h 02 physical properties.doc

7/27/2019 H 02 Physical properties.doc

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H 02 - Physical properties of building materials:

What you build a structure out of is just as important as how you build it. Different materials havevastly different properties:

Wood:Properties: Strengths- cheap, lightweight, moderately strong in compression and tension.Weaknesses- rots, swells an burn easily

Applications- bridges, houses, two-to three storey buildings, roller coasters

Examples Wooden cabins and houses

Plastic:

Properties: Type- high- strength plastic fabricIngredients long chains of moleculesStrengths flexible, light weight, long lasting, strong in compression and tensionWeaknesses expensive

Applications-umbrellas, inflatable roof over sports arenas, tent structures, inflatable roof

Example:Spectators watching a football game inside the Georgia Dome, Atlanta, Georgia

Aluminum:

Properties: Type aluminum alloyIngredients- aluminum with magnesium and copperStrengths- light weight, doesnt rust, strong in compression and tensionWeaknesses- expensive

Applications airplane wings, boats, cars, skyscraper skin

Example:Petronas Towers, Kuala Lumpur, Malaysia

Brick:

Properties : Type ordinary brickIngredients burned clay

Strengths cheap, strong in compressionWeaknesses heavy, weak in tension

Application- walls of early skyscrapers and tunnels, domes

Example:Original Thames Tunnel-London, EnglandThames Tunnel as it appeared when it opened for traffic, London, England, 1843

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Concrete:

Properties: Type fine-grained concreteIngredients- cement, water, small stonesStrengths- cheap, fireproof and weatherproof, molds to any shape, strong in compressionWeaknesses cracks with temperature changes, weak in tension

Application early arch bridges and domesExample: Pantheon, Rome Italy

Reinforced concrete:

Properties: Type - fine grained-concrete with high- strength steelIngredients steel bars hidden in concreteStrengths- low-cost. Fire-proof and weather-proof, molds to any shape, strong in compression andtensionWeaknesses can crack as it cools and hardens

Applications bridges, dams, domes, beams and columns in skyscrapers

Example:Hoover Dam, Nevada/Arizona boarder

Cast iron:

Properties: Type- cast ironIngredients- iron with lots of carbonStrengths molds to any shape, strong in compressionWeaknesses- weaker than steel in tension, breaks without warning

Application arch bridges, cannons, historic domesExample:

Iron Bridge- Shropshire, England

Steel:

Properties: high-strength steelIngredients iron with a touch of carbonStrengths one of strongest materials used in construction, strong in compression and tensionWeaknesses rusts, loses strength in extremely high temperature

Application cables in suspension bridges, trusses, beams and columns in skyscrapers,roller coasters

Example:Sears Tower, Chicago, Illinois

Vital Statistics:Location: Chicago, Illinois, USACompletion Date: 1973Cost: $150 millionHeight: 1,454 feetStories: 110Materials: Steel

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Facing Materials: Black aluminumEngineer(s): Skidmore, Owings & Merrill

In 1974, the Sears Tower in Chicago assumed the coveted title of world's tallest building, at 1,454feet. It held this title for 22 years until 1998, when the decorative spires atop the Petronas Towers inMalaysia surpassed the Sears Tower by 33 feet. Today, the Sears Tower still boasts the tallestoccupiable floor and the tallest skyscraper roof in the world.

Pantheon Vital Statistics:Location: Rome, ItalyCompletion Date: 123Diameter: 142 feetType: RibbedPurpose: ReligiousMaterials: Concrete, brick

Architect: Hadrian

When Roman Emperor Hadrian decided to build a monument to reflect the power of his empire, hebuilt a dome -- but not just any dome. Hadrian constructed a building out of bricks and concrete withdome that was bigger and more extraordinary than anything anyone had ever seen before. Theenormous building, called the Pantheon, was built as a temple to all the Roman gods almost 2,000years ago. It still exists today, almost entirely in its original form.

The Pantheon is remarkable for its size, its construction, and its design. The enormous domestretches 142 feet in diameter; that's the same as the distance from the Statue of Liberty's sandals ther torch! Given the dome's size and weight, Hadrian's engineers had to find ways to lighten theheavy structure. They scooped out 140 waffle-like depressions, called coffers, in five rows around thdome's base to eliminate some masonry and reduce the dome's weight. They also carved anopening, called an oculus, at the top of the dome, which reduced some mass and created a daily ligshow for which the Pantheon is famous.

The result was an impossibly huge dome, one that would remain the world's largest for 1,300 years.

Here's how this dome stacks up against some of the biggest domes in the world.(diameter, in feet)

Petronas Towers

The Sears Tower is an example of the revolutionary bundled-tube structural design. Tube buildingsgain most of their structural support from a rigid network ofbeams and columns in their outer walls.The rigid outer walls act like the walls of a hollow tube. The Sears Tower is actually a bundle of nine

tubes, and is considered one of the most efficient structures designed to withstand wind. This is agreat design for a skyscraper in Chicago, the "Windy City," where the average wind speed is 16 mileper hour. As the building climbs upward, the tubes begin to drop off, reducing the wind forces on thebuilding. The Tower's heavy weight -- more than 440 million pounds -- is also supported by 114 pilessunk deep into the earth so that they stand firmly on hard, solid bedrock.

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http://www.pbs.org/wgbh/buildingbig/glossary.html#spirehttp://www.pbs.org/wgbh/buildingbig/wonder/structure/petronas_towers.htmlhttp://www.pbs.org/wgbh/buildingbig/glossary.html#concretehttp://www.pbs.org/wgbh/buildingbig/glossary.html#cofferhttp://www.pbs.org/wgbh/buildingbig/glossary.html#masonryhttp://www.pbs.org/wgbh/buildingbig/glossary.html#rigidhttp://www.pbs.org/wgbh/buildingbig/glossary.html#beamhttp://www.pbs.org/wgbh/buildingbig/glossary.html#columnhttp://www.pbs.org/wgbh/buildingbig/glossary.html#forcehttp://www.pbs.org/wgbh/buildingbig/glossary.html#pileshttp://www.pbs.org/wgbh/buildingbig/glossary.html#bedrockhttp://www.pbs.org/wgbh/buildingbig/glossary.html#rigidhttp://www.pbs.org/wgbh/buildingbig/glossary.html#beamhttp://www.pbs.org/wgbh/buildingbig/glossary.html#columnhttp://www.pbs.org/wgbh/buildingbig/glossary.html#forcehttp://www.pbs.org/wgbh/buildingbig/glossary.html#pileshttp://www.pbs.org/wgbh/buildingbig/glossary.html#bedrockhttp://www.pbs.org/wgbh/buildingbig/glossary.html#spirehttp://www.pbs.org/wgbh/buildingbig/wonder/structure/petronas_towers.htmlhttp://www.pbs.org/wgbh/buildingbig/glossary.html#concretehttp://www.pbs.org/wgbh/buildingbig/glossary.html#cofferhttp://www.pbs.org/wgbh/buildingbig/glossary.html#masonry


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Vital Statistics:Location: Kuala Lumpur, MalaysiaCompletion Date: 1998Cost: $1.6 billionHeight: 1,483 feetStories: 88

Materials: Concrete, SteelFacing Materials: Aluminum, Stainless SteelEngineer(s): Thornton-Tomasetti and Ranhill Bersekutu

Until 1998, the world's tallest skyscraper had always been in the United States. But that year,Malaysia's Petronas Towers laid claim to this distinction.

Squeaking past the Chicago Sears Towerby 33 feet, the spiresatop the Petronas Towers peak at aimpressive 1,483 feet. Yet there's a controversy. The highest occupied floor in the Sears Tower isactually 200 feet higher than the top floor of the Petronas Towers, and its antennae stretch higherstill.

Each tower's floor plan forms an eight-pointed star, a design inspired by traditional Malaysian Islamipatterns. The 88-story towers, joined by a flexible skybridge on the 42nd floor, have been describedas two "cosmic pillars" spiraling endlessly towards the heavens.

Reference:

Building Big: Materials LabThis Web site was produced forPBS Online by WGBH.Web site 2000-2001 WGBH Educational Foundation.

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http://www.pbs.org/wgbh/buildingbig/wonder/structure/sears_tower.htmlhttp://www.pbs.org/wgbh/buildingbig/glossary.html#spirehttp://www.pbs.org/wgbh/buildingbig/glossary.html#spirehttp://www.pbs.org/wgbh/buildingbig/glossary.html#storyhttp://www.pbs.org/http://main.wgbh.org/http://www.pbs.org/wgbh/buildingbig/copyright.htmlhttp://www.pbs.org/wgbh/buildingbig/wonder/structure/sears_tower.htmlhttp://www.pbs.org/wgbh/buildingbig/glossary.html#spirehttp://www.pbs.org/wgbh/buildingbig/glossary.html#storyhttp://www.pbs.org/http://main.wgbh.org/http://www.pbs.org/wgbh/buildingbig/copyright.html

h 02 physical properties.doc

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