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
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