PowerPoint Presentation
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