In structural design, a key issue is how to make buildings resistant to earthquakes and wind.

When the frequency of wind vibration matches the building's vibration frequency, the building will "dance with the wind," a phenomenon known as resonance.

When resonance exceeds a certain amplitude, it can affect the building's use, pose safety hazards, and cause discomfort for occupants. In the design of tall buildings, wind resistance must meet design requirements for strength, stiffness, comfort, and fatigue resistance to ensure the structure remains safe under wind loads, preventing collapse, cracking, or excessive displacement.

To unlock the "secret" behind wind resistance, we must first understand structural wind engineering.

In simple terms, structural wind engineering is a discipline that utilizes theories from meteorology, bluff-body aerodynamics, structural random vibration, and various methods such as wind tunnel tests, field measurements, or numerical simulations to analyze and assess the displacement, acceleration, and wind environment around buildings under wind loads, ensuring structural safety and comfort.

In structural engineering, the focus lies on the wind resistance design of the main structure. The main structure refers to the system that resists external loads such as gravity, earthquakes, and wind, such as the frame-core tube and nested tube systems commonly used in super-tall buildings today.

The wind tunnel experiments show that the wind force near the edges of rectangular sections is more significant than that in the middle. Using sections closer to streamlined shapes helps reduce wind loads at the edges, thus reducing the total wind force on the building. For example, the shapes of airplanes and high-speed trains are designed to be streamlined to reduce wind resistance.

Modern buildings also employ structural control methods to resist wind, such as installing dampers at specific locations within the building.

Dampers provide damping when the building vibrates, reducing the vibration and ensuring building safety. They are also humorously referred to as "guardian artifacts" by netizens.

There are three primary forms of dampers: the first is to add a cross-brace between the building's support columns to reduce the deformation of the support columns and thus reduce vibration amplitude; the second is to add dense material within the walls to absorb vibration energy and weaken vibration; the third is to suspend a mass block at the top of the building, swinging in the opposite direction of the building's vibration to dampen the vibration.

For earthquake resistance, the shape of the building significantly impacts its seismic resistance. Therefore, one of the tasks of structural engineers is to persuade architects to adopt more regular shapes.

According to earthquake and wind resistance requirements, the best solution is the least distinctive shape, such as a cylindrical or regular polygonal shape. If you carefully observe most super-tall buildings over 400 meters worldwide, you'll find that the majority adopt such shapes.

However, for most ordinary high-rise buildings, architectural design pursues diversity and uniqueness and cannot accept rigid shapes. The conflict between structural engineers and architects is almost irreconcilable.

The inherent seismic and wind resistance of a building often depends on whether structural engineers or architects have the upper hand in the conflict. For example, structural engineers usually prevail in Japan, resulting in highly regular shapes for high-rise buildings with simple column grids and flat elevations.

The collaborative efforts of structural engineers and architects play a crucial role in ensuring the safety and resilience of buildings against wind and seismic forces. While conflicts may arise between the pursuit of structural integrity and architectural aesthetics, finding a balance is essential for creating structures that are not only visually striking but also inherently robust in the face of natural elements.