"Moreover, there is another unavoidable problem with all-steel high-rise buildings, which is that the displacement of the high-rise buildings is too large. In the 1980s and 1990s, people found that all-steel structures could no longer meet the requirements for further increases in building heights. The reason is that the increase in the lateral stiffness of the steel structure could not keep up with the rapid increase in height. In other words, the displacement of the upper part of this all-steel high-rise building due to wind force is much greater than that of the concrete structure."
"This can be clearly seen from the comparison between the Burj Khalifa I designed and the Twin Towers of the World Trade Center. The Burj Khalifa I designed uses a brand new structural system with a concrete lower structure and a steel upper structure. The area from -30 meters underground to 601 meters above ground is a reinforced concrete shear wall system; the area from 601 to 828 meters is a steel structure, of which the area from 601 to 760 meters uses a steel frame with diagonal braces."
"The New York World Trade Center is a full steel structure, so the maximum displacement of the two buildings on one side at 412 meters reached 1000 mm; while the maximum displacement of the concrete structure of the Burj Khalifa at 601 meters was only 450 mm. Even from the perspective of the Burj Khalifa itself, at the top of the concrete structure at 601 meters, the maximum displacement on one side was only 450 mm, but at the top of the steel frame at 760 meters, the maximum displacement on one side rapidly increased to 1250 mm. At the top of the steel mast at 828 meters, the maximum displacement on one side reached 1450 mm. Therefore, the Burj Khalifa arranged the hotel and apartments in the concrete structure below 601 meters, and used the steel structure above 601 meters as an office building. The displacement above is too large, and it is not suitable for living, only for office use."
Hearing this series of data, Yang Jing couldn't help but say in surprise: "Is the gap between the all-steel structure and the concrete structure so big?"
"That's right, the choice of these two building materials creates such a huge difference!" Adrian said with certainty.
The so-called floor displacement refers to a physical phenomenon that is common in super-high-rise buildings. Generally speaking, when the height of a building exceeds a certain limit, it will shift under the action of lateral stress such as wind. This is an inevitable physical phenomenon. The higher the floor, the greater the displacement.
Generally speaking, displacement refers to the amplitude of the building's horizontal shaking from left to right, and unilateral displacement refers to the amplitude of the building's shaking to one side.
The greater the displacement, the more unstable the building is. It's simple: it's shaking too much! If the displacement exceeds a certain limit, the building will shake more and more due to the lateral stress, and eventually collapse. Therefore, the construction industry has strict regulations on the floor displacement coefficient of super high-rise buildings. If the model of a super high-rise building cannot pass the wind tunnel test, it is absolutely forbidden to build the building.
After the design of a super-high-rise skyscraper is completed, several models of different scales will be made for testing. For example, the ratio of the overall model for testing rigidity and aeroelasticity is usually 500:1, while the model used to test local wind research is 250:1 or even 125:1.
This test model can intuitively reflect the impact of lateral stress on the building, thereby determining whether the building's design is qualified.
Adrian continued, "It is precisely because of the huge difference in displacement between all-steel structures and concrete structures that reinforced concrete core tubes plus peripheral steel structures have become the basic form of super-high-rise buildings since the 1980s and 1990s. The Jinmao Tower, Zifeng Tower, Burj Khalifa Tower, Kingdom Tower and Greenland Center that I designed all use this structural form."
"I remember that the design standard of the Burj Khalifa was based on the local strong wind that occurs once every 50 years, that is, 55 meters per second. As a result, when doing wind tunnel tests, the horizontal displacement of the model's structure in the face of strong winds that occur once every 50 years was almost the same as the maximum displacement data tested after the building was built. So, my design at the time was absolutely qualified. Therefore, in the design of this five-star tower, I also adopted a structural form similar to that of the Burj Khalifa and the Kingdom Tower. Although this design has not passed the wind tunnel test, I believe my design should be able to meet the requirements."
"So what you mean is that this Five-Star Tower or the Dragon Building will also adopt this structural form?" Yang Jing asked.
"Yes, this structural form is currently the most suitable for super-high buildings. Well, I mean, this method is the best in terms of funding and ground pressure. Of course, if it can pass the wind tunnel test, it will be even better. Well, you just called this building I designed the Dragon Building?"
"Haha, of course, because I will name this building after my company. Congratulations, Ade, I'll adopt your design!"
PS: I would like to thank "很懒的鱼" for the reward of 100.
Continue read on readnovelmtl.com
