Week 2 Lecture: Possible structure 2: The lecture in week 2 was full of creativity and different design skills, we were told to make a ‘water tank’ model building which must be able to support the load above this. Materials required for the practical: Several plastic tubes Several pins Plastic water tank
Theoretically it can be considered as a strong structure, because the weight of the load will be transformed to the tension of the tube. It can be illustrated as the diagram below:
Main difficulties and solutions: The main obstacles are the stability of different structural designs; the plastic tubes were too soft to afford the weight of the load. However, we can increase the load capacity by using more tubes which crossed with each together; it may give us a more stable structure like the following picture. Possible structure 1:
The difference between this structure and the precious one is the number of legs. Theoretically, it will become stable when the downward force is separated into different legs. However, as the matter of fact, the contact areas were extremely small and uneven, so this type of structure cannot support the loads. Possible structure 3:
When the load is acting force on this structure, it means pushing the structure downwards; therefore the height can be slightly reduced. In this case, the component forces are tend to be the tension force of the tube as I expect tension is strong than compression in this structure.
It was the structure using 2 pins per column
rather than only 1 in the previous examples. This design uses special triangle posts and braces between them, it made the structure have a larger footing and shorter post lengths, so that it was theoretically stable.
planar structure e.g Opera House
Knowledge map of E-Learning: Structure system: Solid system is mainly consisting of stones, bricks and mud structures. E.g Arch, the Great Wall in China
(As we see the picture above, it can be observed that the materials of this structure are the combination of bricks and muds, so this type of system was commonly used in ancient buildings.) Surface structure is a type shell and
(Opera House uses the advanced shell design, it is now considered as an outstanding building technology.)
Frame System (skeletal structure) is a good way to transfer loads down through the foundation, it the most commonly used structure among the buildings.
(Frame structure consists of beam, column
and roof, this structure is very popular in modern building design.) Membrane system is able to cover larger area efficiently and cheaply. Hybrid system is less common, some hybrid structure uses membrane called ETFE (Ethylene
tetrafluoroethylene, ETFE, a fluorine based plastic, was designed to have high corrosion resistance and strength over a wide temperature range.) Both systems can be used more efficiently and economically. e.g Swimming Cube in Beijing Olympics
(The surface of the swimming cube is a structure of membrane system, it is designed to maintain the inside temperature and prevent the sunlight coming through)
Environmentally Sustainable Design (ESD) considerations: Key terms: Embodied energy is the total energy during all stages of material’s life. Life cycle begins with extraction of raw material from the earth and ends with the disposal of waste of product back to earth or recycled into other products. Recyclability is potential for a product to be reused and transformed into a new product. Carbon footprint is a measure of the amount of greenhouse house gases generated during the fabrication, transportation and use of a particular product. Stages: 1. Raw materials acquisition 2. Primary processing and refining 3. Manufacturing 4. Delivering 5. Construction use and maintenance 6. Final disposal
Common ESD strategies: Local materials Material efficiency Thermal mass Night air purging Solar energy Wind energy Cross ventilation Smart sun design Insulation Water harvesting
directions or planar.
Three different joints: Roller joint Load transfer only one direction (vertical direction), when load comes in other direction, the roller just moves.
Pin joint It is very common in construction industry, the force direction can be two
Fixed joint Most complicated to calculate, it can cause a bending or twisting, which depends on the force of loads acting on them
Building system: Structural system includes beam, column and load bearing walls that support floor and roof. Enclosure system: Consist of roof, exterior walls, doors and windows. Mechanical system: Include water supply, heating ventilating and air-conditioning,
sewage system, electric system, communication system, power supply, vertical transportation, fire-fighting and waste disposal. Others: Aesthetic qualities Economic considerations Environment impacts Logbook report: This week’s task was to construct another structure using wood and we are aiming for reaching the ceiling by combining those wooden stick together. Before making the real structure, we drew a design map of this:
When we designed at the beginning, we
thought about making a rectangle for our base, but we found later we did not have enough sticks, which means it might not possible to reach the ceiling, so we did triangle base instead of rectangle one. Step1: making different triangles with different sizes
( We were using glue to stick those joints together, but it did not always work because of different amount of glue, so in order to ensure the structure was fixed at the joint, we choose to use mounting tape and glue together like the followings:
(By doing this, we can separate our task into individual components; those triangles are placed on the plane where the joints are.) Step 2: Putting up sticks and combining them with those triangles. It is the most difficult part of the process because we made it higher and higher, the gravity center might be moving along with process, so the structure is most likely to collapse.
It looks like a tiny example of rigid joints, because we can restrict vertical, horizontal and rotation, in other word, it is completely fixed. To make sure the structure was stable; we also added a small stick between each beam and column.)
(Second level was completed.) Step 3: repeating the same process and finish the product We tried to combine more triangles and joint together and that was what we got at the end of the process:
Efficiency of material and comparison:
Wooden sticks are cut into long and thin shape, so basically their ability of compression may be extremely weak, while stretching ability is better. As we made the structure higher and higher, the triangle base appeared twisted, while rectangle base did not, so the shape of foundation determined the stability of the structure. However, rectangle base costs more sticks, while the efficiency might be the main concern, because that structure can probably not allow us to reach the ceiling within 45 minutes. But generally, making a wooden structure requires a strong understanding of different materials and amount of glue using. Glossary for this week: Structural joint The intersection between beam and column Stability Beam Bracing (supporting component between beam and column)
Frame (basic structure) Tension (opposite to compression)
Reference lists: 1. The Great Wall of China (July 8 of 2012), http://kamonohashikamo.wordpress.com/ 2012/07/08/the-great-wall-of-china/ 2. City Sights ICEF FAM Trip,
http://www.colourfultrips.com/trip-220City-Sights-ICEF-FAM-Trip 3. Modern Water Cube Beijing National Swimming Centre (September 22nd, 2010), homenix http://www.homenix.com/modernwater-cube-beijing-national-swimmingcentre/ 4. Digital Imaging and the Web in Teaching Structures (March 13,1996), Kirk Martini, http://www.arch.virginia.edu/~km6e/tti /tti-summary/part-2.html
5. CENTRAL OFFICE, Hurbanovo, (November 20th, 2009), http://www.streng.sk/?p=107