Global risk services firm Applied Underwriters is relocating their corporate headquarters to the heart of Nebraska. The headquarters campus encompasses 50 acres and is the anchor project of Omaha’s 500-acre Heartwood Preserve—one of the largest urban developments in the United States. Ceco Concrete is providing 568,000 square feet of elevated concrete deck formwork for the three-story, 260,000-square-foot office building, which includes a two-level garage underneath.
The project consists of two concrete levels below grade and three levels of structural steel above for the offices. A portion of the garage is topped by two office wings joined by an 80-foot-tall atrium, while the rest of the garage is covered by a green roof. Ceco is using reinforced concrete structural systems to provide the best support for the building’s structural steel frame and exterior skin loads, as well as for the green space planned for the garage roof.
Supporting office loads
The Ceco team started with the office-supporting portion of the garage before dropping back down to construct the portion to be topped by a green roof. The office portion was separated into three wings: east, west and atrium (middle).
Using Ceco-owned HV formwork with drophead panels, the crew started Basement Level 1 first, installing 10- and 12-inch-thick mildly reinforced slabs with drop beams. Basement Level 1 consisted of 15 pours, with each pour covering approximately 10,000 square feet. They then moved up to Level 1, pouring the east wing and then the west wing to construct 12- and 14-inch-thick mildly reinforced slabs with drop beams.
This sequence of work allowed office-level structural steel erection to begin on the east wing and roll right into the west wing. At one point, Ceco was framing and decking three levels simultaneously.
The atrium was the last section to be built at Level 1, and it was the most challenging. A majority of the work was performed at exceptional heights and the beam depths varied, ranging from 24 to 71 inches. The Ceco team used a combination of HV formwork, Ceco-owned purlins and runners for the beam bottoms, and Titan shores for high work throughout the project.
A “stair-step” sequence
After completing three of six atrium pours at the office portion of Level 1, Ceco’s crew dropped down to Basement Level 1 to start framing the remaining garage space. Once four deck pours were placed at that level (to install 10-inch-thick mildly reinforced flat-plate slabs), the crew started framing Level 1 to construct 14-inch-thick mildly reinforced slabs with drop beams. This “stair-step” process is being used throughout the garage construction.
Pour layouts and footages are similar to the office portion’s Level 1, with the exception being that the garage is not broken into wings. The general contractor is averaging one pour per week.
Stops and starts
The project began January 2020 and was shut down twice due to the COVID-19 pandemic. The first shutdown occurred in late April 2020 and lasted approximately six weeks. During the second shutdown, which began September 2020, the Ceco team had formwork with rebar in place for nine months as they waited for work to resume.
The Ceco team is now on schedule to complete work March 2022.