Golden 1 Center photo
Once roughly 50 percent of the arena’s frame was erected, the assembly of the building’s 340-ft. (103.6 m)-long roof trusses began.
Both on and off the basketball court, the Sacramento Kings organization is in a state of transition. Internally the organization’s new president of basketball operations bolstered the team’s roster via offseason signings.
Off the court the organization has assembled another team, this one comprised of contractors tasked with building an iconic, new arena for the city’s downtown — the 17,500-seat, $477 million Golden 1 Center.
As fall nears, the project reaches an important milestone, the completion and installation of the arena’s structural steel frame and 340-ft.-long (103.6 m) roof trusses.
To complete these stages of construction — along with demolition and foundation-related work — contractors utilized equipment considered uncommon for downtown Sacramento projects.
“The equipment is perhaps the most interesting thing [about the project],” said Robert Synhorst, project manager of Icon Venue Group, the owner’s representative on the project.
Synhorst cited Liebherr LR 1300 and Liebheer LR 1200 crawler cranes and a Cat 5110b mass excavator as stand out equipment, with the latter playing a large part in the project’s early stages.
To make way for the arena a mall featuring a large Macy’s building, along with a multi-story office building was demolished last summer. The project’s overall footprint accounts for roughly four city blocks.
Responsible for demolition operations was Ferma Corp., a contractor known for recycling at least 95 percent of a project’s construction debris and materials.
The Cat 5110b excavator was equipped with a high reach boom and tore down pieces of various buildings with the help of hydraulic breaker and shear attachments, which can process rebar, concrete and structural steel.
While the excavator worked, a mobile crane held up a large mesh screen used to stop falling debris from reaching nearby streets.
As part of demolition operations, an existing, two-story underground parking garage was removed along with its foundation. Once contractors reached sub-grade they excavated down an additional 10 to 20 ft. (3.3 to 6 m) and hauled that dirt off site.
Prior to driving any piles for the arena’s foundation, significant dewatering of the excavation site had to occur. According to Synhorst, contractors used a system where vacuum-type wells were “dotted” around the perimeter of the area in order to lower the water table.
Malcolm Drilling was then able to commence pile-driving operations, however; because of unstable soil conditions and high ground water the contractor installed roughly 1,000 augercast (cast-in-place) drill piles rather than conventional piles. If Malcolm didn’t use this method, casing or drilling slurry would have been required to stabilize the bore hole.
According to the contractor, these augercast piles can be installed efficiently with modern high-torque hydraulic drilling rigs up to a depth of 115 ft. (35 m) and 48 in. (122 cm) in diameter.
The method utilizes one continuous auger, which is drilled into the ground. The soil on the auger prevents the surrounding ground from caving during the drilling and grouting process.
After reaching pile tip, the auger is extracted while fluid concrete or grout is pumped through the hollow stem auger to fill the hole under positive pressure. Rebar is installed into the completed pile after the auger is removed.
Following installation, the piles were capped with concrete and a two-ft. (.6 m) thick “mat slab” was poured on top. This slab serves as the arena’s main foundation. On top of the slab a two-foot thick section of aggregate base was laid, which created an area to run utility plumbing, Synhorst said, adding the pouring of an 8-in. (20.3 m) thick cap slab followed. This is the slab the basketball court will rest on.
Steel Frames, Trusses
Erection of the arena’s steel frame has been the focus of two Liebherr crawler cranes this entire year. The LR 1300 and the LR 1200 — known for its compact 9.8 ft. (3 m) transport width — have erected steel from the inside out, working in the bowl of the arena. To allow the cranes to escape the bowl, leave-out bays were created on the tight site.
Once roughly 50 percent of the arena’s frame was erected, the assembly of the building’s 340-ft. (103.6 m)-long roof trusses began. However, before this could begin these large trusses had to be transported nearly 50 mi. (80.4 km) by Schuff Steel, the project’s structural steel contractor and truss manufacturer.
Each weighing roughly 270,000 lbs. (122,470 kg) the two trusses were separated into three component sections apiece at Schuff’s production plant in Stockton, Calif.
While two major freeways connect Sacramento to Stockton, these routes could not be used, as they feature overpasses that were too low for the trucks used to transport the trusses. The solution — Schuff’s truck drove country roads into the city flanked by escorts.
“Getting those delivered was a major undertaking,” Synhorst said.
At the project’s site Schuff had to assemble scaffolding/shoring towers to support the truss while it was raised into place, bolted and installed. Workers did not access the towers.
This fall, the exterior façade work will be a focal point. Designed by architectural firm AECOM, the outside of the arena will feature metal glass panels installed in an “in and out” design that resembles diamonds or spikes/pyramids sticking out from the arena. The steel that supports the panels also will have to mimic this in and out form.
Another interesting design aspect of the arena are the large hangar doors that will be incorporated on one side of the building. These doors, which can fold up into themselves, are intended to create an open space on one end of the arena’s bowl, allowing fresh air to enter the arena. No word on if these doors will remain open during games or opposing team’s free throw attempts.
The inside finishes of the arena will mainly be all that remains following façade work, with the project slated for opening of the Kings 2016-2017 season.