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Week 4 WORKSHOP During the workshop time, our group needed to built a 1m ‘bridge’ with 3 same dimension woods and one

plywood. As for thinking and testing by hand about different characteristics of wood and plywood, we found that the plywood pretty much softer than the wood which is easily to be deformed. As for the wood, it is the material which can return to its original shape easily under stress, which means that the

elasticity of wood is better than the plywood.

As for the main structure of our ‘bridge’, we make the wood vertical standing with the

This side view sketch is to illustrate the

plywood underneath, as we thought the plywood

connection, which we use the common

is not easy to break under stress as the

nails for general construction. Each wood

deformation is better.

bricks has two nails connected to the wood same as the back side of plywood.

During the test, the basic data of the

compression on the ‘bridge’ is 9KG, as the increase of the pressure, the first breakage is under the strength of 280KG. The place

These two photos

of the first fracture take place on the wood

show the deformation

(as shown on the picture). As what we

of our bridge under

guessed, the plywood is really soft material

compression from 38

for deforming , which is not easy to be

to 40.

broken even under high strength of compression.

After the testing, it reminds me one things that said on the textbook. Grain direction is the major determining factor using the wood as the structural material. As the data provided in the textbook, “the allowable

compressive force perpendicular to its grain is only about 1/5 to 1/2 of allowable compressive force parallel to the grain” (Ching, 2008,p12.11). It can easily found in the left picture, the compression on the wood is perpendicular to the grain of the wood, thus, it make me think that the strength can increase of the grain is parallel to the strength.

Reference: Ching, F 2008, Building Construction Illustrated, n.p.: Hoboken, N.J. : John Wiley & Sons, c2008

Week 4