Introduction to TOS-I Theory of Structure - I
Nov 26, 2014
Introduction to TOS-I
Theory of Structure - I
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Lecture Outlines
Introduction History of Structural Engineering Forms of Structures Materials Loads
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Introduction
STRUCTURAL ENGINEERING
1ST YEAR 2ND YEAR 3RD YEAR 4TH YEAR
ENGG. MECHANICS
THEORY OF STRUCTURES
I
THEORY OF STRUCTURES
II
STRUC. ENGG.
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History of Structural Engineering
Why history is important? One reason why history is important it that the
past has value to our society. History is the narrative of mankind. History when presented properly lends itself to
critical analysis.
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History of Structural Engineering
Greek and Egyptian Temples Made of stone Employed beams and columns Many columns having little useful space between
them
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Greek temple built 2500 years ago
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Greek temples of Poseidonia (now called Paestum) dating from the sixth century BC.
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The Temple of Debod built in early 2nd century BC
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Egypt: Temples of Karnak built 2000 years ago
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History of Structural Engineering
Arch structures were discovered prior to Roman era.
Roman Empire used arches extensively in construction. Stone arches had span of 100 ft and more
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The Colosseum is one of Rome's most distinctive landmarks. Construction of this famous amphitheatre began in 72 AD.
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Arches
Aqueducts
Aqueduct at Segovia in eastern Spain
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The arch of Costantino built in 312 AD
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History of Structural Engineering
From A.D. 500 to A.D.1500, structures that were built continued to employ the stone arch as the major structural forms. Gothic Cathedrals Roof was supported by flying buttresses
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Cathedral from North East Chichester
Flying Buttress
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Cathedral from South East Chichester
Flying Buttress
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History of Structural Engineering Fifteenth and Sixteenth centuries are known as
Renaissance. Galileo (1564-1642)
Concept of force and moments Robert Hooke (1635-1703)
Law of linear behavior of materials Sir Isaac Newton (1642-1727)
Laws of motion Leonhard Euler (1707-1783)
Buckling of columns Palladio
introduced the use of truss
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GALILEO ROBERT HOOKE
ISSAC NEWTON LEONHARD EULER PALLADIO
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History of Structural Engineering Modern Era
Introduction of Iron Industrial Revolution
First major structure built or iron was Severn River Bridge Coalbrookdale.
Suspension bridges Thomas Telford’s Bridge over Menai Straits in
Wales, Brunel’s Clifton Bridge in Bristol, Finley’s Bridge over Merrimack River in
Newburyport, Massachusetts.
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Iron bridge, a cast-iron arch bridge built in 1779 across the River Severn near Coalbrookdale, Shropshire, England
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Thomas Telford built the suspension bridge in the middle in 1826. They had to destroy some of the castle to anchor it to the rock.
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Isambard Kingdom Brunel designs the Clifton Suspension Bridge at Bristol. Two hundred feet above the River Avon, the bridge is 700 feet long.
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History of Structural Engineering
Rank Building - City - Country Year Stories Height
1. Burj Dubai, Dubai, UAE 2008 189* 850m*
2. Taipei 101, Taipei, Taiwan 2004 101 509m
3. Petronas Tower 1, Kuala Lumpur, Malaysia 1998 88 452m
4. Petronas Tower 2, Kuala Lumpur, Malaysia 1998 88 452m
5. Sears Tower, Chicago, USA 1974 110 442m
6. Jin Mao Building, Shanghai, China 1999 88 421m
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Forms of Structures
Structural Forms
Cables Arches Trusses Beams
Surfaces
Membranes Plates Shells
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Cables
Cables stretch well and are light, so they are useful in large structures. They only take tension stresses.
Cables can be crisscrossed and combined with surface materials to achieve light and large structures.
Examples of this technique are Suncoast Dome and Georgia Dome in the United States
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Cable
Road WayCable Anchorage
TowerHanger
Golden Gate Bridge, San Francisco
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Cables Grace Memorial Bridge over the Cooper River
Between Charleston, South Carolina (USA) and Mount Pleasant, South Carolina, stands the Grace Memorial Bridge.
Completed in 1929, the cantilever steel structure has a main span of 1050 ft., or 320 m. and a total length of 3.6 miles or 5.79 Kilometers.
A parallel bridge, with a similar design but a shorter main span, was built in 1966. This allowed the old bridge to be converted to one-way traffic.
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Grace Memorial Bridge over the Cooper River
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Arches
An arch is a curved structure capable of spanning a space while supporting significant weight (e.g. a doorway in a stone wall).
The arch is significant because, in theory at least, it provides a structure which eliminates tensile stresses in spanning an open space.
All the forces are resolved into compressive stresses.
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Chinese Moon Bridge
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Made by Zhao1974 in Hebei Province, China. Built by the architect Li Chun from 595 to 605 AD. World's oldest fully-stone, open-spandrel, segmental arch bridge.
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Triangular Arch Round Arch Segmental Arch
Rampant Round Arch
Lancet Arch Shoulder Flat Arch
Three-Foiled Cusped Arch
Equilateral Pointed Arch
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Horseshoe Arch Three-centered Arch
Elliptical Arch
Inflexed Arch Ogee Arch Reverse Ogee Arch
Tudor Arch
Parabolic Arch
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Truss
In architecture and structural engineering, a truss is a structure comprising one or more triangular units constructed with straight slender members whose ends are connected at joints.
A plane truss is one where all the members and joints lie within a 2-dimensional plane, while a space truss has members and joints extending into 3 dimensions.
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Truss
All members are assumed in axial compression or tension.
Members are joined with the help of frictionless pins.
Loads are applied at joints only.
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Types of Trusses
Common Truss
It is characterized by its triangular shape.
It is most often used for roof construction.
Flat Truss
It gets its name from its parallel top and
bottom chords.
It is often used for floor construction.
Truncated Truss
A combination of the two is a truncated
truss.
It is used in hip roof construction.
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Support structure under the Auckland Harbour Bridge.
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A Vierendeel bridge; note the lack of diagonal elements in the primary structure and the way bending loads are carried between
elements
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Beams
A beam is a structural element that carries load primarily in bending (flexure).
Beams generally carry vertical gravitational forces but can also be used to carry horizontal loads (i.e. loads due to an earthquake or wind).
The loads carried by a beam are transferred to columns, walls, or girders, which then transfer the force to adjacent structural compression members.
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Beams
It requires only vertical supports at ends generally.
It is a compact structure. It’s disadvantage is that it sometimes uses
materials less economically than other structural systems.
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Surfaces
Surfaces
Membranes ShellsPlates
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Membranes
Thin sheets of material
Resist applied loads by tension.
Examples are tents, sails, balloons etc
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Plates
Plates are flat surfaces that transfer loads by bending in a manner similar to beams.
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Shells
Shell is rigid surface that transfers loads in two directions.
The primary difference between a plate and a shell is that the shell has curvature whereas the plate does not. TWA Flight Center, John F. Kennedy
International Airport, New York.
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Materials
Properties of Material
StrengthDeformation
Characteristics
Comp. Tension Resist.
Strength to
weight ratio
Stiff Elastic Ductile
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Materials
Aggregates Steel Concrete Wood Aluminum Fiber Glass Composite Materials etc.
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Loads
Loads
Static LoadsDynamic
Loads
Loads
Dead Live
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Loads
Live Loads
Building Live Loads
Bridge Live Loads
Snow Loads
Wind Loads
Earthquake Loads
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