Weather has a way of upsetting the best production plans. And for precasters who require a steady production process, losing a few days to bad weather can turn a great job into merely a good one.
Dan Wilmont, a concrete producer who has worked for several large firms in the Milwaukee area, knows this problem only too well. “In our part of the country, we need to plan for 10 of days of production losses due to all types of weather, from sleet to snow, and rain to hail,” he says.
Producers have tried many waterproofing methods to expand production. Yet three constraints have stymied them. Precast concrete elements require great stretches of open space. Their weight requires cranes for lifting. And they must be moved from the casting area to inventory or shipped rather quickly. These constraints make it difficult to find effective temporary structures.
Wilmont brought his production loss problem to Don Kubenik, president of H. Kubenik Mechanical, a steel fabricator in Milwaukee. Together, they developed an innovate solution to a precaster's problem—a portable roof.
Kubenik's engineering team has solved many tough construction problems. His firm has designed and built dust collectors, paint booths, and other heavy-duty enclosures found in some of the toughest applications in the world.
The key is the crane
The ingenuity of Kubenik's design for this temporary enclosure is its reliance on the crane. “Every precast plant has a heavy-duty crane,” says Kubenik. Knowing the maximum lift point and capacity of the industry's most common straddle cranes, his engineers devised a foldable, portable roofing truss broad enough to cover practically every size casting bed that can be set with one pick.
The truss is installed in three stages. First, the 100-foot, center support that becomes the roof's peak is hoisted. This allows the 20-foot top cords, hinged at about 6-foot intervals, to the center support to expand to about a 30-degree angle.
Once the ground is cleared, a hydraulic wench draws up a cable attached to another support, which is connected to a series of bottom cords. The roof is fully extended as the cords become parallel with the ground.
Once extended, the crane then sets the truss on corner supports positioned over the casting area. When installed, the roof's peak is about 25 feet off the ground, allowing about 10 to 12 feet of headroom underneath. The process takes less than 15 minutes.
While the general design is standard, Kubenik plans to custom-build each unit for particular site conditions. In fact, he sees the potential for a smaller version of this roof style for construction sites.
Visit H. Kubenik Mechanical atwww.hkmech.com.