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ADVANCED STRUCTURAL SYSTEMS

STRUCTURAL ELEMENTS :: BEAMS, SLABS, ARCHES, DOMES, VAULTS, TRUSSES, PORTAL FRAMES, SPACE FRAMESANMOL KOLLEGAL ( 1101002 )o.Shanmukh ( 1101030 )Satya ( 1101026 )SOURABH REDDY ( 1101035 )Arun kumar ( 1101037 )n. Tejendra ( 1101039 )B.ARCH 7TH SEM SEC ASPA JNAFAU

Abeamis a structural elementthat is capable of withstandingloadprimarily by resistingbending. The bending force induced into the material of the beam as a result of the external loads, own weight and external reactions to these loads is called abending moment.Internally, beams experiencecompressive,tensileandshear stressesas a result of the loads applied to themAbove the supports, the beam is exposed toshear stress. There are some reinforced concrete beams that are entirely in compression. These beams are known asprestressed concretebeams, and are fabricated to produce a compression more than the expected tension under loading conditions

BEAMS

Aconcrete slabis a common structural element of modern buildings. Horizontal slabs of steel reinforced concrete, typically between 10 and 50 centimeters thick, are most often used to construct floors and ceilings, while thinner slabs are also used for exterior paving.In many domestic and industrial buildings a thick concrete slab, supported onfoundationsor directly on the sub soil, is used to construct the ground floor of a building. In high rises buildings and skyscrapers, thinner, pre-cast concrete slabs are slung between thesteelframes to form the floors and ceilings on each level.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.Aribbed slab, giving considerable extra strength on one direction.Awaffle slab, giving added strength in both directions.Reinforcement designAone way slabhas structural strength in shortest direction.Atwo way slabhas structural strength in two directions

SLABS

The arch may be said to have originated with the idea of placing a considerable number of blocks in a concentric arrangement. The wedge-shaped blocks, called voussoirs,hold each other firmly in place and prevent each other from slipping. The voussoirs at the top, orcrown, of the arch convert the downward pressure into lateral (sideways) pressure, orthrust, which is transmitted from the upper voussoirs down around the opening and finally into the ground through the wall orpieron which the arch rests. Not only can considerable distances be spanned in this way, but arches can carry a much heavier load than a horizontal lintel.

The arch is, however, not without its peculiar weakness. The lateral thrust is strongest at thehaunchesof the arch (the part midways between the crown and thespringing). Thekeystone, and the other voussoirs at the crown, presses out against the voussoirs at the haunches, which may buckle and allow the crown to fall if they are not properly buttressed. The lateral thrust at the haunches can be counteracted by the thrust of arches placed to either side, as in anarcade, but, unless the arcade is circular, the lateral thrust of the arches at the end must finally be counteracted by the sheer mass of an abutment.

ARCHES

Types ofarches:Arches are constructed in four basic shapes that frame and support doors, windows, porches, and other wall openings:Flat archTriangular archRound archPointed arch

ARCHESFlat arch:An arch having a horizontal intrados with voussoirs radiating froma centre below, oftenbuilt witha slightcamber to allow settling is called a flat or jack arch.

Triangular arch:It is a primitive form of arch consisting of two stones laid diagonally to support each other over an opening. Hence, the span is limited by the size of the available material.

French arch:A flat arch withvoussoirs inclined tothe same angle at each side of the centre. The mortar joints do not, therefore, radiate to a common centre. Not, technically, a proper arch, and of weak form.

Avaultis a ceiling of brick, stone, or concrete built in the principle of the arch. Atunnel vault, orbarrel vault, is a tunnel-like, semi-cylindrical extension of an arch, which may be thought of as an unbroken series of arches pressed together, one behind the other. It cannot be lighted except at the ends without being structurally weakened, because, as in an arch, continuous abutment must be applied to absorb the thrust carried down along the haunches to the walls supporting it. However, arches may be introduced in the supporting walls and transverse ribs may be inserted in the vault to concentrate thrust at a few strongly buttressed points, thereby permitting a reduction of weight and thrust in the segments of vaulting between the ribs.If a barrel vault is intersected at right angles by another barrel vault of the same size, across vault, orgroin vault, is formed. This is a very efficient form of vaulting allowing full illumination from the sides. Groin vaults also allow a great saving in material and labour over the simple barrel vault; thrust is concentrated along the groins (the four diagonal edges formed along the points where the barrel vaults intersect), so the vault need only be abutted at its four corners.

VAULTS

Types of vaults:

Barrel Vault: A barrel vault is the simplest of the vaults and is the base design for many vaults that have a more intricate design. It consists of an on-going series of semi-circular arches. One is directly behind another, causing it to look like a half of a barrel. In some instances, it is described as resembling a tunnel.Groin Vault: A groin vault is created by two barrel vaults intersecting at right angles. The arches of groin vaults are round or pointed. It is also known as a cross vault.Rib Vault: A vault reinforced by masonry ribs is known as a rib vault. When this type of vault has two masonry ribs dividing it into four sections, it is called a quadripartite rib vault. A vault divided by three masonry ribs that make six sections is called a sexpartite rib vault.

VAULTS

Domes are curved architectonic structures with no angles or corners, similar to the upper half of a sphere. Despite their apparent fragility, domes are strong structures and have been used in buildings since ancient times, according to PBS Online. In Europe, the earliest domes were made of stone. The Roman Pantheon, built almost 2,000 years ago, is a good example of early dome engineering. Indigenous peoples in Ethiopia and other places have used curved bows to create their huts, creating a primitive yet effective dome.

DOMES

Geodesic Dome:The geodesic dome was invented in the 1950s by American engineer and architect Buckminster Fuller, according to PBS Online. This type of dome is structured on triangles and other geometric shapes instead of the arches. The Epcot Centre in Orlando, the Caspary Auditorium in New York and the Eden Project in England are examples of geodesic domes.

DOMES

Monolithic Dome:The monolithic dome is made of one solid piece of material. Its construction begins with a circular concrete foundation, where a canvas "air form" is attached to the slab. The canvas is then inflated using special fans, thus forming the shape of the dome. After that, the interior is covered with a layer of polyurethane foam insulation . A steel bar is enclosed in the foam to give support to the dome. Finally, a special mix of concrete is spread over the interior of the building, reports the Architecture Week website.

DOMESBow Dome:The bow dome is made of wood bows, which can be substituted by aluminium, and canvas. This type of dome is rather archaic, yet efficient. It represents the first habitation built by humans, according to website Simply Different. There are different types of bow domes, which depend on how the bow is placed. Half sphere or unibow is the most common, but has some disadvantages, which include the almost horizontal roof angle at the top, not ideal under snow, for instance. Cross-tie, peak-tie and bell are other types of bow dome, more appropriate for regions with lots of rainfall or snow.

Atrussis astructurecomprising one or more triangular units constructed with straight members whose ends are connected at joints referred to asnodes. External forces and reactions to those forces are considered to act only at the nodes and result in forces in the members which are eithertensileorcompressiveforces. Moments (torsional forces) are explicitly excluded because, and only because, all the joints in a truss are treated asrevolutes.A planar truss is one where all the members and nodes lie within a two dimensional plane, while a space truss has members and nodes extending into three dimensions.Characteristics of trussesA truss is composed of triangles because of the structural stability of that shape and design. A triangle is the simplest geometric figure that will not change shape when the lengths of the sides are fixed.In comparison, both the angles and the lengths of a four-sided figure must be fixed for it to retain its shape.

TRUSS

There are two basic types of truss:Thepitched truss, orcommon truss, is characterized by its triangular shape. It is most often used for roof construction. Some common trusses are named according to theirweb configuration. The chord size and web configuration are determined byspan,loadandspacing.Theparallel chord truss, orflat truss, gets its name from its parallel top and bottom chords. It is often used for floor construction.A combination of the two is a truncated truss, used inhiproof construction. A metal plate-connected wood truss is a roof or floor truss whose wood members are connected withmetal connector plates.

TRUSS

Portal frames are single storey, single( or multi-bay) frames with pitched or flat roof. Fabricated from universal beams, it is an ideal structural solution in many circumstances, regarding its economic and structural efficiency. The system is specially ideal for industrial buildings due to its ability to span large areas of unobstructed open space within its building envelope. This is made possible through the design and use of refabricated steel sections. Technological advance in the footing system also cooperate for the large span achieved due to their ability to carry greater loads (or its efficiency to transfer and distribute the loads to the foundation).

PORTAL FRAME

Three major elements are; cladding for both roof and walls; secondary steel to support the cladding and form framing for doors, windows and the like;and the main framework of the structure, including all necessary bracing. In addition, the building requires appropriate footings designed to transmit all the load to the foundations( supporting soil).

PORTAL FRAME

A space frame is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Space frames usually utilize a multidirectional span, and are often used to accomplish long spans with few supports. They derive their strength from the inherent rigidity of the triangular frame; flexing loads (bending moments) are transmitted as tension and compression loads along the length of each strut. Space frames are an increasingly common architectural technique especially for large roof spans in modernist commercial and industrial buildings.Some Space Frame Applications include:Hotel/Hospital/commercial building entrancesCommercial building lobbies/atriumsParking canopies

SPACE FRAMES

Advantages of space frame systems over conventional systems:

Random column placement

Column-free spaces

Minimal perimeter support

Controlled load distribution

Design freedom

Supports all types of roofing

SPACE FRAMES