This blog post examines how well supertall buildings can be prepared for various disasters like earthquakes, wind, and fire from diverse technical perspectives.
Super high-rise buildings refer to structures over 200 meters tall or with 50 or more floors. Currently, super high-rise construction is actively underway worldwide. Building these structures requires significant cost and time. However, they are not only high-value real estate assets themselves but also have the potential to become iconic tourist destinations representing their countries, driving construction efforts in many nations. Particularly in major cities, where land is limited, skyscrapers are gaining attention as the most realistic alternative for accommodating larger populations. Yet, separate from their economic value, many people question the safety of these massive structures.
Are skyscrapers truly safe? This doubt is further emphasized by disaster movies featuring skyscrapers. For instance, films depicting fires or structural collapses caused by aircraft crashes fuel public anxiety, and such safety controversies persist. While numerous factors must be considered to maintain skyscraper safety, three are particularly crucial: how they withstand earthquakes, wind, and fire.
All buildings are designed with consideration for their earthquake resistance. For supertall structures, earthquake preparedness is even more critical. Since earthquakes are unpredictable natural disasters, the seismic performance of the structure is essential. For instance, the world’s tallest building, the Burj Khalifa, was constructed using ultra-high-strength concrete with a compressive strength of 80 MPa. This strength is so robust that a concrete block the size of a dice could support ten adult men weighing 70kg each, and it possesses the capability to withstand a magnitude 7.0 earthquake. The core wall, the central structural element of a supertall building, acts as the building’s spine during an earthquake. Using such powerful materials effectively disperses the shock of the earthquake.
Beyond earthquakes, another major challenge for skyscrapers is wind. Skyscrapers are more significantly affected by horizontal vibrations caused by wind than by seismic loads. While wind strength varies depending on atmospheric stability, it generally increases with altitude. Wind pressure, known as wind load, increases proportionally to the square of wind speed. Consequently, wind load grows exponentially with height. For example, comparing a 30-meter-tall building to a 90-meter-tall building, the height difference is threefold, but the wind-induced impact increases by approximately nine times. For this reason, supertall buildings require flexible designs to withstand strong winds. This involves designing the structure to respond flexibly to wind forces, thereby absorbing wind pressure and minimizing vibrations. A key technology used for this purpose is the damper. A damper is a device that absorbs vibrational energy to enhance the building’s stability, typically installed as a large pendulum or a water-filled tank. When a building leans due to wind, the damper moves in the opposite direction to restore balance.
While supertall buildings can prepare to some extent for natural phenomena like earthquakes and wind, the risk of fire remains a significant challenge. Evacuation can be particularly difficult in supertall buildings during a fire, making fire prevention and initial response critically important. Therefore, various safety devices and designs are essential in supertall buildings to minimize damage in the event of a fire. For example, supertall buildings use materials with high fire resistance to buy evacuation time during a fire. Most buildings employ ultra-high-strength concrete capable of withstanding exposure to high temperatures for over three hours or apply fire-resistant cladding technology to enhance fire resistance. Fireproof cladding is a technique that protects the building’s structural elements using fire-resistant bricks, fireproof mortar, or metal alloys, designed to withstand temperatures between 1200°C and 1800°C for extended periods.
Furthermore, many countries mandate the creation of a refuge safety zone every 30 floors in supertall buildings. These zones play a crucial role in aiding evacuation during a fire, and the installation of dedicated evacuation elevators is also mandatory, enabling the simultaneous evacuation of large numbers of people. However, these design elements alone are insufficient. For supertall buildings, annual safety inspections must be conducted, and emergency evacuation drills must be held to ensure efficient response in the event of an actual fire.
Ensuring the safety of supertall buildings thus requires comprehensive consideration of various factors like earthquakes, wind, and fire. Beyond this, however, countless other considerations must be addressed during supertall building design. For instance, research and development into building energy efficiency, environmental impact, and methods for decommissioning supertall structures are also ongoing. Additionally, issues concerning the cleaning and maintenance of high-rise windows in skyscrapers are also significant. These problems require particular attention not only for maintaining the building’s appearance but also because they are directly related to the building’s structural stability. Ultimately, buildings are public assets used by many people, and a single accident can result in significant loss of life. Therefore, designs must consider every possible scenario.
Therefore, while concerns about the safety of supertall buildings are somewhat understandable, these worries are largely alleviated by the various technological advancements and rigorous safety management in place. Supertall buildings are not merely tall structures; they symbolize cutting-edge technology and humanity’s spirit of challenge. Their potential for future development remains boundless.
