Sitting inside the overall footprint of the future Carlsbad Performing Arts Center, Alliance Riggers’ Liebherr LR 1750 lattice-boom crawler crane sets the stage area’ s 79-foot-tall concrete wall panels, which weighed up to 225,000 pounds with rigging.
the construction would take place during the school year.
That meant work had to stop when classes changed during the day, heavy lifts would be made when nearby classrooms were empty, and steel would be hung during off hours when possible. But the biggest challenge in constructing the 79,000-square-foot, 1,100- seat facility would be working on an extremely tight site to tilt up cast-on-site concrete panels that stood up to 79 feet tall, measured 8 to 22 feet wide, were 8 inches thick, and weighed up to 225,000 pounds with rigging.
Owned by Carlsbad Municipal Schools, the new performing arts center sits between three other buildings on the Carlsbad High School grounds, and stands just 15 feet from one of them.
As a result, Alliance needed to find a way to tilt up and place the precast panels using one crane that sat inside the building’ s footprint and was surrounded by casting beds, many of them also within that footprint.
“ This is the most difficult panel layout we’ ve done,” said Anthony Oritz, Alliance’ s operations manager.“ We held a pre-lift meeting for each panel just to make sure everything was right.”
Planning and Good Communication Prove Vital
A major key to the project’ s success was meticulous planning and frequent, clear communication between Alliance; general contractor Jaynes Corporation, which also cast the concrete panels; the project owner, the architect, the engineer of record and the steel fabricator.
Alliance actually began its planning by using AutoCad and 3D Lift Plan as it bid the job in 2022, more than a year before the physical work started.
“ You can’ t even bid a job this complex without having a solid plan,” said Alliance co-owner and CEO Phil Cordova.
As Alliance developed the panel-erection layout plan in AutoCad and 3D Lift Plan, the information could be transferred into Jaynes’ building information management( BIM) system so that everyone stayed on the same page.
As the precise planning progressed, cooperation between the team members made the project more workable.
The key piece of equipment was Alliance’ s LR 1750 latticeboom crawler crane, which would be uprighting, lifting and setting the concrete wall panels.
“ There aren’ t many big cranes in this area, and our LR 1750 was the best solution to lifting nearly all of the panels from inside the building,” said Cordova.
He noted, however, that some of the panels plus rigging would be heavier than the crane could pick at the radius needed.
Working together, Alliance, Jaynes, the architect and the engineer of record made some of the panels narrower in order to keep the weight within a safe percentage of the crane’ s capacity.
In addition, Jaynes worked with Alliance to make sure each panel was cast in an orientation for proper tilt-up.
“ We could tell them that the top of a panel needed to face
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