Frame Roll Up Structure
As a large platform is built in the yard, frames for each side are fabricated flat in the yard and then simultaneously rolled up into the final position. High capacity strand jacks at several locations incrementally pull the frames from temporary apex structures. Our client had simulated the roll up sequence with a structural analysis program and thus knew the forces on the strand jack link plates for all of the angles.
Apex Structure Detailed Finite Element Analysis
The link plate structure which accomodates the change in angle as the frame rotates into position must be able to resist the maximum load. Since there is no guarantee that the load is always in-line with the axis of the link plate, the load is applied at the maximum off axis angle. The finite element analysis has to incorporate frictional contact between the link plates and the link pins and between the fillet welded cheek plates. Once a solution is obtained at the design ultimate load, the load is increased until the structure fails to determine the ultimate capacity.