Skyscrapers have become the defining features of modern cities that push beyond the limits of engineering and architectural design. Structural engineering plays a critical role in ensuring the safety and success of every skyscraper.
Importance of Structural Engineering
Structural engineering primarily deals with constructing, analyzing, and designing structures such as skyscrapers and bridges to ensure that the structures are stable and safe and can withstand the forces and loads, including seismic loads, wind loads, live loads, and dead loads, and environmental factors encountered by them during their service life.
Under structural engineering, building design involves the creation of aesthetically pleasing, safe, and functional structures. The design commences by understanding the client's needs, considering the conditions of the construction site, and identifying proper structural systems and construction materials to support the building’s form and function. The design process has several steps, including conceptual design, preliminary design, detailed design, and construction. Computer-aided design (CAD) software is utilized throughout the design process to create three-dimensional (3D) models of the building’s structural system to analyze the behavior of the structure under various forces and loads.
In structural engineering, building information modeling (BIM) is utilized to streamline the construction processes, optimize building designs, and visualize the behavior of buildings under various conditions.
Role of Structural Engineering in Skyscrapers
The massive gravitational load exerted by the skyscraper’s weight is the most significant challenge in skyscraper design. Innovative systems are developed by structural engineers to support these loads while ensuring occupant safety. A combination of advanced composite materials, concrete, and steel is typically used in skyscrapers to overcome this challenge. Concrete cores and steel frames can efficiently distribute the weight to provide stability against gravitational forces.
Skyscrapers have to be highly resilient against earthquakes, specifically in regions that are prone to seismic activity. Seismic design principles, such as energy-dissipating devices and base isolators, must be implemented by structural engineers to dissipate and absorb seismic forces/ground motions to protect the occupants and surrounding structures.
The moment-resisting frame construction technique can also be employed to design a skyscraper for earthquake resistance. In this construction type, a series of columns and beams are connected in a manner that allows them to resist the force of the shaking during earthquakes. Moreover, the overall risk of a skyscraper’s collapse due to seismic activity can be reduced by providing redundancy in the structural system.
Structural engineering is crucial for wind-proofing skyscrapers as these extremely tall buildings experience much higher wind forces compared to other buildings as they are flexible and have a large surface area, which causes them to sway or even collapse in a few situations during powerful winds. Thus, structural flexibility and aerodynamics are considered for designing wind resistance. Several modern skyscrapers feature distinct shapes, such as tapered profiles and setbacks, to decrease wind pressure.
One or multiple concrete cores can also be built into the center of the building to prevent heavy swaying. Additionally, dynamic systems such as tuned mass dampers are integrated into skyscrapers to counteract swaying and maintain structural stability during storms.
For example, the Tapei 101 skyscraper in Taiwan consists of one of the largest mass damper systems/Gyroscopic stabilizers in the world, weighing approximately 728 tons to counteract the severe impacts from typhoon winds and seismic activity that can impact the structure. The Gyroscopic stabilizer reduces the overall movement significantly when the skyscraper starts to sway due to these effects to prevent structural failure.
The ground conditions and foundations are other crucial aspects that affect the safety of skyscrapers. Structural engineers determine the appropriate foundation type for a skyscraper by assessing the geotechnical and soil conditions of the construction site. Deep foundations, such as caissons or piles, are primarily selected for these extremely tall structures to support their immense weight and ensure structural stability.
Construction materials heavily influence the design of a skyscraper. Novel materials, such as advanced steel alloys and ultra-high-strength concrete, are used during construction to improve the load-bearing capacity and minimize the amount of material utilized in the structure. Additionally, sustainable materials are increasingly being used for construction due to the growing emphasis of the construction industry on environmental responsibility.
Structural engineering is also important for ensuring the comfort and safety of occupants in a skyscraper. Structural engineers ensure that emergency systems, fire resistance, and escape routes are seamlessly integrated into the building design. They coordinate with architects to create inviting, open spaces that offer panoramic views without affecting the structural reliability of the building.
For example, the Canton Tower in Guangzhou, China, is the fifth tallest freestanding structure in the world, with a height of 610 m. The building contains a torqued steel lattice structure built up from 1100 nodes and a similar amount of connecting bracing- and ring pieces and a reinforced concrete inner structure. Source
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