This article explores the three most significant systems used in tall buildings: moment-resisting frames, shear walls, and tubular structures.
Tall buildings stand as symbols of ambition and progress. They redefine skylines, attract global attention, and demonstrate advances in both engineering and architecture. Yet their impact goes beyond height and form. The real measure of their success lies in the structural systems that allow them to rise safely, withstand environmental forces, and remain adaptable for decades.
Behind every glass façade and striking silhouette, engineers make careful choices about balance. Strength, stability, flexibility, and efficiency must work together, often within the limits of budget, materials, and local conditions. These choices determine not only how high a building can go but also how comfortable it will feel inside, how long it will last, and how much it will cost to maintain.
This article explores the three most significant systems used in tall buildings: moment-resisting frames, shear walls, and tubular structures. It examines their history, strengths, and limitations, and shows how each has contributed to the evolution of tall building design. Case studies illustrate their practical use, while the conclusion looks ahead to the innovations shaping future skylines.
Moment-Resisting Frames
Moment-resisting frames represent one of the earliest structural systems developed for tall buildings. They consist of beams and columns rigidly connected so that the joints resist bending as well as vertical loads. This creates a skeleton that can carry both gravity forces and lateral forces such as wind or earthquakes. The system’s strength lies in its simplicity and versatility.
One of the main attractions of moment frames is the freedom they offer for interior space. Because stability comes from the rigid connections rather than solid walls, large open floors can be created without many obstructions. This makes the system particularly well suited to office towers, where layouts often change as tenants come and go. Architects also value the freedom it gives to design façades that are not constrained by continuous vertical walls.
Despite these advantages, moment frames become less efficient as buildings grow taller. As the number of stories increases, the beams and columns must be made larger and stronger to control sway. This reduces usable space and increases costs. Beyond about forty to fifty stories, pure moment frames are rarely used because they cannot resist lateral forces efficiently. Nevertheless, for medium-height towers, their adaptability continues to make them a reliable choice.
Shear Walls
Shear walls offer a very different solution to the challenge of stability. These vertical walls of reinforced concrete act like deep beams, resisting both vertical loads and lateral forces. They provide stiffness and strength that significantly reduce building sway, making them ideal for tall residential towers where occupant comfort is a priority.
The efficiency of shear walls lies in their ability to create rigid cores. Elevators and staircases are often enclosed by these walls, which then double as the structural backbone of the building. By transferring forces directly into the foundation, shear walls limit lateral displacement even under strong winds or seismic activity. This makes them essential in regions prone to earthquakes, where ductility and energy absorption become critical to safety.
The trade-off, however, is reduced flexibility. Shear walls impose fixed layouts, which makes large open spaces more difficult to achieve. Openings for windows and doors can weaken them, requiring careful design to avoid stress concentrations. For residential buildings, this limitation is less of a concern since repeated unit layouts align well with the system. In offices or mixed-use towers, the lack of adaptability can be a disadvantage.
Tubular Systems
The development of tubular systems in the 1960s revolutionized tall building design. Instead of relying solely on frames or walls, engineers began treating the building’s perimeter as a stiff tube. Closely spaced columns connected by deep spandrel beams formed a rigid exterior that resisted lateral forces much more effectively than interior frames.
The framed tube, first introduced by Fazlur Khan, allowed towers to reach new heights with remarkable efficiency. Later variations such as the braced tube and bundled tube expanded possibilities even further. In the braced tube, diagonal bracing across the façade provided additional stiffness, while in the bundled tube, multiple tubes were combined to create an even stronger system. These developments made it possible to construct buildings that were not only taller but also lighter and more economical.
The John Hancock Center and Willis Tower in Chicago stand as iconic examples of tubular design. Their success demonstrated that tall buildings could be both structurally efficient and architecturally expressive. By moving structural elements to the perimeter, tubular systems freed interior space for flexible use while dramatically reducing the amount of material required. For supertall towers, tubular approaches remain the most practical option today.
Comparing the Systems
Each of these systems reflects a different balance of strength, flexibility, and efficiency. Moment-resisting frames are best for moderate heights where interior adaptability is important. Shear walls are suited to tall residential or seismic-prone buildings where rigidity matters most. Tubular systems dominate the tallest structures, offering unmatched efficiency and the ability to soar to extreme heights.
The choice between them depends on building function, cost, site conditions, and architectural vision. No single system is universally superior. Instead, engineers must weigh the unique demands of each project and often combine systems into hybrids that take advantage of multiple strengths.
Figure suggestion: Diagram comparing structural load paths in frame, shear wall, and tubular systems.
Beyond Efficiency: Other Considerations
While structural performance is central, engineers also evaluate fire resistance, durability, and adaptability. Concrete shear walls provide inherent fire protection, while steel frames require fireproofing measures. Steel is vulnerable to corrosion but offers lightness and speed of construction, whereas concrete can crack under certain conditions but resists decay better.
Adaptability over the building’s lifetime is another consideration. Office towers benefit from the flexibility of frames, while residential towers rely on the stability of shear walls. Tubular systems strike a balance, but their rigid exteriors can complicate changes to façades or openings. Maintenance and life-cycle costs often influence system choice as much as initial strength.
Case Studies in Practice
The Empire State Building, completed in 1931, illustrates the use of a steel frame for a tall office tower. Its rapid construction highlighted the advantages of the frame system, though its noticeable sway revealed the limits of the approach at great heights.
In Mexico City, Torre Mayor uses a combination of shear walls and outrigger systems to provide resilience against earthquakes. Its performance during seismic events has validated the strength and reliability of this design strategy.
The John Hancock Center showcases the braced tube, with its external diagonals forming both structure and architectural expression. The Willis Tower, meanwhile, demonstrated the bundled tube concept by uniting several smaller tubes into a single form, achieving stability and efficiency at great height.
Finally, the Burj Khalifa in Dubai shows how hybrid systems dominate in the twenty-first century. Its buttressed core, essentially a refined version of shear walls integrated with tubular principles, allowed it to rise to unprecedented height while maintaining stability under strong desert winds.
Future Directions
The future of tall buildings will be shaped by digital design tools and sustainable materials. Parametric modeling enables engineers to test countless variations of complex geometries, ensuring both efficiency and beauty. Smart materials and real-time monitoring systems are being integrated into structures, allowing them to respond dynamically to wind or temperature changes.
Timber, reimagined through cross-laminated panels and laminated beams, has returned as a contender for tall structures. When used in combination with steel or concrete, it offers a sustainable and renewable solution. Lightweight composites such as carbon fibre are also under development, promising even greater strength-to-weight ratios.
Environmental technologies are increasingly embedded in roof and façade systems. Solar panels, rainwater harvesting, and natural ventilation integrate structural and environmental design into one seamless whole. These innovations suggest that the next generation of tall buildings will not only be taller but also greener, smarter, and more resilient.
Conclusion
The evolution of tall building systems tells the story of engineering progress. Frames gave buildings flexibility, shear walls offered rigidity, and tubular systems unlocked the potential for supertalls. Each system reflects both the challenges and ambitions of its time.
Also See: [Update] Fundamentals of Tall Building Design
Sources & Citations
- Ali, M.M. & Moon, K.S. (2007). Structural developments in tall buildings: Current trends and future prospects. Architectural Science Review, 50(3), 205–223.
- Smith, B.S. & Coull, A. (1991). Tall Building Structures: Analysis and Design. Wiley, New York.
- Taranath, B.S. (2016). Structural Analysis and Design of Tall Buildings: Steel and Composite Construction. CRC Press, Boca Raton.
- Khan, F.R. (1969). Recent structural systems in steel for high-rise buildings. Proceedings of the British Constructional Steelwork Association Conference on Tall Buildings, London.
