The Role of Post-Tensioning in Sustainable Tall Building Construction

Aleksey Gorilovsky
Stein Ltd., St. Petersburg

As cities continue to grow and densify, there is a greater push to create vertical communities. Tall building construction is booming in many parts of the United States with cities such as New York, Chicago, and Honolulu seeing an increase in the construction of tall buildings. Many of these tall buildings are constructed with reinforced concrete, which offers many benefits such as greater stiffness, robustness and lesser total height to accommodate similar number of floors in comparison to a structural steel building. More and more of these buildings are utilizing post-tensioned concrete systems for floor slabs, transfer girders and even in vertical elements such as shear walls.

Post-tensioned concrete offers many advantages such as the ability to span longer, cantilever farther and accommodate non-orthogonal layouts of columns all while being able to build at a very rapid pace. Typical post-tensioned concrete slabs follow a three-day construction cycle, i.e., a floor slab is finished every three days. Structural frame on a 40-story tower could be constructed in approximately nine months with careful planning. In addition to the aforementioned benefits, post-tensioning also helps reduce the overall weight of buildings, which reduces the seismic demand imposed on the building’s lateral system and also reduces loads on columns and foundations. Post-tensioned slabs also use less reinforcement and concrete due to the ability of the high strength post-tensioning tendons to compress and push the slab upward to counteract the effects of gravity loading.

This presentation will focus on two projects in Honolulu, The Ritz Carlton Residences and Ae’o, and how post-tensioning can achieve the desires of the client, the vision of the architect and the wishes of the construction team.