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PREFABRICATION | STRUCTURAL STEEL DECK PANELS

Posted By Mike LaRue On January 20, 2015

A few of the latest projects the JP Cullen team has been leading are structural steel erection projects in the Madison area, which involved the use of prefabrication on the jobsite. Due to some unavoidable challenges early on in the foundation portion of the project, the team knew they had to make a comeback to keep the project on schedule.

The use of steel prefabrication was the answer as the 228K SQFT project was brought back on track, allowing the team to not only get back to the intended schedule, but actually gain on the timeline. Prefabrication is not commonly utilized in the construction industry, mainly due to resistance to change in combination with an initial upfront investment by the company to develop the process. After the process is developed, as JP Cullen has successfully accomplished, a client can expect to see the project schedule bound ahead along with an increase in quality of the craftsmanship due to a majority of the work being done in a controlled environment versus at the face of the work.

A major portion of the prefabrication process for these projects involved the iron workers, who had the opportunity to sequence out the delivery of their structural steel to the jobsite. This sequencing allows the team to make sure pieces arrive in the order being built to the project, which in turn avoids the crew being inefficient and searching for their needed pieces by the industry standard truckload delivery. When a project requires over 255 tons of steel, it’s crucial to plan ahead and sequence the work to stay on schedule.

Below shows an example of how many steel components went into each building:

BUILDING STEEL COMPOSITION:
• Building 1:
o 210 pieces structural steel
o 616 bolts (detailing)
o 5,298 shear studs
o 27,000 SF metal decking

• Building 2:
o 201 pieces structural steel
o 644 bolts (detailing)
o 4,511 shear studs
o 24,000 SF metal decking

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The team purchased column tops and set up a test fixture. After a couple of trials they developed a plan and process to prefabricate the structural steel panels on the ground. A special concrete fixture was built for each building to fit the specs of the 85 total panels that could be built at ground level. The ground level fixture squared the panels as they were built, naturally forcing the columns to be plumb.  This ensured a quality building without the need to plumb each column separately.  The time needed to plumb each column was effectively taken away from the building, freeing up more time to set panels.

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Prefabricating the structural steel panels allowed the team to fly several pieces of steel into the building all at once, leading to huge schedule savings, 4 weeks per building, in a time critical portion of the building process. Due to this process, the panels were more complete when they were installed compared to a traditional build. The metal decking, shear studs and even the receivers for perimeter fall protection posts were attached while the panels were on the fixture. Not only did it save time on these activities later in the process, but it was safer to detail the panels on the ground.

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Safety is a major factor during every building project – especially during the steel erection phase. The team reduced their exposure to fall hazard by 16% by working off of the custom ground fixture, which was less than 6 feet off of the ground versus what would have been 44 feet above ground. Workspace congestion was decreased and efficiency increased as fall protection gear was not required at this height, which reduced fatigue and increased productivity. With all tradespeople working on the ground versus above, only a few lifts were needed on site which further reduced congestion. An additional benefit to working from ground level is the ability to double check the quality of work. It makes quality control a lot more measurable when you’re on the ground versus over 40 feet in the air.

An additional challenge facing the project team during this time frame was the shortage of ironworkers available for the site. Due to the prefabrication of the steel on the ground, the team was able to meet and pull ahead of the intended schedule with fewer workers than a typical project of this magnitude. Normally the process would have been to set the columns, then set one or two pieces of the beams at a time. This new process allowed a simultaneous build of the building with fewer people – in a more proficient manner. By prefabricating structural steel panels, the iron workers onsite reduced the work done at the building itself, increased safety and productivity, and balanced manpower more efficiently.

JP Cullen has continued to incorporate prefabrication into many other phases and areas of work onsite due to the success of these projects. If you have any questions relating to prefabrication or to see if this approach may be incorporated into any upcoming projects for your company please feel free to reach out to Mike LaRue, Prefabrication Manager at JP Cullen.

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