DOES 9/11 KEEP YOU AWAY FROM SKYSCRAPERS?
by Karen Zhang, VerticalCity.org
One may easily recall the 9/11 tragedy when comes to high-rise. Question is always there: how safe it is to stay in a skyscraper?
Building safety is always the very top concern in architecture development. Our professionals have been making their effort and achieved to ensure life safety within building.
Generally, earthquake and fire are two major disasters against building safety. Earthquake- and fire-resistant building is therefore developed to solve the problem.
Evidence has shown that earthquake proof skyscraper in Japan will gently sway and survive in a level 9 earthquake. How could a building achieve this? Engineers have developed many sophisticated methods to protect buildings during all levels of earthquake.
Take the base isolation technique for example. Bearing pad is used to attach between the building and foundation to reduce the impact to the above structure from the foundation when earthquake hits.
Another example is Taipei 101, the tallest building in the world when it opened in 2004. On the top levels of the building there is a tuned mass damper. It will move in the opposite direction during earthquake to reduces the amplitude of building vibrations.
International Building Code has fire rate requirement for all types of buildings. There’s fire-resistant materials to slow down the process of a fire. Barrier to fire and smoke spread is also integrated into building system to earn long enough time for building to evacuate its occupants.
The maximum fire rating in the U.S. is four hour. ‘However, the engineers never anticipated such a large aircraft deliberately flew into the building carrying such large quantity of fuel. It's the fire that penetrated the fire protection, weakened the steel and caused the collapse of the Twin Tower.’ Kenneth King, the author of Vertical City stated.
‘The light construction and hollow nature of the structures allowed the jet fuel to penetrate far inside the towers, igniting many large fires simultaneously over a wide area of the impacted floors.’
“Hassan Astaneh, a structural engineering professor at the University of California at Berkeley, explained that the high temperatures in the fires weakened the steel beams and columns, causing them to become "soft and mushy", and eventually they were unable to support the structure above. “ ---Why Did the World Trade Center Collapse? Science, Engineering, and Speculation
Means of Egress
After all, the goal for building safety is to preserve life. In other words, a building that withstands long enough time to allow its inhabitants to escape is considered a success. Therefore, means of egress (emergency exit) is also the critical factor.
Buildings are required to have enough quantity of enclosed exits to outdoor/safe area according to different building types, numbers of stories and occupancy capacity. The more exits the building can provide, the faster for all its people to escape to outdoor/safe area.
Therefore, if we can connect the skyscrapers not only close to the ground level, but also on upper part of the buildings, chances for people from the higher floors to escape from the single building are better.
In the concept of Vertical City, urban/communities develop 3-dimensionally with sky bridges and platforms connecting the nearby buildings and outdoor, to provide easier access for living environment and more exits for safety.
Architecture design and construction is required to strictly follow the building code and regulation. For such a new urban form and building mass as the Vertical City, more study and research is needed, following by new building code and regulation updating. There’s still a long way to go, however, we believe it’s a promising future. It’s the need and trend to be sustainable for both the nature and living environment. Don’t you think so?
又如，台北101大楼 ---- 2004年投入使用时为世界的最高建筑 ---- 采用的调谐质量阻尼技术。设计者在大楼顶部悬挂了一个巨型质量阻尼器，通过阻尼器以与建筑摇晃相反的方向来回移动，以减少地震对大楼的冲击。
This article was archived on December 17, 2015.