Post tensioning in building structures | Converge.io

June 17, 2023

Post-tensioning is a pivotal technique within modern construction, enhancing the performance of building structures. By applying tension to concrete after it has cured, post-tensioning ensures structural durability and flexibility.

In this article we will explain how post tensioning is used in building structures and what type of buildings that benefit from this method. We also include a section where we give examples of famous buildings built by using the post-tensioning method. 

Read more: We make a comparison between pretensioning and post-tensioning and explain the costs of post-tensioning.

Post-Tensioning in Building Structures: The Process

The post-tensioning process involves strategic steps to enhance the structure's integrity:

  1. Installing Tendons: Post-tensioning tendons, made of high-strength steel, are placed in concrete forms.
  2. Pouring Concrete: The concrete is then poured and left to harden.
  3. Applying Tension: Once cured, the tendons are tensioned using hydraulic jacks and anchored against the outer edges of the concrete.
  4. Grouting: The ducts housing the tendons are filled with grout to protect against corrosion, completing the process.

Advantages of Post-Tensioning in Building Structures

Post-tensioning offers numerous advantages, facilitating the construction of varied building types:

  1. Structural Efficiency: Post-tensioned concrete slabs are thinner than traditionally reinforced slabs, yet they maintain superior strength.
  2. Design Flexibility: The process allows for unique architectural shapes and large open-plan spaces, offering design versatility.
  3. Sustainability: Reduced materials and improved thermal efficiency lower the building's carbon footprint.

Using Post-Tensioning in Different Building Types

The innovative technique of post-tensioning brings unique advantages to various building types. Here are some building types that are most commonly constructed by using post-tensioning:

1. High-Rise Buildings

When constructing high-rise structures, post-tensioning allows for slimmer floor slabs, reducing the overall building height without impacting the number of floors. This technique is beneficial in urban environments where height and weight restrictions may apply. 

Furthermore, the improved structural efficiency reduces the quantity of construction materials required, leading to cost savings and quicker construction times.

2. Commercial Buildings

In commercial structures, such as shopping centres or office buildings, the requirement for large, uninterrupted spaces is paramount. Post-tensioning facilitates the creation of these open-plan areas by minimising the need for load-bearing columns. This creates more aesthetically pleasing and functionally practical spaces. 

Additionally, this structural efficiency enables longer spans, providing opportunities for innovative architectural designs.

3. Residential Buildings

Post-tensioning offers significant benefits in residential construction. For individual homes, the technique can help combat problems associated with soil movement. By enhancing the building's resistance to ground shift, the risk of structural cracks is greatly reduced. 

In multi-storey apartment complexes, post-tensioning allows for thinner floor slabs, increasing the net usable area of each floor and ultimately leading to higher return on investment for developers.

4. Public Infrastructure Buildings

For buildings like schools, hospitals, and libraries, post-tensioning offers the flexibility needed to accommodate the specific spatial needs of these structures. Large, open areas can be created for communal use, while maintaining the building's structural integrity. 

The sustainability aspect of post-tensioning also aligns with public sector goals for environmentally-friendly construction.

5. Sports Facilities

In the case of sports arenas or swimming pools, post-tensioning offers unique solutions. These structures often require large spans and specific shapes. The ability to create unusual, strong forms, such as long cantilevered sections or curved shapes, makes post-tensioning an ideal choice.

The application of post-tensioning is diverse, demonstrating its capacity to improve the efficiency, aesthetics, and functionality of a wide range of building types.

Read more: Learn more about modular house construction and how it compares to traditional construction.

Sports arena with many red seats

Iconic Post-Tensioned Buildings Around the Globe

The use of post-tensioning in building structures has facilitated the construction of some of the world's most iconic and structurally innovative buildings:

Sydney Opera House, Australia

This iconic structure with its distinctive shell-like roofs utilised post-tensioning, allowing the creation of its unique and complex design.

The Shard, London

Standing as the tallest building in Western Europe, The Shard's innovative design was made possible with post-tensioning, providing the necessary strength and flexibility.

Petronas Towers, Malaysia

Once the tallest buildings in the world, these twin skyscrapers implemented post-tensioning techniques to withstand high winds and possible earthquakes.

Incheon Bridge, South Korea

While not a building, this long-span bridge demonstrates the prowess of post-tensioning in a large-scale structure, providing strength and durability.

Burj Khalifa, Dubai

As the world's tallest building, the Burj Khalifa relied on post-tensioning to achieve its record-breaking height and to ensure stability against wind and seismic forces.

One World Trade Center, USA

In its construction, One World Trade Center utilised post-tensioning to achieve its status as the tallest building in the Western Hemisphere, withstanding harsh weather conditions and providing structural safety.

Marina Bay Sands, Singapore

This stunning structure with its distinctive SkyPark resting atop three towers showcases the design versatility of post-tensioning.

These examples illustrate the significant benefits that post-tensioning can bring to complex and ambitious building projects around the world. From skyscrapers to iconic landmarks, post-tensioning plays a crucial role in shaping our built environment.

Marina Bay Sands building in Singapore

Read more: We explain modular construction and its advantages as well as its environmental benefits.

Conclusion: The Role of Post-Tensioning in Future Construction

Looking ahead, post-tensioning will continue to play a significant role in construction. As architects and engineers seek to build more sustainable, efficient and flexible structures, the value of post tensioning in building structures cannot be overstated. Harnessing this innovative technique can unlock significant advancements in the built environment.

Whether high-rise, commercial, or residential, buildings employing post-tensioning stand to benefit from improved structural integrity, efficient use of materials, and unparalleled design flexibility. It is this potent combination that will see post-tensioning continue to shape our architectural landscapes for the better.

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