Engineering and Experience Help DPR Push the Envelope on Successful Four-Story Tilt-Up Project for BTV Crown Equities in Sacramento

Pushing the limits of technology with the aid of careful study, innovative engineering and an experienced field crew, DPR has successfully completed the erection of 22 concrete tilt-up panels on an unusual four-story tilt-up commercial office building for BTV Crown Equities in Sacramento.

The groundbreaking project represents just the second time that tilt-up construction has been used on a four-story, mid-rise building in the region, according to project manager John Taylor. Traditionally, tilt-up construction has been limited to one- to three-story structures due to economic and engineering factors. However, when DPR compared it to five different structural systems for this fourth project on BTV Crown Equities’ five-building corporate campus, tilt-up was found to offer the greatest cost and noise reduction benefits. The latter was a key consideration, given the project’s close proximity to two major freeways, I-80 and I-5.

“This was determined to be the most cost-effective way to mitigate the freeway noise,” Taylor notes. The sheer mass of the concrete panels, along with extensive amounts of insulated glass that form the building’s skin, helps dampen the noise from nearby freeway traffic.

Ron Russell, president of BTV Crown Equities, added that facility owners also prefer the clean floor plates that a tilt-up offers over steel-frame structures, especially when it is more cost efficient. “The concrete not only absorbs much more of the sound but also enabled BTV to save additional dollars on the overall cost of glazing that’s required for a steel-framed building.”

“I would not have been able to make the decision without the preconstruction estimating that DPR is just outstanding at providing,” said Russell. “The solid data that DPR presented allowed me to really analyze all of the components of a steel frame versus tilt-up and make an intelligent choice. It was the best preconstruction estimating that I’ve ever seen at a construction company—bar none—and it’s a pleasure to be able to say that.”

DPR worked closely with structural engineer Culp and Tanner, Chico, who pushed the engineering envelope to design panels that resisted bowing when picked up by the massive 300-ton crawler crane brought in to hoist them into place. The crane itself was delivered on 12 flatbed trailers and assembled on site with the aid of another crane, prior to the tilt-up installation that took place at the end of October 2002.

The project entailed erection and placement of 22 total concrete panels, averaging 14-in. thick, 30-ft. wide, 59-ft., 6-in. tall and 72.5 tons. Four 530-pound braces were used on each panel for support, and the crawler crane with its 142 feet of boom was used to pick the panels and put them in place.

A crew of 12 carpenters and laborers, three iron workers and the crane operator and oiler were on-site for the tilt-up operation. Originally scheduled to take three full days, the project team was able to complete the panel erection in just a day-and-a-half, a feat Taylor attributes to the effectiveness of the crane and its operator, an experienced field crew, good weather and plenty of preplanning. “It was absolutely amazing that we were able to complete this process in just a day-and-a-half,” he comments. “We had a knowledgeable crew and the right infrastructure in place to get it done quickly. Culp and Tanner also did a great job engineering these panels, so they could be picked and set into place without any problems. That’s a huge credit to them.”

The 126,000-sq.-ft. office building, designed by LPA Sacramento, Inc. features an architectural accent wall that runs through its axis, highlighted by a ribbon of slate imported from India. The lobby area features a wainscoting of the slate running up two framed stucco walls to the roof area on both the back and front sides. The building’s design is similar to that of the three existing buildings on the campus, which range from 63,000 to 92,000 sq. ft. and two to three stories. DPR also constructed them using the tilt-up process.

A sign of the cooperative and proactive approach DPR has developed with the owner, crews pushed ahead with foundation construction in the summer of 2001, several months earlier than planned, in an effort to avoid potential weather delays from performing that work in the winter. That move paid off once the project officially got underway. Early foundation work, combined with successful panel installation and relatively dry weather as of early December, had the project running slightly ahead of schedule. DPR is slated to complete the job in July 2003 and will construct the fifth and final building on the campus sometime in the future.

“It was the best preconstruction estimating that I’ve ever seen at a construction company—bar none—and it’s a pleasure to be able to say that.”
- Ron Russell, president of BTV Crown Equities