Steel presentation

VERSATILE MATERIAL

Uses of steel in bridge construction

What is SteelSteel:- Steels are alloys of iron and other elements, primarily carbon high tensile strengths and low costs. Widely used in construction and other applications.

Uses of steel in bridge constructionIndustrial 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

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


Long steel

As reinforcing bars and mesh in reinforced concrete

Railroad tracks

Structural steel in modern buildings and bridges

Wires


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………

The Newark Dyke rail bridgeComprises 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


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


Speed of ConstructionThe 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 minimizedThe light-weight nature of steel permits the erection

of large componentsFor example…..

The Hallen Bridge

A 500T truss bridge near Bristol(England)Carries a single-track railwaySections were shop-fabricated and transported to site where the bridge was fully assembled off line.Transported into position using multi-wheeled Econofreight vehicles


VersatilitySteel 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


Once erected the steel girders provide a platform for subsequent operations.


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

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


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.


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.”


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


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

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.

Examples of steel bridgesMILLAW 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

lifetime of the bridge will be at least 120 years

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.

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

• Golden gate bridge• Structural Steel Quantities

• Tons• Kg• Main Towers• 44,400• 40,280,000• Suspended Structure• 24,000• 21,772,000• Anchorages• 4,400• 3,991,000• Approaches• 10,200• 9,250,000• Total• 83,000• 75,293,000

Steel presentation

Engineering

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