Transcript Earthquake Tower Competition Presentation

• Forces within the Earth are constantly bending
and straining the thin crust we call home.
• Most earthquakes occur within the earth’s
upper crust, 15 miles below us.
• Major earthquakes that occur in heavilypopulated areas with tall buildings can result
in tremendous destruction, injuries, and
death!
A Large Boat on a House?
• Seismic waves cause tremors (shaking).
• Primary waves move fast with a push-pull action.
They show up on a seismograph as a smooth line.
• Secondary waves are slower but cause the most
damage to structures. They show up as jagged up
and down lines.
• The “focus” is the point in the Earth where the
earthquake started.
• The “epicenter” is the point on the Earth’s surface
directly above the focus. Damage is usually
greatest at the epicenter.
• Most earthquakes leave a crack called a “fault
line”.
Magnitude
• In 1935 American Seismologist Charles Richter
came up with a 1-10 scale to measure an
earthquake’s “magnitude”.
• Each single number increase in magnitude,
like 6.0 to a 7.0, is 10 TIMES more powerful
than the lower number.
Worst Earthquake in History
• January 23, 1956, Shensi, China
8.0 on the Richter Scale
830,000 deaths
Worst Earthquake in America
• 1906, San Francisco
• 7.9 on the Richter Scale
• 3,000 deaths
Worst Earthquake in Idaho
• October 28, 1983, near Challis
• 6.9 on the Richter Scale
• 2 deaths
Question
Why such a difference in deaths?
• China: 800,000 (8.0)
• San Francisco: 3,000 (7.9)
• Idaho: 2 (6.9)
Structures must survive:
• Compression
• Tension
• Shearing
• Torsion
• Bending
• Every building has its own “resonance”, where the shaking of
the ground matches the shaking of the building.
• Resonance results in maximum damage.
• In this chart, a 10 story building that shakes back and forth
once every one second will likely be shaken apart.
FACT: Most
earthquakes shake
between .5 and 2
seconds per cycle,
making 5-20 story
buildings the most
vulnerable!
Building Heights & Natural Frequency
Building Height
Typical Natural Period
2 story
.2 seconds
5 story
.5 seconds
10 story
1.0 second
20 story
2.0 second
30 story
3.0 second
50 story
5.0 seconds
Speakers
Boy
Required:
• Earthquake Tester
• Tower block base
• Foundation block
• 1/8” welding rod
• 4 Pitsco dragster wheels
• Engineers, architects, and scientists are
working together to learn how to design and
build earthquake-resistant buildings.
• Most deaths have been caused by faulty
construction or poor building site.
• Poor countries with no or limited building
codes, tend to see much more damage than
countries like America.
Brick vs. Framed
• Brick buildings tend to crumble quickly in an
earthquake compared to those built with
wood or steel frames.
• The best defense against a strong earthquake
is to build a structure that will move WITH the
earthquake and absorb most of the
destructive energy.
• Steel and concrete-reinforced steel are the
best solutions for large buildings.
• To design and build a scale 20 story building (if
full size would measure 40’ x 40’ at its base)
that will be able to withstand an earthquake
without damage.
• Such a building would weigh 1.5 million TONS,
so your building will include weighted floor
plates that will be equal to that weight, to
scale.
EXAMPLE
•
•
•
•
•
•
•
•
•
•
•
Green structure glue, white glue, or hot glue
20’ of 1/8” x 1/8” balsa wood
Graph paper
Pins or tape
Cardboard or wood board
Cutting board
Hobby knife
Foundation block
Tower base
Wooden floor plates
Waxed paper
1. Draw one side of your building actual size on
graph paper.
2. Plan how to best use your 20’ of balsa!
3. Your skyscraper MUST be at least 20” tall.
4. Lay waxed paper over your drawing.
5. Lay pieces of balsa wood over your drawing,
mark with a pencil, and cut to length.
6. Glue balsa together but NOT to the waxed
paper.
6. Once dry, position your first wall vertical.
7. Glue the bottom of your first wall to the
foundation block.
Wooden Floor Plates
8. It is suggested that you glue wooden floor
plates to the first building side every 10cm (4”)
from the BOTTOM of the foundation block.
4”
9. Build a second side and glue it opposite the
first side.
10. Add additional sides or bracing until you’ve
used all of your balsa (or less, if desired).
Requirements
•
•
•
•
20” tall
Foundation glued to base.
No more than 20’ of balsa wood.
Each floor must have enough headroom for a
2” tall army man to stand freely without
touching anything but where he is standing.
• Glue should not be visible.
• No wax paper
1. The earthquake tester allows us to record an earthquake sequence.
2. An earthquake sequence will be pre-recorded for your shaking
pleasure.
3. The first team will insert a bolt, nut, and washers to each floor
above the foundation block.
4. The first team will then place six (6) army men, one on each floor,
without touching anything but the floor plates.
5. The tower will be tested until any floor fails.
6. You may stop the quake anytime after 10CPS.
7. The highest setting the building endured will be recorded.
8. The number of army men that remain on its original floor will be
recorded and you receive 5pts for each.
9. You will receive an extra two feet of balsa wood after each test.
10. Other towers will experience the exact same earthquake
sequence.
CONSTRUCTION QUALITY (Amount of glue, correct dimensions, square, plumb)
30/40/50 points.
•
•
•
•
DAY 1: One washer per floor (5 ounces total)
5 cycles per second (CPS) before failure = 5pts.
10 CPS before failure = 10pts.
20 CPS before failure = 20pts. (70pts. possible at this point + 5pts for each army man
still on a floor.
Day 1 Total Points: _____ + Construction Quality = ______
Day 2: Five washers per floor (25 ounces total)
5 CPS before failure = 5pts.
10 CPS before failure = 10pts.
20 CPS before failure = 15pts. (85pts. possible at this point + 5 pts for each army man
still on a floor. Day 2 Total Points: _____ + Day 1 Total Points = ______
Day 3: Ten washers per floor (50 ounces total)
5 CPS before failure = 5pts.
10 CPS before failure = 10pts. (100 points possible)
20 CPS before failure = 20 pts. (110pts possible + 5 pts for each army man still on a
floor.
Day 3 total points + Day 2 total points = __________.
_________ TOTAL / 100 POINTS