For more than a century, people in Norfolk, Va., called a historic downtown building the “Leaning Tower of Granby,” because the nine-story building had a 21-in. northward tilt noticeable from the street. “You could walk up to it and go ‘Hmm, there’s something wrong with that building,’” says Chris Brandt, executive vice president of Hourigan Construction. Brandt’s firm helped correct the decades-old slant at 161 Granby St. and is now busy completing the building’s historic renovation.
A key part of the straightening was a jacking procedure that was successfully executed over four days in December. At ENR MidAtlantic’s press time, the $10.5-million, 100,000-sq-ft renovation remained on budget and on schedule for completion in August.
In addition to challenges associated with straightening the building, the project team was also charged with hardening the building, which is located inside a flood zone. Several concrete flood walls will be encased within existing exterior brick walls, including a 60-in.-high wall to protect ground-floor mechanical systems.
The historic renovation requires replicating certain materials. But rather than trying to match exterior bricks, the project team is installing custom-shaped bricks to replace the bricks that were either missing prior to the jacking process or damaged during it.
Norfolk’s Marathon Development Group purchased the condemned Classical Revival structure in 2016 and resolved to straighten it—a feat that the project team says has never been accomplished on a building that tall. Virginia Beach-based structural engineer Danny Speight was confident that his plan to correct the lean with hydraulic-powered jacks would do the trick. The president of Speight Marshall & Francis had designed the plan for another developer more than a decade earlier, but the effort was thwarted by the recession.
After Marathon contacted him, Speight remembers saying he “wouldn’t lose an hour of sleep” over the job.
Speight’s plan included cutting the building from its foundation before lifting and leveling its 21 columns with jacks. The columns then would be reinforced with concrete. The plan called for jacking the columns inch by inch until the building stood straight again. That meant jacking some columns as much as 12 in. on the leaning side and other columns as little as 1 in. on the opposite side. “It’s a simple concept, but it freaks people out,” Speight says.
The stakes couldn’t have been higher for a project that will yield only 44 apartments and 33,000 sq ft of ground-floor retail when completed. The more than 3,000-ton corner building located in a dense urban neighborhood is four-and-a-half times as heavy as the Eiffel Tower. “It would’ve been catastrophic” if the building toppled, says Matthew Gass, Marathon director of construction. Gass says Marathon’s owner, Frank “Buddy” Gadams, self-funded the $2.7-million jacking because the banks wouldn’t underwrite it.
Hourigan took out $100 million in general-liability insurance, Brandt says, approximately 12 times more than the company typically buys for projects of a similar size. Brandt says, “A lot of people said, ‘You’re going to do what to that building? Are you kidding me? I wouldn’t touch that thing with a 10-foot pole.’”
Completed in 1907, the year of the Jamestown Exposition, the leaning tower was one of Norfolk’s first reinforced-concrete commercial buildings. At its opening, it housed the Hotel Savoy and one of the largest jewelry stores in the South. The building—constructed on a former creek bed filled in with debris from several fires in the early 1900s that leveled the city—is believed to have started to sink slowly about five years later. Many people believe the pilings settled 13 inches into soft spots in the soil. Another theory is that the soil was weakened by pile-driving for a 12-story building constructed across the street in 1912.
In the early 2000s, the deteriorating building was condemned. Three different owners failed to develop it. The city threatened to tear down the tower in 2006 after two pieces of glass fell from it, but municipal officials ultimately required the then-owner only to wrap the building in scaffolding until it could be redeveloped. Another redevelopment effort failed in 2013. Meanwhile, inspections continued to determine that the building was structurally sound.
Gass, whose office is located about 200 ft from the tower, always considered it “an eyesore” that Marathon had no intention of buying. But after renovating 15 other properties in the vicinity in the last five years, Marathon concluded that acquiring and straightening 161 Granby was a sound business decision, no matter the cost. Gass says, “We realized if we want to make our product look good from all directions we have to fix this thing.”
State and federal historic tax credits helped make the project feasible. Brandt says they accounted for approximately 25% of the total renovation cost. He says tearing down the building would have cost about $1 million. Gass says Marathon was committed to straightening the building regardless of the risk.
Speight was originally contacted about the project in 2003. The owner at the time showed him reports from other structural engineers suggesting that the best way to straighten the building was to fix its foundation, which would have involved driving piles into busy Granby Street and City Hall Avenue. Speight believed that was unnecessary because the foundation was stable and the lean hadn’t worsened in almost a century.
Inspections conducted at the time Marathon bought the building concurred. When Marathon said, “It’s not stable, it’s leaning,” Speight replied, “Well, it’s stably leaning.”
Hourigan, the project’s construction manager, was having such a difficult time assembling a team of firms willing to take the job that Speight drafted a letter certifying that it was safe to work there. “It felt a little precarious, but that thing had been standing for more than 100 years,” says Paul Keller, an architect at Tymoff + Moss.
Keller spent two months taking detailed measurements of the building, including the cockeyed elevator shaft that had to be completely rebuilt. “There are no right angles, so it took a while to document and get everything right,” Keller says.
Speight’s plans had strict sequencing that required Hourigan to call his team in to personally review each completed step. “I’ve never seen a more structured sequence of events on the structure of a building as I’ve seen on this one,” Brandt says.
The team began by installing a horizontal structural steel frame on the first floor to prevent the building from racking during the jacking process. The frame, installed 15 ft above the slab on grade, connected all 21 columns across the 7,000-sq-ft first floor.
Below that new frame, steel clamping frames, or collars, were fastened to each column with high-flow grout. The collars were placed on the upper and lower portions of each 24-in. by 24-in. interior column and 36-in. by 36-in. exterior column.
The team placed up to eight 200,000-lb jacks on the columns between the collars. The 8-in.-dia. custom-made jacks cost $2,500 each. A hydraulic manifold supplied pressurized hydraulic fluid from a pump to the jacks to transfer the entire building load to the columns and into the jacking system.
Crews then used chainsaws to cut about a foot out of each column between the collars, including the reinforcing steel. That freed the building from the foundation, placing the building’s entire load on the jacks until the crew was ready to jack the building level, about 18 days later.
Once the building was leveled, the jacks were locked. Concrete columns were repoured, entombing the lower collars. After the concrete cured, the team removed the jacks and upper collars and began the historic renovation phase.
Simple in theory, the jacking concept’s details were too difficult to explain to contractors in traditional plans. Speight developed a separate set of drawings for each step of the process—nearly 70 sheets in all. He had help from Rudi Van Leeuwen of Fredericksburg, Va., a Dutch structural engineer and brace excavation and deep-foundation specialist. Van Leeuwen had extensive experience working on reclaimed land similar to Norfolk’s. “Being Dutch, that’s what they do, they take land from the ocean and live on it,” Speight says of Van Leeuwen, who came out of retirement when the project was revived in 2016.
Before implementing the plan, however, Speight met with the entire project team, including structural movers Nicholas Bros. Inc. The fifth-generation, family-owned business based in Hopewell Junction, N.Y., has specialized in transporting buildings and other structures since the late 1800s.
Speight asked the team if there was another way to carry out the job. He says subcontractors had valuable suggestions, but the plan’s core scheme remained intact.
Before the team straightened the 3,250-ton building, they lightened its load by as much as 375 tons, first by removing non-load-bearing walls, heavy plasterwork and existing steel framing. Historic masonry walls also were removed from the first two floors so the jacking structure could be installed on the columns. “It’s very difficult to remove brick that is that old carefully enough and without damaging it,” Keller says. The brick and terra-cotta trims were stored and will be cleaned and, eventually, reinstalled.
The team demolished several concrete topping slabs poured after the building had leaned in an effort to level the floors for office workers who occupied the building before it was condemned. The team also installed masonry shoring angles and beams in preparation for the jacking as well as lateral and X-bracing steel beams to stabilize concrete columns on the mezzanine level, which is 17 ft above the first floor.
Even though team members were confident that the building had settled, they stabilized the foundation, including pile caps and grade beams, with 122 spiral helical piles. The spiral piles were screwed up to 65 ft deep and connected to existing piles with epoxy and dowels.
Working without the original drawings, the team removed the slab on grade only to discover that timber piles were spaced “closer than we’d ever seen in our lives,” Speight recalls. Strengthening this “forest” of piles was complicated by the existing foundation’s inconsistent depths. Speight accompanied a worker into a crawl space under the slab on grade to help determine where the spiral piles could be screwed. The worker was “struggling there for a little bit,” Speight says, “but we got him going.”
Because of the foundation’s poor condition, the team spent about a month installing the helical piles. On the whole, preconstruction—including demolition, preparing the building for jacking and constructing the temporary foundation system to support the building before jacks could be engaged—took five months longer than planned, Gass says.
Given that delay, Hourigan decided to accelerate the schedule by performing some interior work out of sequence. For example, the team installed metal stud framing while the building was still leaning. The team erected the studs “a little out of plumb so that when the building straightened up the studs were plumb,” Brandt says.
Installing the studs early might not have been necessary because the jacking procedure went so smoothly. The team expected the process to consume as much as a month, but it only took four days. The task “was over before we could even get excited about it,” Gass says. “It was almost anticlimactic.”
In December, the project team was finally ready to energize the jacks and lift the building. On Dec. 12, workers cautiously raised the jacks an inch or so. Then they spent about 20 minutes surveying the building and inspecting for cracks and other potential damage. Using this approach for a full day, the team lifted enough to reduce the 13-in. settlement by 7-½ in., the maximum amount the jacks would allow in one session. The team locked the jacks and spent the next two days resetting them to lift it up the rest of the way.
On the fourth day, the building’s movement could be seen with the naked eye. “The physical jacking part was done in about a day and a half,” says Speight, who notes that there was no cracking in any columns or beams. The masonry mostly remained intact, too.
The process wasn’t flawless, however. About two hours after workers started lifting the first column on the first day of jacking, two other columns lifted vertically off the jacks by 2 or 3 in. Speight wasn’t troubled that the unsupported columns held a collective 400,000-lb load. “This building had already redistributed its loads the way it was framed so these columns could basically get blown out and the whole building would stand up,” Speight says.
Even so, several team members were nervous and wanted to shim the columns back onto the jacks. Speight told them that was unwise. “A building has a personality,” he says. “Most engineers, they don’t figure out how the building wants to act, they just kind of say, ‘Well this is the way I’m going to make it act,’ which in concrete doesn’t work.”
As the team continued jacking the next series of columns, one hanging column settled back onto its jacks while the other still hung. It didn’t return to its jacks, so Speight, after about six hours, decided to shim it back into place.
That snafu aside, Speight knew the procedure would work after two-thirds of the jacking was completed after only one day. He went home to celebrate with a bottle of Champagne. “I’m not trying to sound cocky,” he says, “but I just knew it was going to work.”
But Speight didn’t uncork a second bottle. There was still another day of jacking ahead.