The Effect of
Wind Load on a Building

photo of researcherResearched by Ben M
2005-06




PURPOSE

The purpose of this experiment was to determine the effect of height to width ratio on the wind load of a building.

I became interested in this idea when I was watching a news report about a hurricane that made some taller buildings fall down while sparing many shorter buildings. People paid lots of money and did extra work to fix them.

The information gained from this experiment could help architects determine how to design buildings of a certain size so the wind has less drag on it. People could get hurt if the wind has too much drag and makes the building fall down.


HYPOTHESIS

My hypothesis was that as the height to width ratio increased, the wind load (drag) would increase.

I based my hypothesis on an article from World Book Encyclopedia that was called “Wind Surface.” It said, “That wind can blow so lightly that you can’t even feel it or it can blow so hard that it rips trees out of the ground and can crush buildings.”   

 
EXPERIMENT DESIGN

The constants in this study were:
•    The speed of the wind.
•    The size of the wind tunnel.
•    The time I gave the wind to blow on the structure.
•    The type of material I used to make the structure (plywood).
•    The surface area of the shape facing the wind.
•    The shape facing the wind.
•    The unit I used to measure with.
•    The strength of the wind.
•    The size of the wheels.
•    The material the wheels are made of.
•    The number of wheels on each structure.
•    The size of the axels.
•    The number of axels.
•    The material the axels are made of.
•    The size of the axel holes in the wheels.
•    The place where the wind comes out of.
•    The machine the wind comes out of.
•    The size of holes the axels go in the structure.
•    The type of glue I used to glue the structure together.
•    The placing of the structure in the wind tunnel.

The manipulated variable was the height to width ratio of the structures.

The responding variable was the force of drag.

To measure the responding variable, I used a spring scale. 


MATERIALS

QUANTITY ITEM DESCRIPTION
1 Stopwatch
1 73cm by 73cm Wind Tunnel
16 Wheels
2 Leaf Blowers
16 Axel pegs
1 piece of 30cm by 121cm Plywood Board
1 Electric Wood Saw
1 Bottle Wood Glue
1 Can Spray Paint
1 Box Small Nails
1 Clamp
1 Carpenters Pencil
1 Ruler
1 Hammer



PROCEDURES

I)    Build Structures 
A.    Buy a plywood board that is 30in by 121in.
B.    Cut four pieces of board so they are 5 inches by 4 inches then glue and nail the boards together so that one of the faces of the board has an area of 20 inches2.
C.    Put your 16 wheels on the 16 axle pegs.
D.    Drill a hole in the board that is big enough for the axle peg to go in but small enough so that the peg doesn’t come out easily. Put wood glue around the axle peg’s end so that it will stay inside the hole.
E.    Clamp down on two sides with your clamp.
F.    Screw a metal hook into the front of the structure.
G.    Cut twelve more pieces of wood that have four 4 by 5, four 2 by10, and four10 by 2. Repeat step one with all.
II)    Move wind tunnel if needed.
A.    If you need to take wind tunnel into a quiet room with no people in it but you and a supervisor.
III)    Start your experiment.
B.    Put your structures in the wind tunnel one at a time and let the wind blow on them for two minuets every ten seconds write down how many newtons are pushing on the structure.
C.    After you do this for six times with every structure go to each amount of time being a multiple of thirty except zero and find the average newtons of each structure in the multiples of thirty going to one-hundred-twenty.


RESULTS

The original purpose of this experiment was to determine the effect of height to width ratio on the wind load of a building.

The results of the experiment when my structure had a surface of about 20 inches2 having wind blow on my structures for 10 minuets and me recording how many newtons were pulling on the spring scale on my first structure at
(See the table and graph below.)

 
CONCLUSION

My hypothesis was that as the height to width ratio increased, the wind load (drag) would increase.

The results indicate that this hypothesis should be rejected because my results were mixed. My hypothesis said that when the height to width ratio increased so would the wind drag. On my first two structures that was correct. On my last two however it was the exact opposite of that. On my last two structures it was the smaller the height to width ratio the more drag the building had on the wind. 

After thinking about the results of this experiment, I wonder if it matters with other objects such as a car or a plane.

If I were to conduct this project again I would do the experiment with more trials than I had this.

RESEARCH REPORT


Introduction
Wind is air moving across the earth’s surface that is caused by the uneven heating from the sun on the earth’s atmosphere.
A skyscraper’s a structure that is made from glass, stone, concrete, metal, or wood. It can also be made from other materials. Before the skyscraper is actually made the architects must create a blueprint of the building so that, builders know exactly how to make the building.
The construction workers first make a central core to guide and support the building. If this wasn’t done the partially completed building could fall as soon as the wind started to blow. The core is made out of steel and concrete mixed together to make a foundation. The next step is to make a frame. That is made of thick iron and steel bars that have to be attached so that a wall, floor, and a ceiling can be made and put onto the frame. The walls, floors, and the ceilings are made of concrete and steel mixed together so that it is hard to puncture and break through the walls, floors, and ceilings.


Storms
A hurricane is a storm that happens when clouds over a tropical ocean are blown in a spiral. The middle is called the eye of the storm. It has no rain or clouds and the eye can be 10-14 miles in diameter. The part at the edge of the eye is called the eye wall. It is made up of clouds that blow with the wind at a high 200 miles per hour.
 
Wind Effects
Wind erosion is caused by wind blowing across the land while taking dirt and small rocks with it. The wind leaves behind bigger and heavier rocks because they’re too heavy for the wind to pick up. There’s wind erosion called desert pavement. The desert pavement is when the wind is so strong that it lifts everything off the rock layer leaving it like it has been paved. Sand dunes are a wind effect too. Loose sand blowing until it has made a hill that is still loose and constantly shifting make the sand dune.
Wind shear is the change of speed and direction in the wind. Wind shear can cause a plane to crash when it’s taking off or just landing at an airport. Wind shear will cause a plane to bob up and down if the plane is in the air.

Seasons
In the winter the wind can be so cold that it can freeze moisture instantly. If a plant has water on it and the air is less than 32 degrees Fahrenheit with the ground colder than the plant the water will freeze and turn into hoar frost.

Building Safety
A building design team’s most important job is to make sure that the people dwelling in the building are safe from earthquakes and strong winds. Since a building’s core is usually stiff, an earthquake could knock the building down or damage the building. You can get the building specially made so that under the building is a rubber pad.  When the ground shakes the pad absorbs the shock so that the building won’t fall down. The other thing that the architects have to do when they draw the blue print is make sure the foundation is strong enough to stand strong winds because the wind can go up to 200mph and higher.

Beams and Bolts
A building’s design is to be light enough and strong in durability. If the building isn’t light in weight the beams will push too hard on the columns causing the building to fall down. The bolts that hold the beams together need to be as strong as the beams otherwise the building will collapse. If you don’t use bolts to hold the beams together you can weld the beams together but it isn’t as strong

Summary
Wind is air moving across the earth’s surface that is caused by the sun’s uneven heating of the earth’s atmosphere. A sky scrapper is a tall building made by metal, glass, and sometimes concrete. Wind can damage tall structures, so architects must try to create the best design.
 

BIBLIOGRAPHY


Barnes, Gary “Hurricanes” World Book Online. December7, 2005       http://www.worldbookonline.com 

Cosgrove, Brian Eye Witness Weather. New York Doring Kindsly, 2000 pp.6-63

Dalgliesh W.A. and Boyed D.W. “Wind on buildings” Canadian Building Digest November30, 2005 http://irc.nrc-cnrc.gc.ca/pubs/cbdlcbd028.e.ftml
 
Ghandakly, Adel G. “Wind Power” World Book Online. October27, 2005 http://www.worldbookonline.com

Lemone, Margaret “Wind.” World Book Encyclopedia. 1998

Oxlade, Chris Super structures Austin: Rain tree steck, 1997 1-45

“Wind Shear” Weather Street. November9, 2005
 http://www.weatherstreet.com
 
“Wind Shear” World book online. November9, 2005 http://www.worldbookonline.com
 


 ACKNOWLEDGEMENTS

I would like to thank the following people for helping make my project possible:
•    My parents for taking me so that I could do my experiment.
•    My teacher for letting me borrow his wind tunnel for my experiment.
•    My dad for helping me make my structures.
•    My brother for helping me cut the wood for my structures.
•    My sister for helping me cut and paste my papers and pictures on my display.


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