Tokyo Skytree: The Second Tallest Tower in the World - Case Study Example

Tokyo Skytree Name Institution Lecturer Course Date Tokyo Skytree Tokyo Skytree is located in Japan’s capital city, Tokyo, and specifically in Sumida (Japan Guide, 2013). The skyscraper, whose construction work began in 14th July, 2008, took four years under construction and was officially opened on 22nd May, 2012 (Japan Guide, 2013). By 2010, the building, which serves as an observation tower, houses a restaurant and used for broadcasting purposes, became the tallest building in the country even before it reached its full design height of 634 meters. The building reached its full height in 2011 becoming the second tallest building in the world trailing behind Dubai’s Burj Khalifa, which is 828 meters tall (The Telegraph, 2013). It has 32 floors and was constructed following the metamodernism architectural style (Foster, 2012). Tokyo Skytree is the landmark of Tokyo and Japan at large serving as a broadcasting tower for Tokyo. The building houses a shopping complex located at its base and a number of restaurants located in various parts of the building. The building also houses various offices and acts as a tourist attraction center particularly its two observation decks located at 350 meters and 450 meters high respectively as shown in figure 1 (Japan Guide, 2013). Figure 1: A detailed description of Tokyo Skytree. As shown in the figure, the building has a large base that houses various facilities including shops, restaurants, aquarium, planetarium and offices. The first observation deck is located 350 meters from the ground level while the second observation deck is located 450 meters above the ground level. The building narrows towards the top with fewer facilities being located as one moves up. For instance, the second observation deck does not have a restaurant (Japan Guide, 2013). Figure 2: An aerial view of Tokyo’s Skytree. As shown in the figure, the observation decks are well above other buildings so that people can view the surrounding when in the first observation deck. Therefore, people in the restaurant in the first observation deck can have an aerial view of the surrounding (Japan Guide, 2013). Figure 3: This figure shows how the building and especially the observation decks are designed to allow people to have an aerial view of the surrounding. Metallic guides can be seen to offer protection while glass covering facilitates viewing making the building a notable tourist attraction site (Japan Guide, 2013). Essential Engineering properties of Tokyo Skytree Design work of the tower started long before the beginning of construction works on the building; publication of the towers design was done on 24th of November, 2006 (The Telegraph, 2013). The design of the building considered three key issues: 1. The design considered disaster prevention in which the design of the building focused the security and safety aspect of the building. Security and safety aspect was considered for the occupants and users of the building, as well as neighboring people and buildings. The building was also designed to withstand seismic loadings considering that region is usually prone to earthquake activities (Foster, 2012). 2. The design of the building considered the tradition aspect of Japan yet considering the futuristic aspect of the building. In fact, 634 (the height of the building in meters) is symbolic (Musashi), which is a historic name of Tokyo region (Japan Guide, 2013 & Japan National Tourism Organization (JNTO), 2013). 3. The design considered the revitalization of Sumida and the larger Tokyo city (Foster, 2012) The design of the tower has two key shapes: tripod and cylindrical shapes. The lower half of the tower, up to about 350 meters from the ground, has a tripod shape while the structure of the tower above 350 meters is cylindrical-shaped as shown in figure 4. Figure 4: Structural shape of the tower. As shown in the figure, the lower parts of the building are completely tripod-shaped. The building assumes a cylindrical shape slowly as ones moves up. At a height of about 320 meters above the ground level, the structure of the building is cylindrical. The figure also shows that the building narrows as it becomes taller implying that the cross section area of the building is greatest at ground level and smallest at the topmost part of the building (Foster, 2012). The building narrows towards the top meaning that the cross section area of the building is greatest at the base and smallest at the top. Similarly, the design of the skytree is such that the weight of the live and dead weights of the building reduces towards the top of the building. This is evidenced by the shape of the building, which narrows towards the top implying that dead weight (weight of the building owing to the materials making the building) reduces towards the top of the building. Additionally, as seen in figure 1, there are lesser facilities as one move up the building. For instance, the base of the building houses more facilities than the first observation deck. The second observation has fewer facilities than the first observation deck. Further, owing to the fact that the cross section area of the building reduces as one move up the building, it is clearly evident that there are fewer facilities as you move up the building, which, consequently, reduces live weight on the building progressively towards the top. These are essential engineering design properties of the building that allow the building to enjoy the center of gravity concept. From physics, it is well known that the stability of bodies is largely dependent on the height of the center of gravity from the base. The higher the height, from the base, of the center of gravity, the less stable is the body. Center of gravity is all about where the line of action of the mass of the body is located. Locating this line of action through the center of the body, through equal distribution of masses around the body, further enhances the stability of the building. Ensuring that the center of gravity of tall building remains below the floor is the easiest method of maintaining stability of the building. This is further enhanced by progressively reducing the weight of the building as one moves up further from the floor level. Consider, for example, the figure shown below. The buoy shown in figure 5 has a wide base than its upper parts. The base is also heavy thereby lowering the height of the center of gravity so that it is below the surface of the water. The low center of gravity prevents the buoy from tipping over even when subject to drafts. The wide base also prevents the buoy from tipping over when there are changes in mass concentration on the upper parts. For example, if a rider hangs the head to observe the water below, there are changes in mass distribution that tends to incline the buoy towards the high concentration areas. The wider base acts as a wide foundation that prevents the body from tipping over. Figure 5: Illustrating stability concept using a buoy The Tokyo Skytree employs the same principle. Firstly, the design of the building is such that the center of gravity is below the surface level thereby preventing the building from collapsing due to lack of stability (Foster, 2012). This is further enhanced by the shape of the building, which assumes a tapered shape like a cone. Every cross section of the building acts as the base of the upper parts. According, every cross section part of the building has a wider base so that applied loads in every floor operate within the base of the respective flow. The shape prevents the building from collapsing especially when subject to horizontal loading, such as wind loads. Consequently, the skytree is more stable than block-shaped skyscrapers, such as Densu Building (figure 6). Figure 6: This figure shows that shape of Densu building (213.34 meters tall), which is not tapered compared to Tokyo Skytree (Mobile Reference, 2007). The cylindrical shape of the upper parts of the building is another essential engineering design aspect of the building. The cylindrical shape allows the building to distribute horizontally applied loads, such as wind loads evenly around the building thereby preventing collapse under such loads. When wind loads hit the building from one side, the cylindrical shape of the building enables the loads to be distributed to the other sides such that all structural members react to the load as opposed to rectangular or square shapes where some structural members experience higher loading than others in case of wind loads leading to collapse. Comparing the Tokyo Skytree and Densu building, Tokyo Skytree is likely to withstand heavier wind loading than the Densu building. The cylindrical shape also serves aerodynamic purposes as opposed to Densu building whose shape gives the building a large surface area for wind to act. The buildings can be considered as bodies moving in the air thereby being subject to wind loading. Wind loads are dependent on the speed of the wind and surface area of the face that the wind acts on, as well as the shape of the surface that the wind acts on. In this case, the shape of the face is of importance. There is minimum perpendicular face for the wind to hit in the case of cylindrical shapes as opposed to any other shape. Therefore, winds hitting the Tokyo Skytree will produce minimum loads as much of the wind will be forced to drag around the building thereby distributing the force. On the contrary, winds hitting the Densu building, especially the wide face, will produce high wind loads thereby increasing the risks of collapse. Figure 7: this figure demonstrates how cylindrical-shaped building experience lighter wind loads compared to rectangular-shaped buildings. Cylindrical-shaped buildings have the minimum face of action of wind loads owing to their shapes while flat surfaces on rectangular shaped buildings offer large surface areas for wind action. In the case of cylindrical shaped buildings, wind loads are distributed around the building because the shape forces wind to drag around the building. Therefore, in case of wind loads, cylindrical-shaped buildings will be less likely to collapse compared to buildings having other shapes. References Foster, M. (2012). Tokyo Sky Tree Opens as the World's Second Tallest Tower. The Huffington Post. Retrieved August 12, 2013, 2013 from http://www.huffingtonpost.com/2012/04/17/tokyo-skytree-opens-as-th_n_1430759.html Japan Guide. (2013). Tokyo Skytree. Retrieved August 12, 2013, from http://www.japan-guide.com/e/e3064.html Japan National Tourism Organization. (2013). Tokyo Sky Tree. JNTO. Retrieved August 12, 2013, from http://www.jnto.go.jp/eng/location/spot/comcobtw/tokyoskytree.html Mobile Reference. (2007). Travel Tokyo, Japan: Illustrated City Guide, Phrasebook, and Maps. MobileReference The Telegraph. (2013). Tokyo Skytree: The Second Tallest Tower in the World. Telegraph Media Group Limited. Retrieved August 12, 2013, from http://www.telegraph.co.uk/property/propertypicturegalleries/9209393/Tokyo-Skytree-the-second-tallest-tower-in-the-world.html Read More

The building was also designed to withstand seismic loadings considering that region is usually prone to earthquake activities (Foster, 2012). 2. The design of the building considered the tradition aspect of Japan yet considering the futuristic aspect of the building. In fact, 634 (the height of the building in meters) is symbolic (Musashi), which is a historic name of Tokyo region (Japan Guide, 2013 & Japan National Tourism Organization (JNTO), 2013). 3. The design considered the revitalization of Sumida and the larger Tokyo city (Foster, 2012) The design of the tower has two key shapes: tripod and cylindrical shapes.

The lower half of the tower, up to about 350 meters from the ground, has a tripod shape while the structure of the tower above 350 meters is cylindrical-shaped as shown in figure 4. Figure 4: Structural shape of the tower. As shown in the figure, the lower parts of the building are completely tripod-shaped. The building assumes a cylindrical shape slowly as ones moves up. At a height of about 320 meters above the ground level, the structure of the building is cylindrical. The figure also shows that the building narrows as it becomes taller implying that the cross section area of the building is greatest at ground level and smallest at the topmost part of the building (Foster, 2012).

The building narrows towards the top meaning that the cross section area of the building is greatest at the base and smallest at the top. Similarly, the design of the skytree is such that the weight of the live and dead weights of the building reduces towards the top of the building. This is evidenced by the shape of the building, which narrows towards the top implying that dead weight (weight of the building owing to the materials making the building) reduces towards the top of the building.

Additionally, as seen in figure 1, there are lesser facilities as one move up the building. For instance, the base of the building houses more facilities than the first observation deck. The second observation has fewer facilities than the first observation deck. Further, owing to the fact that the cross section area of the building reduces as one move up the building, it is clearly evident that there are fewer facilities as you move up the building, which, consequently, reduces live weight on the building progressively towards the top.

These are essential engineering design properties of the building that allow the building to enjoy the center of gravity concept. From physics, it is well known that the stability of bodies is largely dependent on the height of the center of gravity from the base. The higher the height, from the base, of the center of gravity, the less stable is the body. Center of gravity is all about where the line of action of the mass of the body is located. Locating this line of action through the center of the body, through equal distribution of masses around the body, further enhances the stability of the building.

Ensuring that the center of gravity of tall building remains below the floor is the easiest method of maintaining stability of the building. This is further enhanced by progressively reducing the weight of the building as one moves up further from the floor level. Consider, for example, the figure shown below. The buoy shown in figure 5 has a wide base than its upper parts. The base is also heavy thereby lowering the height of the center of gravity so that it is below the surface of the water.

The low center of gravity prevents the buoy from tipping over even when subject to drafts. The wide base also prevents the buoy from tipping over when there are changes in mass concentration on the upper parts. For example, if a rider hangs the head to observe the water below, there are changes in mass distribution that tends to incline the buoy towards the high concentration areas. The wider base acts as a wide foundation that prevents the body from tipping over. Figure 5: Illustrating stability concept using a buoy The Tokyo Skytree employs the same principle.

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