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In Utah, Historic Facade Saved with Stilts
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Exterior rendering of Utah's historic, brick facaded Provo Tabernacle
The 6.8-million lb brick facade of Utah’s historic Provo Tabernacle, originally constructed between 1883 and 1898, is currently sitting on a series of needle beams that rest upon 9 in. diameter, 40 ft tall stilts as the new Provo City Center Temple is built beneath—and within—it. The Church of Jesus Christ of Latter-Day Saints

The brick façade of the Provo Tabernacle, originally constructed between 1883 and 1898, is currently sitting on stilts as the new Provo City Center Temple is built beneath and within it.

June 18, 2013—When fire destroyed the interior and roof of Utah’s historic Provo Tabernacle in December 2010, the church community that used the building was devastated. Leadership within The Church of Jesus Christ of Latter-Day Saints decided that rather than raze the brick façade that survived the fire they would instead reuse it as part of a new 85,000 sq ft Provo City Center Temple that would be constructed on the site. The 6.8 million lb brick façade of the tabernacle, originally constructed between 1883 and 1898, is currently resting on 40 ft tall stilts as the new Provo City Center Temple is built beneath—and within—it.

The facade is being preserved because of the value church members have held in the building as a place for meetings and cultural events, and as a tangible statement of belief. The building “symbolizes the dedication of the pioneer settlers of Utah Valley and their dedication to God and their community,” said Andy Kirby, P.E., a senior project manager within the church’s special projects division, which is responsible for the project, who wrote in response to written questions submitted by Civil Engineering online. “It will also serve as a beautiful temple exterior,” he noted.

The goal of the project was to keep the facade firmly, and carefully, in place. Getting to that point was tricky: the five-layer-deep masonry facade could not stand alone after the fire—it was supported by exterior braces—and a two-story basement needed to be added underneath it, according to Kirby. Once construction began on the new temple project in 2012, preparatory work to ensure that the facade could stand on its own began. 

Image of a fire which destroyed the interior and roof of the Provo Tabernacle in December 2010

A fire destroyed the interior and roof of the Provo Tabernacle in
December 2010. Leadership within the Church of Jesus Christ of
Latter-day Saints decided that rather than tear down the brick
façade that survived the fire they would instead reuse it to create
the new Provo City Center Temple. The Church of Jesus Christ
of Latter-Day Saints

The first step was to remove the two innermost wythes of brick from the facade, Kirby explained. Steel helical ties were spaced 18 in. apart on center in each direction on the interior of the facade and then covered with a thin layer of shotcrete to create a reinforced concrete wall. Once this was done, the exterior shoring and bracing was removed and the facade could officially stand on its own.

The next major step included underpinning and shoring the historic masonry in preparation for the 40 ft excavation that needed to take place for the new basement. Shoring piles—146 of them, each 9 in. in diameter—were placed inside and outside the historic walls. The piles had steel casings that were installed to a depth of 60 ft, but the piles themselves extend to a depth of 90 ft. Needle beams were then inserted through the façade’s foundation and bearing haunches that had been built into the new reinforced concrete layer of the facade’s interior, according to Kirby.

Once the needle beams were in place they were welded to the shoring piles and a pancake jack was used to engage the facade onto the shoring pile system, he said. The entire shoring and underpinning system was shimmed and welded again after the 6.8 million lb load was transferred to the shoring pile system.

It was at this point that excavation under the facade began. Once the area around and under the facade was excavated to a 20 ft depth, cross bracing was added to the shoring piles, Kirby said. A 45 ft deep cutoff wall was placed around the perimeter of the lower portion of the excavation, and interior dewatering wells were placed. Once the site was dewatered, the remaining 20 ft depth was excavated and the shoring piles were again braced. The remainder of the depth was then shored and excavated.  

“Our directive is to preserve [the facade],” said Kirby. “This solution gave us the best final product, the best schedule, and the best cost while preserving the structure.”

Exterior image of the Provo Tabernacle as pictured in 2009

Pictured here in 2009, the Provo Tabernacle facade is being
preserved because of the value church members had for the
building as a place for meetings and cultural events, and as a
tangible statement of belief. The new temple—a building reserved
for church members—is expected to be complete in 2015.
The Church of Jesus Christ of Latter-Day Saints

The new basement will rest on an 18 in. thick reinforced-concrete slab located atop 411 micropiles, Kirby said. The 24 in. thick reinforced-concrete foundation walls will be built up between the shoring piles. Once the top section of the new foundation is engaged with the masonry facade, the contractor will remove the shoring piles. The structural systems for the new temple’s interior and roof will be of steel columns and beams, with composite decks. A steel beam-supported roof and center tower will be used.

“You see the final solution now, but the process or path to get there was a great challenge,” Kirby said.

A top-notch design and construction team was the key to the successful concept and design, according to Kirby. The team, the majority of whom are located in Salt Lake City, includes architecture firm FFKR Architects; structural engineering firm Reaveley Engineering; Provo, Utah-based geotechnical engineers RB&G Engineering and GSH Geotechnical; civil engineers and hydrogeologist Bowen Collins & Associates; the shoring subcontractor Nicholson Construction; and general contractor Jacobsen Construction.

The new Provo City Center Temple is expected to be complete in 2015. The church has made a live feed of the construction progress available online.


 

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