Study on Qubec Bridge Disaster

8/13/2019 Study on Qubec Bridge Disaster

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QUBEC BRIDGE COLLAPSE


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Official name Pont de Qubec

Carries3 lanes of roadway1 rail line1 pedestrian walkway

Crosses St. Lawrence River

Locale Quebec City, and Lvis, Quebec

Maintained by Canadian National Railway

Design Cantilever bridge

Longest span 549 m (1,800 ft)

Total length 987 m (3,239 ft)

Width 29 m (94 ft) wide

Opening date December 3, 1919

cost 25 Million Dollars.
http://en.wikipedia.org/wiki/St._Lawrence_Riverhttp://en.wikipedia.org/wiki/Quebec_Cityhttp://en.wikipedia.org/wiki/L%C3%A9vis,_Quebechttp://en.wikipedia.org/wiki/Canadian_National_Railwayhttp://en.wikipedia.org/wiki/Cantilever_bridgehttp://en.wikipedia.org/wiki/December_3http://en.wikipedia.org/wiki/1919http://en.wikipedia.org/wiki/1919http://en.wikipedia.org/wiki/December_3http://en.wikipedia.org/wiki/Cantilever_bridgehttp://en.wikipedia.org/wiki/Canadian_National_Railwayhttp://en.wikipedia.org/wiki/L%C3%A9vis,_Quebechttp://en.wikipedia.org/wiki/Quebec_Cityhttp://en.wikipedia.org/wiki/St._Lawrence_River


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The bridge is 340 feet high, from the top ofthe cantilever to the water below. Eachcantileverspan is 580 feet long.(15) TheQuebec Bridge accommodates 1 rail line, 3lanes of automotive traffic and 2 pedestrianwalkways.

The Quebec Bridge was declared a historicmonument in1987, by the Canadian &American Society of Civil Engineers and aNational Historic Site on January 24, 1996 bythe Department of Canadian Heritage.


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In 1882 Quebec Bridge Company was granted the contractfor the bridge Due to short finance , nothing was doneuntil 1887 when Quebec Bridge was incorporated withthe Railway Company Theodore Cooper, the mostreputed engineer of that time became the main

consulting engineer for the projectConstruction was contracted to : Phoenix Bridge Company

Initial design was produced by: Peter Szlapka , whichwasre viewed and approved by Cooper. Upon Coopersrecommendation the loading of the bridge[was

increased]by extending the length of thecenter spanfrom[1,600 to 1,800 feet]. The reason being is thatPiers constructed in deeper water would be subject tothe heavy ice floes of the main channel.


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Improper design

Material used

Irresponsibility

Lack of equipment

Lack of budget


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first

Management

problem

Reduced the

number of

piers

Wrong used in

carbon steel

Miscalculation second

Construction

problem

Lack of

budget

Wrong usage

equipment

Overload


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Lack of budget

Reduced the material and research to minimum

Wrong used in carbon steel

Reduced the number of piers

Moved the supports toward to the shores

Miscalculation

Miscalculated the limitation of material and the

whole structure


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Irresponsibility

The chief engineer of the project had never

been to the bridge during the construction.

Ignorance

Somebody discovered the problem but

nobody paid attention to it.


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On August 25, 1907. A loud sound came outfrom The Qubec Bridge constructionarea and

it shook the surrounding houses in vicinity.

A terrible cracking was made and it could beheard in miles. A thick dust raised and the

bridge fell into the St. Lawrence River. In this tragedy, among the 86 workmen, 75

of them lost their life there while only 11 ofthem survived. The entire structure took only15 seconds to collapse.


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The chief engineer, Theodore Cooper did not receiveenough resource from The Government of Canada.

He had to build a bridge with the small budget.

He also wanted to build the greatest bridge in theworld with smallest amount of money. As a result, heignored many problems in order to finish the project.

First of all, he increased the length so that the bridgecould span 61m longer.

Secondly, he decreased the number of piers andmoved the piers toward to the shores. This helped to

reduce the building cost and the depth. Furthermore,he reduced the research and material to theminimum. Although it helped to save lots of money,it would increase the load of the piers and weakenedthe whole structure.


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To build the longest bridge, the engineers ignored many

problems before the construction was started. First of all,because of reducing the cost to a minimum, they did notdo any research in material. Thus, the original materialhad to support an extra load.

Secondly, they brought the piers further shoreward.Although it helped to reduce the building cost, it would

decrease the depth. It was very dangerous because itaffected the foundation of the whole bridge system.

The engineers did not do any research in material. So,theybuilt the bridge with a wrong material, carbon steel.Carbon steel is a cheap construction material. It is heavy,weak and it is very easy to bend. Thus, the load to thebridge was much larger and buckling occurred.


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Buckling is caused by heavy load. When aload is added onto a bridge, the bridge will

be compresses and tensed at the same time.

If it continues, the buckling will occur and the

whole structure will crack. However, it can beprevented by reinforcement.


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I t ft th fi t ll


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Improvement after the first collapse

After the bridge collapsed, the engineers found that it was

not practical to cut cost by reducing the use of material.Also, they discovered that they used a wrong material tobuildtheir bridge.

To prevent the disaster happened again, they chose Nickel

Steel instead of CarbonSteel. Nickel Steel was a strongerand lighter material. For sure, it was more expensive.Theother thing they did was to modify the design. They shiftedthe piers towards the center of the river. Although it would

bring a larger cost, it increased the depth. Thus, thefoundation was better and the bridge could support a largerload.


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Since the bridge collapsed, the engineers did a lotto improve the bridge.

Theoretically, the bridge should not collapseagain. However, the bridge collapsed again duringconstruction nine years later.On September 17,

1916, unfortunately the disaster happened again.

When the jack sbegan to raise the structure inplace between the cantilever arms, the jack broke

and the whole structure crashed into the river.Eleven more deaths were added to theQubecBridgestoll.


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Nickel Steel instead

of Carbon Steel

Change in

Construction method

Redesign done by

seven engineers

Effective equipments

are been used

Improvement

after the

collapse

S h (T i l iff )


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Advantage

Strength (Torisonal stiffness)

Economical in material

Lightweight

Quick to construct

DisadvantageBuckling can occur

It can be unaesthetic


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Study on Qubec Bridge Disaster

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