DOES 9/11 KEEP YOU AWAY FROM SKYSCRAPERS?
Taipei 101 Tuned Mass Damper. Source: Wikipedia Commons.
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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. Earthquake-Resistant 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. Fire-Resistant 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? |
相信对很多人来说9/11事件仍然记忆犹新。当人们讨论超高层建筑时，也许会不由自主地提出这个问题：在摩天大厦里工作/生活是否依然安全？
建筑安全是建筑建设中最首要的考量。我们的建筑师及工程师同行们一直在建筑安全领域做出不懈努力，也收获了不少成果，从而保障建筑体内人们的生命安全。 一般说来，地震及火灾是威胁建筑安全的两大灾难。因此相应的建筑抗震及防火技术也在不断发展。 抗震 在日本，经过抗震设计的摩天楼在9级地震中只会轻微摇晃，不受任何损害地完整保留下来。这是经过实践证实的。那么这一目标是如何达到的呢？结构工程师研究出许多非常复杂的技术系统去确保建筑能在各级地震中保存完整不倒。 例如，大楼的基础隔震技术。轴承垫被置于建筑体与地基之间用以缓冲地震对建筑体的影响。 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。 防火/抗火 国际建筑规范中对防火等级及其相对设施有详细规定。抗火材料可减缓火灾蔓延的速度。设置火灾和浓烟障碍物来减缓烟火的扩散可为建筑内人员撤离提供足够时间。 在美国，最大的防火等级能达到4小时。“然而，结构工程师们从未预料到带着如此大量燃油的大型飞机撞向塔楼楼身，由此引发的大火穿透建筑的防火保护，减弱了钢筋的强度，从而导致双子塔大楼坍塌。”《垂直城市》的作者Kenneth King解释道。 "大楼的轻质结构和中空设计的建筑形态使得大量飞机燃料在楼内迅速扩散，并在多楼层内同时引起大火。" "哈山·阿斯塔内，加州大学伯克利分校的一位建筑工程教授对双子塔事件的解释是这样的：大火高温弱化了钢结构横梁及柱结构的承受力，使它们变得柔软脆弱并最终失去了承受整个大楼的能力。"--- 世界贸易中心为何倒塌？刊载于《科学，工程，思索》杂志 安全出口 建筑安全设计的终极目标是保护生命。也就是说，一座能为内部人员疏散赢得足够时间的建筑便可视为成功。因此，安全出口/紧急出口设施也是建筑安全中关键的一环。 根据建筑类别，楼层，以及容纳人数的不同，每座建筑都要求有足够数量的安全出口通往户外安全区域。一座建筑的安全出口越多，越能在短时间内让所有人顺利逃出户外，进入安全区域。 因此，如果我们在设计摩天大楼群落时不仅在地面几层相互链接，而且在高空中也有天桥连接，那么在身处大楼顶部的人们就能更快速的经由天桥逃生到另一座安全的建筑中去。 在垂直城市的设计理念中，城市/社区就是如此的三维度发展：用天桥及平台将建筑与建筑，建筑与户外空间从高空中连接起来。从而给垂直生活提供便捷，也为人们提供更多逃生通道。 任何建筑设计与施工都是需要严格遵守建筑行规的。而对于垂直城市这样全新的城市形态及建筑群落，更是十分需要业界对其进一步研究与开发，进而更新相应的建筑规范及条例，如此才能够最终将其实现。在这之前还有很长的路要走，而我们坚信它的可行性，因为这是大势所趋，随应自然与人类共同发展--绿色设计--的方向。你觉得呢？ |
This article was archived on December 17, 2015.