VPA needed cranes for their Portsmouth Marine Terminal facilities. They purchased three new ZPMC cranes, knowing the PMT wharf had wheel load and other limitations. On the crane side, VPA retained Liftech to work with ZPMC to assist in designing a light-weight truss boom crane for reduced waterside wheel loads. On the wharf side, Liftech reviewed the wharf girders and designed new stowage hardware.
Liftech justified the new crane loading, without requiring VPA to modify the existing wharf, by reviewing the existing wharf using new ACI load factors, assuming reduced dead load factors for as-weighed crane loads, and using more detailed calculation methodologies, such as the strut-and-tie method.
As part of the combined review, Liftech calculated crane tie-down and stowage pin forces and designed new wharf crane stowage hardware to mate with the soon-to-be-delivered new crane stowage systems.
Liftech designed new stowage pin sockets and hurricane tie-down link plates, including design for integration with the existing wharf structure. The new design reduced costs by limiting the amount of field work.
Tie-downs were designed to accommodate crane deflections.
To facilitate handling and tie-down installation, link plates were designed with high-strength steel to reduce weight.
Reference:
Virginia Port Authority
Norfolk, Virginia, USA