFINES THIS STRUCTURE AS FOLDED PLATE AND TRUSS AND GRIDER WHERE THE STEEL PLATE AND TRUSS FOLDED SURFACE SPANS TWO STEEL GRIDER BRIDGES THAT TOGETHER DEFINES THE LONGITUDINAL SPINE OF THE STRUCTURAL SYSTEM. THE BUILDING HAS A RECTANGULAR PLAN THAT EXPANDS AND COMPRESS ALONG THE CENTRAL LONGITUDINAL AXIS. THE BUILDING HAS LENGTH OF 430 METERS AND A WIDTH OF 70 METERS AND A HEIGHT OF 15 METERS THE BUILDING HAS THREE FLOORS INCLUDING THE BASEMENT. THE FOLDED PLATE APPEARS ON FIRST AND SECOND FOORS CEILING



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Structural Elements ●



The building is steel framed, consisting of main beams (girders) on the two sides and a triangular pyramid (folded plates) system to support the roof and floors.



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These results in a massive column-less interior space, with external walls all made with tempered glass. In short, wood, steel and glass are what constitute the Terminal.



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The strength of the materials minimizes the need for vertical supports and allows for a mostly open floor plan, while the height of the structure allows for a spectacular variety of ceiling conditions in the interior spaces.



VIDY THEATRE IT IS BUILT BY ATELIER CUBE , YVES WEINLAMD ARCHITECTS IN LUSANNE SWITZERLAND.THE STRUCTURE IS DOUBLE LAYERED TIMBER FOLDED STRUCTURE. THE PLYWOOD BOARDS ARE 40 MM THICK AND THERE IS A 25 CM SPACE BETWEEN TWO FOLDED PLATE LAYERS. THE PLYWOOD BOARDS ARE CONNECTED WITH EACH OTHER BY AN INTERLOCKING CHAMFERED DOUBLE THROUGH TENON JOINTS . THE BUILDING AS RECTANGULAR PLAN , LENGTH 28 METERS WIDTH 21 METERS AND A HEIGHT OF 21 METRES THE PATTERN IS COMBINATION OF QUADILATERAL AND TRIANGULAR UNITS THUS CREATING A MIXED PATTERN.



AN INTERLOCKING -CHAMFERED DOUBLE THROUGH TENON JOINTS .



MULIMATT SPORT CENTRE IT IS BUILT BY STUDIO VACCHINI IN ARGAU SWITZAERLAND, THE STRUCTURE IS PRECAST CONCRETE FOLDED PLATE STRUCTURE COMPOSED OF 27 FRAMES UNITS CREATING A RECTANGULR PLAN AND A BOX LIKE FORM. THE BUILDING HAS LENGTH OF 80 METERS WIDTH OF 52 METERS AND HEIGHT OF 11 METERS. THE PATTERN USED IN THIS STRUCTURE IS A MIXTURE OF QUADILATERAL AND DIAMOND SHAPED UNITS THE FOLDED PLATE STRUCTURE CONSISTS OF LINEARLY TRANSLATED 27 ROWS.