THE CHALLENGE:
This particular customer was consolidating two independent operations at one new location. This customer’s company manufactures large pressure vessels and process equipment. Their final product is usually very heavy, long, and bulky. The largest units to be handled approached 40 tons in total weight. Because the heaviest loads were long and had to be lifted at each end, two cranes would have to work together, distributing the loads on the crane-ways and support structure.
THE PROBLEMS:
Limited Budget – Customer wants used cranes to minimize investment. After considering all the other parameters that we would have to satisfy, we agreed that new equipment would provide the needed flexibility to provide the best value and return on investment.
Leased Building – the building had limited vertical clearances, and we can’t use the building structure to support or stabilize our crane system.
Long Unsupported Craneway Intervals – Existing building columns at 40 ft. intervals along craneway. Customer wants crane structure supports to be at 40 ft. intervals to created a 20 ft interval between building column and craneway column, and he does not want structural bracing obstructing traffic or material flow in the work area. Customer demands maximum lift and floor clearance under new 10 ton and 20 ton cranes.
THE SOLUTION:
In order to avoid placing any stress on the building itself while keeping costs to a minimum, we designed a system with three parallel craneways that shared common columns along the interior. To minimize the amount of headroom used we designed large footings with cantilever or “lolly-pop” columns designed to tolerate vertical and lateral loads with minimum deflection. We were able to locate some salvaged craneway beams, which helped us to minimize costs and stay within budget, allowing for the purchase of more new cranes than what was originally planned.
A large part of this job depended upon the design of the footings. Because of time constraints, we had to estimate the footing sizes without the benefit of a soils report. After we presented our proposal, we learned that the existing soil was far below average strength and we would need larger footings.
Despite a tight construction schedule, and a customer with a tight budget, we were able to complete this job on time and on budget while providing a high quality finished product.
THE EXPERIENCE:
We wanted to do this job because it represented a significant challenge. Because of the need to complete the project in as short a time as possible, we frequently had to coordinate our effort with other trades. We had to make a significant change in the middle of a project, and with the help of a good footing contractor, we accepted the challenge and proceeded with satisfying this requirement. And in the end, we learned that Facilities Engineering can offer the complete package to a customer from design to finish no matter the size of the project.