CONSTRUCTING ENVIRONMENTS LOGBOOK EMILY KESKINEN 702249 SEM 1 14’ ENVS10003
WEEK 1 ENVS10003
A circular design was chosen for our MDF (medium density fiberboard) construction. This was chosen because by using a circular base a dome roof, that would enclose the building, would be easier to create. The arch had to be made as we built the structure. The aim of the activity was to build the structure as high as we could and ensure it was able to carry a heavy load.
When a live load (a temporary load that is added to a structure, (ENVS10003, 2014b)) is applied to a structure the load takes the most direct route to the ground. This is indicated in the load path diagram below. In terms of a masonry construction such as the MDF building the load gets transferred evenly down through each individual piece. Due to Newton’s Third Law the load that travels through the structure is met with a reaction force that is equal and opposite in direction coming from the ground.
The image on the previous page demonstrates the use of the masonry technique that was used to create our structure. The gaps between the MDF pieces were due to the circular base of the building. - The masonry structure creates an even load between all MDF pieces. This ensures that there are no weak sections in the building. - MDF is an isotropic material that performs similarly under both tensional and compressional forces. It also has a volumetric shape (ENVS10003, 2014a).
Due to the compression forces that the MDF pieces apply to each other we were able to build in the arch as we built the rest of the structure. This allowed parts of the MDF to be unsupported as can be seen in the images below. Compression is a main aspect of a solid structure and this makes it easier to have arches in the structure (ENVS10003, 2014c). A compression force occurs when external objects apply a force on the material and cause it to squash together (Environments, 2014).
Once the arch had been built in we needed to build the tower as tall as we could. This had to be achieved while also ensuring we were able to close off the roof. This is where the circular design was useful as we could build the MDF blocks closer together on each layer and they would all eventually join together.
Dome roofs perform well under compressional forces, as this is how they are designed. They are generally supported with a tensional ring to prevent the roof from bursting out (Ching, 2008). As this is a small-scale design with small forces no such ring was needed and the masonry method was sufficient to create the structure.
After layering the MDF blocks higher they eventually created an enclosed roof for the building. To follow on the with task MDF pieces were added four at a time in an alternating pattern to increase the height of the building while still being able to withstand the applied load.
The applied load of the box of MDF pieces provides an extra compressive force on the structure. As can be seen in the image to the right our structure was strong enough to withstand this force. The circular construction using a masonry method of construction meant the weight of the box was evenly distributed throughout the structure.
The next part of the task was to slowly pull apart the structure and determine its failing point. To do this we removed pieces of MDF pieces at the base of the structure.
Due to the compression forces acting on the structure we were able to remove MDF pieces from the structure. The masonry construction combined method means that the loads can be transferred through to other MDF blocks in the structure to compensate for the removal of MDF blocks. If the structure was built with MDF blocks stacked on top of each other, when one block was removed others would fall around it and it would be unstable. Hence the masonry structure is effective for creative a stable structure.
One of the other groups opted to build a square base for their structure while still using the masonry method. Using the square base made it more difficult for them to close off the roof of the structure. Another group used a circular base and began to build their tower as tall as they could. Due to time constraints they were unable to finish.
REFERENCES – WEEK 1 Ching, F. D. K. (2008). Building Construction Illustrated (Fourth ed.). Hoboken, N.J.: John Wiley & Sons, Inc. Environments, C. (2014). ENVS10003: Constructing Environments -‐ Basic Structural Forces (I). Retrieved 15/03/14, from https://app.lms.unimelb.edu.au/bbcswebdav/courses/ENVS10003_2014_SM1/WEEK%2001/Basic%20Structural%20Forces%201.pdf ENVS10003 (Producer). (2014a, 15/03/14). W01 m1 Introduction to Materials. Retrieved from http://www.youtube.com/watch?v=s4CJ8o_lJbg&feature=youtu.be ENVS10003 (Producer). (2014b, 15/03/14). W01 s1 Load Path Diagrams. Retrieved from http://www.youtube.com/watch?v=y__V15j3IX4&feature=youtu.be ENVS10003 (Producer). (2014c, 17/03/14). W02 s1 Structural Systems. Retrieved from http://www.youtube.com/watch?v=l-‐-‐ JtPpI8uw&feature=youtu.be
BALSA WOOD CONSTRUCTION
The week two studio task was to design a tower to the roof using one piece of balsa wood. The balsa wood is an anisotropic material that performs more efficiently under tension than compression (ENVS10003, 2014a). We chose to use a triangular base for our tower, as it would keep the center of gravity in the middle and make it more stable. As can be seen by the original design pictures the structure used a skeletal system otherwise know as a frame system. These systems are very common and can efficiently transfer loads through to structure (ENVS10003, 2014c).
The braces that were used in our structure were designed to provide stability and to reduce the movement of the tower. The braces reduced in size and covered a smaller span between the columns. The braces were joined using overlapping ends to provide more support to them. The braces would also help to transfer loads between the columns allowing for added stability.
When we attached the second brace to the tower we did not ensure that the points of the triangles lined up. Due to this error the columns were twisted. This twisting resulted in the structure being unstable. To amend this problem we needed to reattach the columns to the triangle so they were inline.
We had originally intended on building the building continuously however we realised the building would become too tall for us to continue building. As a result we decided to build the tower in two sections and then join the two halves together.
As the tower got higher we noticed it was becoming less stable. This was partially due to weak joints between the columns and the braces. To add stability to the structure we added diagonal braces to each join. This reinforced the joins and made them stronger.
As well as the joints being unstable the columns were beginning to collapse under the compressional forces. As the balsa wood columns were slender they were susceptible to buckling under the forces (Ching, 2008). To prevent the lateral movement of the columns outwards an extra brace was added to the structure that wrapped around the outside of the three columns. This brace stopped the columns from being forced outwards and provided added stability to the tower.
After completing both sections of the tower we joined them together to create our tower. We did this by placing the base of the second half on the to brace of the first half. This altered the original design of our tower. With the tower being ultimately two sections we believed this would create a more stable structure as the weight was more centered.
It was originally planned that we would use superglue to attach the top half to the bottom half. This connection wasn’t strong enough and needed to be reinforced which is why we wrapped sticky tape around the joins. To ensure the joins would not rip apart.
Another change to our design that occurred during the construction process was to remove the triangle brace from the top of the tower. Instead of having a brace we taped the ends of the three columns around one column that would extend up.
We did this as it was going to be easier to obtain the height we needed for the task however it did compromise the structure of the building. As is shown in the images the lack of structural support resulted in the top of the tower tilting to the side. Although the bottom section remained stable due to the extra braces.
External loads were applied to the structure causing compressional forces on the tower. Due to these forces the columns began to buckle. This resulted in the realisation of an inconsistency when building the tower. Some of the columns were orientated at different angles. Some columns were twisting under the load whilst others were bending outwards. This twisting contributed to some of the instability of the tower. The sketch on the right shows the load path diagram of the structure. It demonstrates how the load is shared evenly among the columns and beams. Some other groups opted to build their towers using square bases. These towers were less stable and underwent lateral movement. They also used more balsa wood. It was also discovered that if the base were to wide or too small it would influence the overall stability of the building.
REFERENCES – WEEK 2 Ching, F. D. K. (2008). Building Construction Illustrated (Fourth ed.). Hoboken, N.J.: John Wiley & Sons, Inc. ENVS10003 (Producer). (2014a, 15/03/14). W01 m1 Introduction to Materials. Retrieved from http://www.youtube.com/watch?v=s4CJ8o_lJbg&feature=youtu.be ENVS10003 (Producer). (2014c, 17/03/14). W02 s1 Structural Systems. Retrieved from http://www.youtube.com/watch?v=l-‐-‐JtPpI8uw&feature=youtu.be
GLOSSARY Load path – represents the direction of the load as it travels through the structure. (ENVS10003, 2014b) Masonry – describes the way in which a structure has been built using individual pieces joined together with a grout. E.g. brick and mortar. Compression – occurs when an external force puts pressure on the object and compacts it to make it shorter. (Environments, 2014) Reaction force – the force exerted on the structure (usually from the ground) that is equal and opposite in direction to force the structure exerts on the ground. Point load – a load that is specific to a localised area in a structure. Beam – carries/transfers loads across a span to the axial support columns. (Ching, 2008) Structural joint – connect individual pieces of material together to help form a structure. Stability – the ability of a structure to maintain a stable balance when external lateral forces and vertical loads are exerted on the structure. (Ching, 2008) Tension – occurs when an external force is applied to a structure that elongates the object. (Environments, 2014) Frame – comprised of columns and beams to create a wall or a section of a structure. Bracing – adds support to a structure by inhibiting lateral movement either by diagonal bracing or sheet bracing. Column – a structural piece that performs well under compression to provide axial support to a building. (Ching, 2008)
REFERENCE LIST Ching, F. D. K. (2008). Building Construction Illustrated (Fourth ed.). Hoboken, N.J.: John Wiley & Sons, Inc. Environments, C. (2014). ENVS10003: Constructing Environments -‐ Basic Structural Forces (I). Retrieved 15/03/14, from https://app.lms.unimelb.edu.au/bbcswebdav/courses/ENVS10003_2014_SM1/WEEK%2001/Basic%20Structural%20Forces%201.pdf ENVS10003 (Producer). (2014a, 15/03/14). W01 m1 Introduction to Materials. Retrieved from http://www.youtube.com/watch?v=s4CJ8o_lJbg&feature=youtu.be ENVS10003 (Producer). (2014b, 15/03/14). W01 s1 Load Path Diagrams. Retrieved from http://www.youtube.com/watch?v=y__V15j3IX4&feature=youtu.be ENVS10003 (Producer). (2014c, 17/03/14). W02 s1 Structural Systems. Retrieved from http://www.youtube.com/watch?v=l-‐-‐ JtPpI8uw&feature=youtu.be