In this blog post, we’ll explore the principles and architectural significance of the post-tensioning method applied to Marina Bay Sands, a landmark of Singapore.
Marina Bay Sands and Architecture of the Highest Difficulty
In Marina Bay, the heart of Singapore, there is a building that immediately catches the eye. Hailed as a “miracle of 21st-century architecture” and established as Singapore’s iconic landmark, Marina Bay Sands (MBS) is the star of the show. Opened in 2010, Marina Bay Sands consists of three 55-story towers and a massive, ship-shaped SkyPark that connects the three towers at a height of approximately 200 meters above ground. When viewed from the side across Marina Bay, the complex takes on a unique shape that resembles two playing cards leaning against each other; each tower is tilted at a different angle, creating a highly dynamic exterior. This innovative form is not merely a visual feature but also represented a design that demanded an extremely high level of structural engineering expertise. In fact, world-class, cutting-edge structural technology was fully mobilized during the construction process, and the project is regarded as one of the most technically challenging architectural projects in existence. One of the core technologies that made this structure possible is the post-tensioning method.
The Principle of the Post-Tensioning Method: Overcoming Concrete’s Weaknesses
Concrete, which has very high compressive strength, is a material that is strong under compression but relatively weak under tension. While standard structural concrete performs exceptionally well under compression, it can crack relatively easily when subjected to tensile forces—that is, forces that pull on the material. For example, if concrete and steel of the same size are pulled from both ends, the concrete will break easily, whereas the steel will stretch to a certain extent and withstand the load. Due to this characteristic, concrete is considered to have a significantly lower ability to withstand tensile forces than steel.
If a concrete structure is placed on two supports and a uniform load is applied to it, the structure will deflect downward. During this process, the greatest tensile force occurs at the center of the structure, and if this force exceeds the allowable limit, cracks may form. To prevent this problem, in typical reinforced concrete structures, steel bars with high tensile strength are embedded to compensate for the concrete’s weak tensile performance.
The post-tensioning method is a type of prestressed concrete. Unlike conventional reinforced concrete, prestressed concrete is a specialized structural method designed to apply compressive force to the concrete in advance to counteract the tensile forces that arise later. In the post-tensioning method, tubes through which steel cables pass are installed inside the concrete before it is poured, and once the concrete has achieved sufficient strength, the steel cables are pulled and secured using hydraulic equipment. During this process, tensile force is generated in the steel cables, and as a reaction, compressive force is applied to the concrete in advance. As a result, the tensile forces generated when the structure is subjected to actual loads are largely offset, effectively reducing cracks and enhancing the structure’s stability and durability.
Post-Tensioning Technology That Made Marina Bay Sands Possible
Marina Bay Sands also actively applied the post-tensioning method to stably realize its slanted towers and large-scale SkyPark while minimizing complex external support structures. In particular, by leveraging the advantage of efficiently constructing long spans and large-scale structures, the project simultaneously achieved unique architectural beauty and structural stability.
In the past, the post-tensioning method was primarily regarded as a specialized technology used in civil engineering structures such as long-span bridges. However, with recent advancements in architectural technology, it is now widely used across various architectural fields—including super-tall buildings, large-scale commercial facilities, and stadiums—due to its ability to reduce the number of columns and create spacious interiors.
Marina Bay Sands is regarded as a prime example of the combination of a complex design and top-tier construction technology. The success of such projects demonstrates that cutting-edge structural technology can open up new possibilities in architecture. To continue achieving both original design and safety in the future, ongoing research and technological development in advanced structural technologies, such as post-tensioning, will be essential.
