EARTHQUAKE TOWER DESIGN
Engineering concept:
Design and fabricate a balsa wood tower to a given set of
specifications which can withstand a variety of simulated earth quake
seismic waves for a given frequency of time with a variety of loads. Work
with a predetermined budget to develop a cost effective design.
Building materials:
2/3 foot Balsa wood strips with 3 different cross sections. Strips
cannot be laminated together, ie: (edge to edge)
WOOD Glue ONLY!!!
Tower base
Tower roof
OPTIONAL - Load plates (large washers)
Roof loads (various masses)
Specifications:
Height: 30”, +/- 2”
Tower min/max perimeter at base: 4/6” square
Tower min/max perimeter at top: 4/4” square
No internal pieces. Tower should be clear from end to end.
No external “outriggers” or tip preventers.
Tower must be secured to shake table with brace and screws.
There needs to be 3 floors.
Glue can only be applied at joints where wood meets wood. No
lamination allowed. No webbing of glue. No pins or added supports
allowed. Only materials supplied. Do not bring in your own glue or
materials.
Procedure:
Divide into groups of 2/3. Do research. Brainstorm ideas. Draw full
size plan of one side. Build mockups with straws and paperclips or KNEX if
necessary. Measure and determine how much material of each cross section
is required.
Each team can pick up items a total of three times only. NO
EXCEPTIONS FOR EXCEEDING the number of times to pick up material.
If you go past the amount your TEAM WILL BE DQed.
This discourages over using and just building with no design. No
partial pieces may be picked up. Whole pieces only.
Teams begin construction. Best to build towers as flat sections on wax
paper over full size plan, then connect together.
Competition
Each team will be checked to verify that the tower meets the height
specification. (30” +/- 2” from the top of the base to the bottom of the top
piece), and that no materials other than the glue and wood provided was
used. Towers should be labeled with group members and period. Towers
will be impounded and kept by teacher until testing.
Any towers not meeting these specifications will be disqualified.
Tower will be attached to an earthquake simulator. Three levels of
vibration will be used for each test: 5, 10, 15 volts respectively at 15 seconds
for each level. Testing of each tower continues until the tower fails or passes
all load levels of testing.
TEST 1. The first test will be a simulation test with three levels of
vibration and NO LOAD.
TEST 2. After the final voltage vibration level, the simulator will be
turned off and a 2.5 LB load will be attached to the top of the tower. After
supporting the load for a minimum of 15 seconds, the simulator shall be
tuned on and stepped through the three levels of vibration as before (15
seconds for each level).
TEST 3. The simulator is then turned off and the procedure repeated
with a 5LB load.
TEST 4. The test continues with a 5 LB load attached as previously
described; however with 2.5lb. load at each level will be added and the
vibration is increased to 20 seconds.
Points are then awarded to each team based upon the highest
combination of weight and vibration levels which it successfully passed.
(The level immediately preceding the level at which it fails.)
Each teams score is then divided by the cost of the materials used to
obtain the tower’s Figure of Merit. The team with the highest Figure of
Merit shall be declared the winner. Points based on the following:
Points scored are those points gained by the tower under test prior to
failure. 25 points for full size drawing.