STRUCTURE SYSTEMS PROF.DR. SHAFAK EL WAKIL
DEFINITIONS •
A structure is a relatively permanent enclosed construction over a plot of land, having a roof and usually windows and often more than one level, used for any of a wide variety of activities, as living, entertaining, or manufacturing .
• A structure can also be defined as anything built or constructed. • The structural system is that system, which transfers loads through interconnected structural components or members. • The role of any structure system is to transmit the applied loads to the foundations. • Two main kinds of structures : The multistory structures and the large span structures , with a span larger than 20 meters .
CLASSIFICATION OF structures SYSTEMS Surface active structures
Vector active structures
Multistory structures Section active structures
Beam Frame
Flat truss
Curved truss
Space truss
Folded
Tree
Large span structures Slab
Tent
Cable
Plate
Shell
Form active structures
Air
Generally the multistory structures are Section active structural systems . . . systems of rigid, solid, linear elements, in which redirection of force is effected by mobilization of sectional forces.
Typical load transfer systems
Section active structural systems Load transfer systems The loads that a beam or a slab carries are led to columns or walls, which lead the force to the next element.
Portal Frame system The major components of the frame system are horizontal members, vertical members, and some sort of foundation. Similar to the arch, these members work together to resist both vertically and horizontally applied loads .
Cantilever Beam A cantilever is a rigid structural element, such as a beam or a plate, anchored at only one end to a support from which it is protruding Cantilevers can also be constructed with trusses or slabs.
Cantilever Beam /Slab
Multistory structures Load bearing structures o The load bearing structure , is a structure ,where every wall acts as a load carrying element. o A load-bearing wall or bearing wall is a wall that bears a load resting upon it by conducting its weight to a foundation structure. o Punching holes in a wall to connect two rooms damages the structure. o The immense weight of the walls holds the building together and stabilizes it against external forces such as wind and earthquake. o The materials most often used to construct load-bearing walls in large buildings are stone , concrete blocks, or bricks.
Skeleton structures o The skeleton structure , consists essentially of a skeleton or framework, with horizontal (beams) and vertical members (columns) , which support all the loads acting on the building , and through which all loads are transferred . o The skeletal structure cannot enclose the space , therefore enclosing elements are needed. It could afford large openings. o The materials most often used are reinforced concrete for medium rise buildings , and steel for tall buildings. o External wall construction : bricks or hollow blocks in case of concrete structures , cladding in steels structures.
Wall bearing structures
Wall bearing structures
Skeleton structures – classic
Gothic structure
Timber skeleton
Skeleton structures – Medium height buildings – reinforced concrete
Skeleton structures – Tall buildings
A spiral skeleton structure, tall, straight and with strong tension, to meet the requirements of residential, sightseeing and scientific research .
Theory
The äşş REN Building The building takes its form from the Chinese character for person äşş (ren) and combines two buildings, one symbolic of mind and the other symbolic of body. Materials for the building are mainly clear glass and white concrete.
Korea
Abu Dabei
Kuwait
Singapore
India
Abu Dabei
Dubai
Los Angeles
Trump hotel in Dubai
Taiwan
The crescent moon tower in Dubai
Section active structural systems A vault is a roof or floor constructed in an arch form. It can be considered as a long arch thrusting against the supporting walls along their whole length. In an cross vault ,all the thrusts are concentrated where the arches springs. A dome is a vault, having a circular plan and usually in the form of a portion of a sphere, so constructed as to exert an equal thrust in all directions. A dome can rest upon a drum, and can be supported by columns or piers that transition to the dome through squinches or pendentives. Vault & Dome are load bearing elements.
Vector active structural systems . . . are systems of short, solid, straight lineal members, in which the redirection of forces is effected by multidirectional splitting of single force simply to tension or compressive elements
1. Flat trusses
Vector active structural systems Flat Space trusses
Vector active structural systems Flat Space trusses
Vector active structural systems 2.Curved truss A truss having an arch like form but unlike a true arch in that it is free to move horizontally at its base, as in expanding or contracting because of temperature changes.
Vector active structural systems 2.Curved truss
Vector active structural systems 3- Curved Space trusses
Vector active structural systems Curved Space trusses
Vector active structural systems 3.Space trusses
…a system utilizing a three-dimensional truss to resist lateral forces. Unlike a normal truss, in which horizontal, vertical, and diagonal members work together on a single plane, a space truss uses diagonal connections which branch outside of the plane. A space truss usually looks like several interlocking pyramidal outlines.
Vector active structural systems 3.Space trusses
Space trusses Used vertically
Tree structure system The tree theme was inspired by the trees ,that serve as a natural canopy for street-level activities.
Tree structure system
Tree structure system
Tree structure system
Surface active structural systems Systems of rigid planes , able to resist tension , compression or shear, in which the redirection of forces is effected by mobilization of sectional forces. In this system ,usually used for free form designs, the enclosure is the structural system. Example of structures: 1. Folded Plate structures 2. Shell structures : concrete shells , grid shells‌ THE CONCEPT
1. Plate structures A plate is a structural element characterized by two key properties • Its thickness is very small when compared with its other dimensions. • The effects of the loads are exclusively normal to the element's thickness; i.e. parallel to its surface. • Folded plate construction is one in which loads are carried in two different directions. They are usually constructed of reinforced concrete, 3 in to 6 inch thick.
2 Folded Plate structures
2 Folded Plate structures
2 Folded Plate structures
3 Shell structures - Theory • The term shell is used to describe structures occurring strength and rigidity , due to its thin and curved forms such as eggs , tortoise , skull and sea shells.
• A shell structure is a thin curved slab , usually of reinforced concrete ,that functions at the same time as structure and covering . • A thin shell is a shell with a thickness which is small compared to its other dimensions and in which deformations are not large compared to thickness. 1/400 to 1/500 from the span .
3 Shell structures - Forms Surfaces of revolution
Hyperbolic paraboloids (Double curvature surfaces)
3 Shell structures
3 Shell structures
3 Shell structures
4 Grid Shells - Theory • In a Grid shell , a grid pattern replaces the shell material which enables the overall structure to benefit from the combined action of shell and arches and thus to achieve unique shapes. • Same structural behavior as shells, gain their stability from their geometric shapes. • Internal forces are carried by members and therefore have to follow a restricted number of paths. • A plain, continuous shell can resist normal and shear forces while the lattice shell can only resist forces in the direction of the lath i.e. axial forces. • The grid can be made of any material, but is most often wood, plastic or steel. The structural Idea
4 Grid Shells - Wood
4 Grid Shells - Plastic
Wood &Plastic
4 Grid Shells - Steel
4 Grid Shells – Miscellaneous
5 Shell structures – Geodesic Dome • A geodesic dome is a spherical or hemispherical thin-shell structure (lattice-shell) based on a network of geodesics (great circles) on the surface of a sphere or a hemisphere. • The geodesics intersect to form triangular elements, which have local, triangular rigidity, and so distribute the structural stress throughout the geodesic sphere.
5 Geodesic Domes
Form active structures • Are those structures in which load is taken by the form or the shape of the structure. • They are non-rigid, flexible matter shaped in a certain way and secured at the ends. • Can support itself and span space. Only tensile and compressive stresses persists. These are mainly categorized into 3 types: 1 - Bending active structures 2 - Membrane structures 3 - Cable Structures
Tents Structures Pneumatic Structures
1 - Bending active structures The result is a bending-active structure made entirely of extremely thin, elastically-bent strips ,made of plywood ,plastic or any other flexible material.
Basket – Spain pavilion in expo 2015
Timber lathes Plywood strips
Bending active structures
wires
Thin aluminum / plastic sheets
wires
Video
Bending active structures
2 - Cable structures Are a form of long-span structure subject to tension and uses suspension cables for support. There are two different possibilities when using steel cables in roof structures: - using the cables only for suspension of the main roof structure, which can be either conventional . - the steel cables are effective members of the roof structure itself, and not just conveyors of forces from the structure to the anchorages.
Suspension bridge system
Inverted barrel roof system
Double truss roof system
Saddle shape/ Double curvature roof
Bicycle wheel system
Inverted barrel roof system
Suspension bridge system – Stayed bridge Two tower stayed bridge
Suspension bridge system – Stayed bridge Two tower stayed bridge
Suspension bridge system – Stayed bridge Two tower stayed bridge
Suspension bridge system – Stayed bridge Carrying Arch
Suspension bridge system – Stayed bridge one tower stayed bridge
Suspension bridge system – Stayed bridge one tower stayed bridge
Suspension bridge system One tower system
Suspension bridge system- Circular spaces
Cable structures – Bicycle wheel The bicycle-wheel roof involves two layers of tension cables radiating from an inner tension ring and an outer compression ring, which in turn is supported by columns.
Cable structures – cable truss
Cable structures – cable truss Beijing National Hotel’s flowing shape is composed of three distinct rings connected by a single, dynamic surface. Its shiny façade will be made from a lightweight cable-net structure with many windows and skylights providing an ample flow of natural light to the interiors .
Cable structures – cable truss Olympic village -Munich
Membranes - Tent Structures Tent Structure: is a membrane structure , a thin flexible surface, that carries loads through the development of tension forces . Compression elements help to transfer loads to the ground . The form of the tent depends on the location / height of the hanging points . A strong anchorage to the ground is required .
Membranes - Tent Structures
Membranes - Tent Structures
• • • • •
Membranes-Pneumatic / Air Structures A pneumatic or air-inflated structure is a building that derives its structural integrity from the use of internal pressurized air to inflate an envelope made of pliable material ,so that air is the main support of the structure. The structure must be pressurized such that the internal pressure equals or exceeds any external pressure being applied to the structure All access to the structure interior must be equipped with some form of airlock such as a revolving door. Air-supported structures are secured by heavy weights on the ground, or ground anchors, attached to a foundation. The structure can be either wholly, partial, or roof-only air supported.
Membranes-Pneumatic/Air Structures
Membranes-Pneumatic/Air Structures Air beams
Membranes-Pneumatic/Air Structures Higher pressure inside the structure
Membranes-Pneumatic/Air Structures Double skin
The Monorail
GOOD LUCK