L.A. Live Tower Structure Hailed at Steel Industry Event

DOWNTOWN LOS ANGELES — For the design of the seismic support system inside L.A. Live's 54-story hotel and condo tower, Nabih Youssef looked to a place one might not suspect. "It all comes from battleship engineering," he told the crowd today at a well-attended event put on by the American Institute of Steel Construction (AISC).

Youssef, president of structural engineering firm Nabih Youssef Associates, was speaking of the choice to use steel-plate sheer walls to provide the tower's strength.

While the term might mean little to those outside the construction industry, the benefits to the project are easy to understand. Weight of the building was reduced 30%, window-space was increased, and 3-4 months were taken off the project's timeline.

The L.A. Live tower is the first building in Los Angeles to be erected using this method of support. For Nabih Youssef Associates, that meant doing some intense modeling to show that their design was sound. Engineer Ryan Wilkerson told the construction industry crowd that the computer model used for testing had 30,000 elements and would take seven days to run.

Typical high-rise construction uses thick concrete sheer walls to provide lateral strength. These walls range from 24 to 36 inches thick. Steel-plate sheer walls are just 1/4 to 1 inch thick, and new techniques allow the plates to provide improved performance over the thicker design. The steel dissipates seismic energy throughout the entire structure, rather than just at the foundation.

For the L.A. Live condos, that change in supporting wall thickness meant an extra 776 square feet in sellable space per floor. With 26 floors of condos, that adds up to just over 20,000 extra square feet. At prices over $1,000 per square foot, that's an extra $20 million in condos for AEG to put on the market.

The reduced weight of the steel plates compared to poured concrete walls meant that less foundation work was required, cutting time and cost off of the project. Additional time savings were realized through the lack of a need for time for poured concrete to set before moving higher.

The tower now stands at 46-stories, and is due to be topped off in December, two months ahead of schedule. Total budget stands around $1 billion.

Herrick Steel and AISC sponsored the morning event. Webcor Builders is the contractor on the tower, which was designed by architecture firm Gensler.