The Effect of Structural Height on Building Stability
Researched by Krista G.
2001-02



PURPOSE

The purpose of this experiment was to determine the effect of building proportions (height) on the stability of a structure.

I became interested in this idea after the tragedy on September 11th, 2001 in which two skyscrapers collapsed. I wanted to find a way to build safer buildings. 

The information gained from this experiment will help architects and builders know how to build skyscrapers more efficiently. It will also help people who work in skyscrapers to be safe.




HYPOTHESIS

My hypothesis was that as building height is increased, building stability is decreased. 

I base my hypothesis on a quote from World Book Young Scientists. "One of the problems that engineers face when designing a skyscraper is the strength of wind." Wind is a type of impact. I am going to test that as a size of impact.
 

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 EXPERIMENT DESIGN

The constants in this study were:

  • -The type of material (Balsa)
  • -The amount of Balsa (100 cm)
  • -The size of the force of impact
  • -The construction method
  • -The foundation material (clay)
  • -The size of cardboard (8*8)
  • -The place where the pendulum is dropped
  • -The size of pendulum string
  • -The amount of clay (1kg)
  • -How many models of each (5)
  • -How many different models (4)


The manipulated variable was the building proportions. (height)

The responding variable was the number of impacts the building withstood before failing.

To measure the responding variable I counted the number of impacts before failure of the structure.




 MATERIALS
 
QUANTITY  ITEM DESCRIPTION
1 kg. Clay/ playdough
140 cm Balsa wood (15 cm. Per. Skyscraper)
15 Sheets of cardboard (18X18 cm)
10  washers (force of impact)
30 cm 1.5 cm wide binding cloth
counter with an over hang
1 Hot glue gun
10  Hot glue gun sticks 
Marker or pencil
1 Ruler with cm
grams scale
1 Small clamp
Medium clamps

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PROCEDURES

1. First get an 18x18 (cm) piece of cardboard
2. Measure and draw a 5x5 (cm) square in the center of the sheet of cardboard
3. Get some clay/ playdough and put 1 1/2(cm) thick of clay/playdough within the square. Filling up the whole square.
4. Measure the balsa wood in sticks that are 5 cm long, 4 sticks will be needed.
5. Mold the sticks in the four corners of the clay / playdough (Be sure to keep the clay or playdough a constant, each will work, the playdough just canít be soft.)
6. Connect two 6 cm sticks of balsa wood together in an equal X shape by using Elmer glue and gluing it in the center. This is to put between the empty spots between the 4 sticks of balsa wood, which means it will need 2 sets of two, equaling to be 4 sticks total.
7. On the opposite sides the side which is the face of the building where the 5cm sticks are closest together, you will need another X set but only the size of the sticks will be 4cm. 
8. Measure a 5x5 (cm) thin sheet of balsa wood
9. Put hot glue on the tops of the 4 corner sticks and carefully set it on the top
10. The frame is finished, but it  will need to dry (including the playdough, it is dry when it is hardened)
11. Make a force of impact by taking one of the ten washers and tie it on the end of the 40-cm binding cloth.
12. When it is tied in a strong knot, pile the other 9 washers on top of each other above the first washer that was tied.
13. Use a gram scale and weigh the weight (it should weigh approximately 50 grams)
14. Now it is ready to test!
15. Use two medium clamps and clamp the cardboard down onto the counter.
16.  You will need some kind of over hang (ex. A cabinet over a counter) and with a small clamp, clamp the binding onto the over hang. (Make sure the weights are in the direct center of the structure.
17. Pull up the weight and make it so it is perfectly straight (use a ruler to measure the straightness) 
18. Then release 
19. If the skyscraper is unharmed the impact then keep trying until it shows signs of failure.(donít forget to keep count of how many times it took before failure) 
20.  When building the 10 cm, and 15-cm skyscraper, build it the same as the 5-cm structure only build onto the top the same way you built the bottom. Only instead of having a clay/playdough foundation, just one strip of hot glue for the corner sticks to be able to stand.

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  RESULTS

The original purpose of this experiment was to determine the effect of building proportions (height) stability of a structure.

The results of the experiment was that the 10 cm structure could withstand the most impact. 

See the data and graphs.




    CONCLUSION

My hypothesis was as skyscraper height is increased, building stability is decreased. 

The results indicate that this hypothesis should be rejected because of this, when I averaged out all the different sizes of skyscrapers after all my trials I found that the 10 cm skyscraper withstood the most force.

Because of the results of this experiment, I wonder if I had made bigger buildings the results would be different, or if I would have made the foundation out of cement, would that have made a difference?

If I were to conduct this project again I would have a better building design, more trials, I would repeat the whole experiment about two to three times, and have a better source of impact instead of just washers. I also could have a more accurate grams scale, and have a few more variations of skyscraper sizes.
 

Research Report 

Introduction

Shelter is a very important for human life. Humans must maintain a body temperature close to 98.6°F. without shelter this is hard to do in the cold of winter and in the heat of summer.  Without shelter people might not have jobs places to work, or play. Shelters need to be safe. Skyscrapers are especially vulnerable to forces like wind due to their tall, skinny, shape. 

A Skyscrapers main parts

A skyscraper is a very tall structure with about four main parts to make it stand. The first of the four is the "foundation." Which needs to be carefully balanced because any wrong measurement can make the building fall. It is made of dirt, layers of different other things or cement mixed with water. Constructors use things, such as this because it needs to be soft to be able to hold the heaviness of the skyscraper.

The next part constructorís work on is the steel "frame." The average weight of a frame is about 100,000 tons. The frame needs to be one of the strongest and sturdiest parts of a skyscraper, because it is the skeleton of the structure just like the skeleton of our bodies. Which means that that is the key to making the whole building safe and being able to stand.

Next, comes the exterior or in outside cover. This provides walls, covering and roofing to the building. Constructors make sure that the material they use for the exterior, is fire proof in case the building was to catch fire. The best material for looks and for fire safety is glass. Some skyscrapers try to decorate the exterior a little extra than normal so it will stand out in appearance. Some other types of exterior materials are bronze, aluminum, or painted steel. These types arenít as decorative as glass, but they work pretty well for an exterior.

The very last thing that is needed in building a skyscraper is filling up the interior. The first thing done in filling the interior is planning where outlets and other electrical matters that could cause problems without them. Then they bring in the big electronic items, such as an elevator. Architectures need to make sure they install enough smoke detectors and water sprinklers. Skyscrapers must be very safe. So constructors replace major parts of a skyscraper, every ten years. 

Tallest Skyscrapers

Many local skyscrapers seem very tall in height, but when you compare them to the three tallest skyscrapers in the world, they are much smaller. The tallest skyscraper is located in Kuala Lumpur, Malaysia. They are called the Petronas Towers, 452 meters (1,483 feet) making up 88 stories. The second tallest tower is the Sears Tower, located in Chicago, 442 meters (1,450 feet) and 110 stories. Until recently the third tallest skyscraper was also 110 stories too, but only was 417 meters tall (1,368 feet) and was located in New York. That was the Twin Towers, which were used as a World Trade Center.

Force

Force makes a difference in objects, their width, shape size etc. For example, moving one direction to another, or moving slow to fast. All of these can have an effect on any kind of object.  The larger the mass of force something has on it, the less acceleration it will have. Or the smaller mass of force something has on it, the more acceleration. The acceleration and mass something has on it can be measured. Gravity and force both work together and hold things down. The study in which force is under is called, "mechanics." When skyscrapers have to do with force is the force that wind has on them. That is a problem to engineers when building a skyscraper. The force of wind can give a heavy burst of impact on the face of the building which can cause much damage depending on the mass of force that is given.

Impact

The definition of impact is, "striking of one body against another." That is one example of how impact works. Another example is, impact will come at the exact same time as a collision. So in a car crash when the collision happens, so does the impact, denting comes by the force of impact. A law of impact states that "when two bodies strike against another it is not the same after the force of impact has come upon the body. If a strong force of impact came in contact on the face of a skyscraper the impact could cause a lot of damage to the building.

Momentum

Momentum is the matter of motion. The momentum of an object is changed by force. Momentum is  mentioned in the third law of motion. 

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BIBLIOGRAPHY

Michael, Duncan. How Skyscrapers are Made.  New York: Facts on File Publications, 1987. Pp. 2-24. 

Bihler, Leonardo and Peters, Tom. "Skyscraper." The World Book Encyclopedia.  1999.

Holmes/ Corbs, Robert and Corbs/Blair, James. "Discovery Online" 

Buildings/Bridges/Tunnels. November 28,2001 <http://www.discovery. com/stories/technology/buildings/buildings.html

1885 First Skyscraper" November 28,2001 <http://cpl.lib.uic.edu/004chicago/timeline/skyscraper/.html

 World Book Young Scientist. Chicago: World Book Inc., 1990, -1991. pp. 42-43

Vignozzi, Alessandro. Buildings. New York: Barns & Noble, 1997. pp.28, 29

Impact." Illustrated Science Encyclopedia 1998

Weight" Encarta Encyclopedia December 12, 2001. Internet Explorer

Heimler, Charles Price, Jack. Physical Science. Columbus: Merrill, 1987. Pp. 66,67
 
 

 


ACKNOWLEDGEMENTS

I would like to thank the following people. Without their help, my project would not have been possible.

* My mom for picking me up at after school sessions, so I could work on my science project. For giving me ideas to write   about in my report and for being a big encouragement.
* My dad, for helping me build my building replicas, and for helping me conduct my experiment. He also was a big encouragement!
* My sister for taking pictures during my experiment and helping me with my project. 
* Mrs. Helms for helping me cut things for my board and for giving me ideas to improve my project.
* Mr. Newkirk for letting me stay after school to get caught up, correcting everything, and encouraged me to do my best.
 
 
 


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