Week 3 Journal Wenjie Cai
In week 3 studio, we were doing works as groups of three to build a beam and make as strong as we can to suffer load. I am in Group 3 and the materials that provided to us are one ply (1200 x 3.2 x 90 mm), three pines (1200 x 35 x 35mm) and several tools (figure 1).
figure 1: Materials for building beam (author) During our planning, we think that our pines are strong enough to support heavy load. Therefore, our first step of building our beam was to nail two pines on the same surface of the ply with 6 nails to make it as a simple frame (figure 2 & 3). Before we nailed them together, we cut the ply to make it shorter so that we could use fewer nails to make the fixed.
figure 2: first step of constructing 2 WEEK 3 JOURNAL
(author)
figure 3: Structure of the frame (author) In this type of structure, using two pines is better as they can share the heavy loads and separate the stress into the both side of the ply instead of concentrating them in the middle. This structure strengthens the ability of the beam to carry load. At the second stage of constructing, we use the extra ply that was cut in the first step to strengthen the beam. We cut it into several little equal pieces and so did the other pine that was not used (figure 4).
figure 4: example of cutting the materials (author) We filled some of the little pieces of pine in the gap between two long pines of the beam (figure 5). We also used the little pieces of ply to cover the pines and nailed the ply with the beam with two nails for each (figure 6).
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figure 5: little piece of pine in the gap (author)
figure 6: usage of the little pieces of ply (author) As I mentioned, the purpose of this structure is to strengthen the beam. These little pieces of pine were used to support the long ply so that it would not be broken easily. The little pieces of ply were used to make the little pieces of pine fixed so that they can play their important role. If we did not use the little pieces of ply, the pines would easily fall and could not support the beam. These materials also used to connect every part of the beam so that they have stronger connection and share the loads equally. After finishing this step, the whole construction of the beam was completed (figure 7).
figure 7: Complete beam 4 WEEK 3 JOURNAL
(author) During testing the beam’s strength, we decided to put it at a position that the surface the ply faced up. However, we realize that the ply may be easily broken because the pines are not flexible and the ply is too thin. When the heavy loads push on them, the strong depression may break the beam (figure 9). Pines may be stronger to suffer the loads and the ply was flexible enough to support the two pines so we put the beam in opposite position (figure 8).
figure 8: different positions of putting the beam (author)
figure 9: Possibilities of different positions
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(author) The same as our estimates, the pines were very strong and the ply was flexible enough. The beam was very strong that it was hard to be broken. When is was nearly reach the bottom, we heard sound of cracking. When we looked at it carefully, we could only see it cracked a little bit in one of the pines (the red circle in figure 10).
figure 10: Cracking of the pine (author) We also test it in another position as figure 11 shown. The results of it was that one of the nails, which was used to nail the little pieces of ply, was broken and the pines were broken (figure 12).
figure 11: Second test of the beam (author)
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figure 12: Breaking pines (author) From figure 12, we can see that the upper one was broken more serious than the lower one as it suffer more loads. While we were building this beam, we did not put the little pieces of pine into the middle of the beam. Therefore, when the forces acted on the upper pine, there was nothing to support it. It was broken easily without support and then cause the lower one to break. If we put one more little piece of pine in the middle of the beam, the upper pine would be supported and these two pines would share the forces so they would not be broken so easily (figure 13).
figure 13: Beam with support by little pieces of pine (author) In conclusion, in this week’s studio, I learn that materials are very important for building a beam. Strong materials such as the pines (1200 x 35 x 35 mm) make the whole structure stronger. Also, sharing forces between every part of the beam is very important as well. Only one of its parts is impossible to support the loads on the whole beam. Every piece of materials is important in sharing load.
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CONSTRUCTING ENVIRONMENTS ENVS10003 ACTIVITY_CONSTRUCTION WORKSHOP NAME GROUP MEMBERS 1_DESCRIPTION (length, width, depth, composition and structural properties) AND PHOTO OF ALL MATERIALS PROVIDED
Length 1200mm, width 35mm, depth 35mm pine x 3 Length 1200mm, width 90mm, depth 3.2mm ply x 1
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2_PHOTO AND DESCRIPTION OF ALL TOOLS USED 2 hammers, 1 try-square, 1 saw, several nails,
3_SKETCH OF YOUR DESIGN AND PHOTOS OF ALL FOUR DESIGNS Our Group’s:
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Other 4 groups’:
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4_PHOTO AND DESCRIPTION OF STRUCTURAL PERFORMANCE AND FAILURE MECHANISM OF ALL FOUR DESIGNS
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1. One 1200mm x 42mm x 18mm pine in the middle, four 600mm x 90mm x 3.2mm ply nailed on both side of the middle pine. Several little pieces of pine are nailed beside the middle pine, which is the gap between the other thin plies.
It was being put in a vertical position. Easily
be broken because of the weakness of the plies. Too many nails become a problem for this design. Nails make the structure weaker. 2. Two 1200mm x 90mm x 3.2mm plies were nailed together. A 1200mm x 42mm x 18mm pine nailed on one side of the nailed-plies. Two short pines with 42mm width & 18mm depth were nailed either on the top or the bottom of the middle of the beam. Very flexible materials and stronger support in the middle. Therefore, it was not broken even if it reached the bottom. 3. Two 1200mm x 42mm x 18mm pine were nailed on one surface of the 1200mm x 90mm x 3.2 mm ply. Four little pieces of pine were filled in the gap between the two long pines to support them. It was put in vertical position that is similar with the first design and it also had the same problem with the first design – the ply was too weak in this position. Therefore, it was broken easily. 4. It was designed as a truss. The 1200mm x 90mm x 3.2mm plies were used as the top and the bottom of the truss. The cut-pines were used in the middle to form several triangle structures. The pines have transferred the load so that the load was not concentrate only in the middle of the beam. It was broken because of the break of the nail. The middle-structure was separated with the bottom.
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5. Our groups design used two 1200mm x 35mm x 35mm pines to nail with the 1000mm x 90mm x 3.2mm ply. Four little pieces of pines were used to fill in the gap between the two long pines. Four little pieces of plies were used to cover and support the pines in the gap and strengthen the connection of the two long pines.
5_DESCRIPTION/DEFINITION OF THE FOLLOWING KEY CONCEPTS Span_ The distance between two vertical support of a horizontal structure. Cross Section_ Something that is cut straight through a material Strength_ The ability of a material/structure/construction of carrying loads. Compression_ A force that compress on something Tension_ A force that pull the material apart Flexion_ The action of being bent but not be broken. Shear_ It happens when two touched surfaces shift in opposite direction Deflection_ Buckling_ A material attached to a strap.
6_EXTRA NOTES AND COMMENTS
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