CONSTRUCTING ENVIRONMENTS REFLECTIVE JOURNAL- WEEK 2 This week’s focus was on the referencing of structural systems from natural and manmade systems such as gravity, wind, water and seismic which are lateral forces. A couple of new words unraveled as the lecture proceeded and I found myself to be intrigued by the use of bio-mimicry and bio inspiration which is using nature either as a mimicry or an inspiration, in their literal sense. The example of the skeletal structure of a whale was used to construct the frame of an airplane and a house amidst a jungle was made in shape of a football. The cellular structure of a plant was also used in inspiring the structure of the buildings. The materials, functions, contexts, sustainability are factors brought into light with the construction and structure of the igloo and the teepee which I found particularly interesting. Their structures do vary because igloos use the concept of lattice work where as teepees use cladding. This week’s tutorial was to test the fundamentals of frame. It consisted of a task in which we were provided balsa wood and it had to be cut into forty strips of any length and we had to construct a tower as tall as possible. My group members and I initially sought out to making the base of the tower and as we placed the strips of wood diagonally to form a triangle at the top point by connecting legs to the base of the structure.
Apex of structure
Vertical line through which a line passes through acting as the center of gravity
Base of structure
The diagrammatic representation of the structure is somewhat in the shape of a pyramid where the wooden legs/beams converge at the apex through which the center of gravity acts. Since the balsa wood was cut into thin strips, the material was not strong enough and we had to add extra support to the frame of the structure by adding bridges at the edges to make the structure stabilized from collapsing as seen below in the diagram:
The final outcome of our structure was:
There were various factors contributing to the dis-orientation of our tower: 1. 2. 3. 4. 5.
Thickness of the wooden strips Time taken for the glue to dry/ not a strong glue Limited number of sticks Inaccuracy in measuring the distance between one wooden beam from the other Limited time
By triangulating the structure, it is subject to axial tension and compression. Instead of continuing with this structure, we could have had a square base so that the load would be less concentrated but distributed well across the structure. 1This is the concept of plate structures- they function as monolithic structures that disperse applied loads in a multidirectional pattern. This way it behaves as a two way structure which also increases the number of members into which the shear is transferred and reduces the forces in the members. By following this method, the structure would be more stable and have less chance of swaying and finally collapsing if any load is transferred to it. If triangulating it would be a better option, then the measurements have to be taken into consideration such as the distance between one wooden leg to the other or the angle of slant but this would be relatively difficult taking into the consideration the constraints of this task as mentioned in the previous pointers. Below are structures my classmates constructed:
1
D.K Ching, F. 2008, "Plate structures" in Building Construction Illustrated, Fourth edn, Wiley, , pp. 2.18.
The structure above on the left is stable because of the spacing between the wooden legs is fairly accurate but then again the structure as a whole is very short contributing to its stability. The group could have made a large triangular base and continued to the apex, narrowing every triangle the bottom legs joined to as the structure gets taller. The structure above on the right is unstable because it is disorientated although it has a great height compared to the other two structures previously discussed about. The problem with this structure was that the spacing in terms of height was too far apart having a concentrated load on the base causing all the tension to be passed down to the legs causing them to slightly bend outwardly. The structure could have been improved by providing extra support by attaching additional strips of wood diagonally across the rectangles as well as include bridges. So far, I am enjoying my construction lectures and tutorials and hope to learn more from the upcoming sessions. I am looking forward to the site visit this Friday!