bridge is a structure which covers a gap. a bridge that ... · wooden cantilever bridges were...
TRANSCRIPT
Bridge is a structure which covers a gap.
A bridge that span physical obstacles
such as river ,valley or road is structure
built.
The first bridges consisted of fallen
logs over rivers.
Designs of bridges vary depending on
the function of the bridge
Arch bridges are one of the oldest types
of bridges and have been around for
thousands of years. Arch bridges have
great natural strength.
They were originally built of stone or brick
but these days are built of reinforced
concrete or steel.
Arch bridges are always under
compression.
The tension in an arch isn’t considered
important.
Consequently, materials have that use at
arch bridges, weak tension.
Instead of pushing straight down, the
load of an arch bridge is carried
outward along the curve of the arch to
the supports at each end. The weight is
transferred to the supports at either end.
These supports, called abutments, carry
the load and keep the ends of the
bridge from spreading out.
The load at the top of the key stone makes each stone on the arch of the bridge press on the one next to it.
This happens until the push is applied to the end supports or abutments, which are embedded in the ground.
The design of the arch, the semicircle, naturally diverts the weight from the bridge deck to the abutments.
When the load is divided between a
series of smaller arches.The thrust at
the internal supports balance each
other and thrust is reduced .
A beam or "girder" bridge is the simplest
kind of bridge and two parallel beams
supported by piers of bridge.
Span can be supported by trestle.
Pratt warren
The beam weight pushes straight down
on the piers.
They have bigger internal forces
compared to arch bridges because of
trying to bend.
You can use wooden, reinforced
concrete, prestressed-concrete or steel
as materials.
Large span structures have poor
aesthetic appearance of the truss bridge
but for moderate spans its best to
provide at simple and regular structures.
When loads are applied to a truss at the joints, forces are transmitted only in the direction of each of its member.
Other bridge types have high fabrication cost compared to truss bridges.
Trusses have a high strength to weight ratio and consequently are used in many structures.
Cantilever bridge that built using
cantilever is a bridge .
A cantilever bridge is made from beams
supported on one side only.
The bridge formed with two design
trusses that join in the center by a
connecting member as pin-connected .
The diagram shows a cantilever bridge
supporting a load .
Wooden cantilever bridges were popular in Asia.
The steel cantilever truss bridge was huge breakthrough.
The most famous example of cantilever bridge is the Forth Railway Bridge in Scotland which was the longest span in the world until 1919 .
After The Quebec Bridge was built in Canada.
Native Suspension Bridge
One of the First Discovered in Asia
The first use of suspension
bridge extends to
prehistoric times.
Ancient people used
some plants as like vine
and bamboo for create
suspension bridge.
The first suspension bridge
was built by Chinese people with chains and ropes.
History of Suspension Bridges
Bosphorus Bridge
Undoubtedly , Steel
cable are the most
important factor in the
development of the
suspension bridge.
.
The First modern steel cable
was created by Albert Rop in
1834.
Today, suspension
bridge cables are
made of thousands
of individual steel
wires bound tightly
together.
Steel is strong under
tension, and an ideal material for cables.
A single steel wire, only 0.1 inch thick, can support
load over half a ton without breaking.
The suspension bridge is most preferred bridge to overcome
the long spans.
Suspension bridge
can provide to
overcome the long
spans, but there are
serious drawbacks
They are very flexible
,and traffic load can
lead to a large
collapse.
Thus, a support
beam or a box
beam is added to
help the cable.
Golden Gate Bridge
The Akashi Kaikyo Suspension Bridge is the longest
suspension bridge in the world
Mostly everyone chooses suspension bridge in long
span because Cable wires are cheaper and more
durable than steel beams.
The suspension bridge's carrier system consists of
the following elements:
1. Deck
2. Suspension
cables
3. Main cables
4. Towers
5. The anchor
blocks
• Tower carries the main cables.
• Anchors provides remain to tense of main cable.
• Suspension cables transfer load of deck to main cable .
• Towers can be made from steel or reinforced concrete.
• Usually , deck made from shaped steel cage sytems.
.
How Suspension Bridges Work
The main cables are tense with vertical cables that
attach to the deck.
These cables support the deck of the bridge,
transferring the weight to the towers at the end.
The main cables continue past the tower, and they are anchored past the far ends of the bridge.
They are carefully balanced so that the force pulling
inward on the towers is equal to the force pulling outward.
As a result, the weight pulls directly down into the
base of the tower.
Cable-stayed bridges are a type of suspension bridge.
Cable-stayed
bridges have tall
towers like
suspension bridges,
but in a cable-
stayed bridge, the
roadway is attached
directly to the towers
by a series of
diagonal cables.
A cable-stayed bridge is constructed in much
the same way as a suspension bridge is, but
without the main cables.
Advantages a cable-stayed bridge has
over a standard suspension bridge include
speed of construction and lower cost, since
anchorages are not necessary.
The cable-stayed bridge
is optimal for spans longer
than cantilever bridges
and, shorter then
suspension bridges.
Cable-stayed designs are
used for intermediate-
length spans.
There are no main
cables, as with
suspension bridges,
making cable repair or
replacement simpler.
• There are two major classes of cable-
stayed bridges: harp and fan.
Harp Design Fan Design
Harp Design Cable-Stayed Bridges
In the harp or parallel design, the cables are nearly
parallel.
Fan Design Cable-Stayed Bridges
In the fan design, the cables all connect to or pass
over the top of the towers.