Wonderful Engineering

This New 38-Story Tower In Seattle Will Be Supported By Just 20 Columns

A unique skyscraper will soon be constructed in Seattle which has never been constructed before in the world. A 38-story tower will soon be sitting a full 85 feet off the ground and will create a complete open plaza space under it. This will be done by using the immense strength of 20 steel and concrete columns that will support it. The Skanska USA 2+U project is designed by architectural firm Pickard Chilton and will give Seattle a new office space. The open-air 24000 square foot retail, arts, and cultural plaza is the main thing here. There are 20 huge columns which will hold the tower and create space for its own two and three-story buildings.

The lifted tower will provide between 65 and 85 feet of usable space below it. The composite columns which are engineered by MKA and weigh between 69000 and 165400 provide the required structural support. The columns arrived at the job site at night. Murphy McCullough, executive vice president of Skanska USA said, “There was only one route we could figure to get those columns to the site because the trucks and trailers were so large and heavy. We hired a logistical engineer just to figure out how to get the things to the site with clearances and turning radiuses and how we were going to pick them (with a crane). It was an extremely intense experience.”

To lift the columns two 500-ton cranes were required. Each column was then placed in the foundational Y support which was bolted and welded into place. Each of the two-column Y design matched with another to form a huge W across the base of the tower. This created aesthetic and functional space under the tower. After the installation of all the towers, they were filled with concrete and fitted with additional rebar to create strength which will hold the tower above.

The collaboration between Skanska, Pickard Chilton and MKA made sure both the functional component of the column design and also an architectural flair. McCullough said, “How do you create columns to hold up the building and be sculptural that took a long time to figure out.” He added, “The sight slopes, so we really wanted the experience to have a height and grand scale. We really wanted to make sure we could have this village down below the office building. If the office building was too low, it just wouldn’t have worked. It needed to have enough light and air through it to feel like a separate special urban village.”

The columns have all taken the position and allowed the office building which starts at level seven. By the end of 2018, Skanska is expected to finish the concrete and steel work and will have the entire project ready in July 2019. McCullough said, “The big reason for doing this was from a pure customer standpoint. If you have a very special building with an amenity base employees really want, you are much more apt to attract (labour) talent.”