2. What is Steel
Steel:-
Steels are alloys of iron and other elements, primarily carbon
high tensile strengths and low costs.
Widely used in construction and other applications.
3. Uses of steel in bridge construction
Industrial importance on steel:
More than 1.3 billion tons produced annually
Mild steel replaced wrought iron
Hardness, ductility, and tensile strength of the resulting steel is controlled
Various grades defined by assorted standards organizations
4. Why we Uses steel in bridge construction??
The following are some of the advantages that steel can offer;
Long steel
High quality material
Speed of construction
Versatility
Modification and repair
Recycling
Durability
Aesthetics
5. Why we Uses steel in bridge construction??
Long steel
As reinforcing bars and mesh in reinforced concrete
Railroad tracks
Structural steel in modern buildings and bridges
Wires
6.
7. Why we Uses steel in bridge construction??
High Strength to Weight Ratio
strength to weight ratio of is particularly beneficial in poor
ground conditions
Minimum self-weight is also an important factor in
transporting and handling components
shallow construction depths overcome problems with
headroom and flood clearances, and minimize the length of
approach ramps
For example………
8. The Newark Dyke
rail bridge
Comprises a 77m span
bowstring truss
820 tones of S355 steel
The selection of steel was made
because of its high strength to
weight ratio,
The low self-weight also
minimized foundation works
adjacent to the existing rail line.
First UK steel bridge to be
designed for the next generation
of 225 Km/hr trains
9. Why we Uses steel in bridge construction??
Quality
Steel is a high quality material
grades,
shapes
sizes
The testing regime carried out at the steel mills
properly
Pre-fabrication in controlled shop conditions leads to
high quality work at minimum cost.
cutting, drilling, welding, fit-up and painting is easily
permitted
Readily
available
10. Why we Uses steel in bridge construction??
Speed of Construction
The prefabrication of components
time on site in hostile environments is minimized.
The speed of steel bridge construction reduces the
durations of rail possessions and road closures,
public disruption to those networks are minimized
The light-weight nature of steel permits the
erection of large components
For example…..
11. The Hallen Bridge
A 500T truss bridge near
Bristol(England)
Carries a single-track
railway
Sections were shop-
fabricated and transported
to site where the bridge
was fully assembled off
line.
Transported into position
using multi-wheeled
Econofreight vehicles
12.
13. Why we Uses steel in bridge construction??
Versatility
Steel suits a range of construction methods and
sequences.
Installation by cranes, launching, slide-in
techniques or transporters.
Steel gives the Contractor flexibility in terms of
erection sequence and programs.
Components can be sized to suit access
restrictions at the site
14. Why we Uses steel in bridge construction??
Once erected the steel girders provide a platform for
subsequent operations.
15. Why we Uses steel in bridge construction??
Modification & Repair
Steel bridges are adaptable
And can readily be altered for a change in use
They can be widened to accommodate extra lanes of traffic,
and strengthened to carry heavier traffic loads.
Steel bridges can readily be repaired after accidental damage.
A heat treatment technique, based on the theory of restrained
expansion, was proposed by a UK fabricator as a more
economic and less disruptive solution
16. Tamar suspension
bridge (Plymouth)
The needed widening and
strengthening due to increased
traffic loads and volumes
The solution was to replace
the concrete deck with a new
lightweight steel one, and add
steel cantilever sections
The result was that the
widened 5-lane bridge was only
25 tones heavier than the old 3-
lane structure, and was able to
accommodate 44 tone trucks
17. Why we Uses steel in bridge construction??
Recycling
Steel is a ‘sustainable’ material. When a steel bridge reaches
the end of its useful life, the girders can be cut into
manageable sizes to facilitate demolition, and returned to
steelworks for recycling.
18.
19. Why we Uses steel in bridge construction??
Durability
Steel bridges now have a proven life span extending
to well over 100 years.
The potential durability of steel may be summarized
in the following quote by a Mr. J. A . Waddell in
1921:
“The life of a metal bridge that is scientifically
designed, honestly and carefully built, and not seriously
overloaded, if properly maintained, is indefinitely long.”
20. Why we Uses steel in bridge construction??
Durability
Steel has a predictable life, as the structural elements
are visible and accessible
Signs of deterioration are readily apparent
Corrosion is a surface effects are removed by
repainting the affected areas
Alternative form of corrosion protection is the use of
weathering steel
21. Why we Uses steel in bridge construction??
Aesthetics
Steel has broad architectural possibilities
Could be sculptured to any shape or form
The high surface quality of steel creates clean sharp lines and
allows attention to detail
The painting of steelwork introduces color and contrast, and
repainting can change or refresh the appearance of the bridge
to appear as new one
22. Truss Bridge
(Incheon international airport)
This arch-truss bridge connects
incheon international airport to
seoul in korea (above), and has a
main span of 540m. Steel was
considered the only option for
such a high profile site.
23.
24. Examples of steel bridges
MILLAW VIADUCT
Location:- Millau-Creissels, France
Total length:- 2460 m
Longest span:- 342 m
Concrete used:- about 127,000 cubic meter
Steel used:- 19,000 tones of for the reinforced concrete
Required 5,000 tones steel of pre-stressed steel for the cables
and shrouds
26. Preference of steel for Millau viaduct
The advantages of the steel against the original concrete design are:
• light-weight and slenderness of the beam (36 t against 120 t)
• reduction of the depth of the beam to 4.2 m, meaning smaller wind
loads
• improved safety: less work at great height due to pre-assembly on
ground and incremental launching construction
• minimizing the number of stay cables and the size of foundations
• reduction in total costs – the over-riding advantage.
• Within two and a half years nearly 43 t of steel were fabricated for
the beam, the towers and the auxiliary piers.
27. Examples of steel bridges
Sydney harbour bridge:-
Made of steel the bridge contains 6 million
hand driven rivets
The Bridge has huge hinges to absorb the
expansion caused by the hot Sydney sun. You
will see them on either side of the bridge at
the footings of the Pylons
Six million hand driven rivets and 53,000
tonnes of steel were used in its construction