theory
DESCRIPTION
theory of structuresTRANSCRIPT
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THEORY STRUCTURES
THEORY OF STRUCTURES DEALS W/ THE PRINCIPLES & METHODS BY W/C
THE DIRECT STRESS, THE SHEAR AND
BENDING MOMENT AND THE
DEFLECTION AT ANY SECTION OF
EACH CONSTITUENT MEMBER IN THE
STRUCTURE MAYBE CALCULATED
Structural Engineering
Structural Engineering
is a field of engineering dealing with the analysis and design of structures that
support or resist loads.
involved in the design of buildings and large nonbuilding structures
Structural engineers are responsible for engineering design and analysis
Structural Engineering
Structural Engineer may specialize in
bridge engineering,
building engineering,
pipeline engineering,
Industrial structures or
special structures such as vehicles or aircraft.
Building structures
Sydney Opera House, designed by Ove Arup & Partners, with the architect Jorn Utzon
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Building structures
Millennium Dome in London, UK, by Buro Happold and Richard Rogers.
Earthquake engineering
structures
Earthquake-proof and massive pyramid El Castillo, Chichen Itza
Earthquake engineering
structures
napshot of shake-table testing [1] of a base-isolated (right) and a regular (left) building model
Civil Engineering Structures
Civil structural engineering includes all structural engineering related to the built environment. It includes:
Bridges Dams
Earthworks Foundations Offshore structures Pipelines Power stations
Railways Retaining structures and walls
Roads Tunnels Waterway
Civil Engineering Structures Civil Engineering Structures
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Civil Engineering Structures Civil Engineering Structures
Civil Engineering Structures Structural Elements
Any structure is essentially made up of only a small number of different types of elements:\
Columns
Beams
Plates
Arches
Shells
Catenaries
Structural Elements Columns are elements that carry only axial force -
either tension or compression - or both axial force and bending
Beams are elements which carry pure bending only
A beam may be:
cantilevered (supported at one end only with a fixed connection)
simply supported (supported vertically at each end; horizontally on only one to withstand friction, and able to rotate at the supports)
continuous (supported by three or more supports)
a combination of the above (ex. supported at one end and in the middle)
Structural Elements
A truss is a structure comprising two types of structural element, ie struts and ties. A
strut is a relatively lightweight column and
a tie is a slender element designed to
withstand tension forces. In a pin-jointed
truss (where all joints are essentially
hinges), the individual elements of a truss
theoretically carry only axial load
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Structural Elements
Plates carry bending in two directions. A concrete flat slab is an example of a plate
Shells derive their strength from their form, and carry forces in compression in
two directions. A dome is an example of a
shell. They can be designed by making a
hanging-chain model, which will act as a
catenary in pure tension, and inverting the
form to achieve pure compression.
Structural Elements Arches carry forces in compression in one
direction only, which is why it is appropriate to
build arches out of masonry. They are designed
by ensuring that the line of thrust of the force
remains within the depth of the arch.
Catenaries derive their strength from their form, and carry transverse forces in pure tension by
deflecting (just as a tightrope will sag when
someone walks on it). They are almost always
cable or fabric structures. A fabric structure acts
as a catenary in two directions.
Loads on the Structure
live (imposed) loads,
dead loads,
earthquake (seismic) loads,
wind loads,
soil pressure loads,
fluid pressure loads,
impact loads, and
vibratory loads
Live Loads
Live loads are transitory or temporary loads, and are relatively unpredictable in
magnitude. They may include the weight
of a building's occupants and furniture,
and temporary loads the structure is
subjected to during construction.
Dead Loads
Dead loads are permanent, and may include the weight of the structure itself
and all major permanent components.
Dead load may also include the weight of
the structure itself supported in a way it
wouldn't normally be supported, for
example during construction.
Impact Loads
EXTRA OR EXCESS EFFECT DUE TO THE SUDDEN OR ABRUPT
APPLICATION OF LOADS
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Methods of Analysis
FX = 0
FY = 0
M = 0
Statical determinacy
A statically determinate structure can be fully
analysed using only consideration of equilibrium,
from Newton's Laws of Motion.
A statically indeterminate structure has more unknowns than equilibrium considerations can
supply equations for (simultaneous eqn). Such a
system can be solved using consideration of
equations of compatibility between geometry
and deflections in addition to equilibrium
equations.
Materials
Steel
Concrete
Masonry
Timber
Others