Megacranes: Holding Sway—Boom Motions

by Erik Soderberg

Over time, vessel size and container weights have increased. While the size, mass, and strength of the crane structure have also increased, the stiffness of the crane structure has not increased proportionally. The crane response to trolley and gantry accelerations has changed.

Several years ago, operators reported undesirable crane deflections in the trolley travel direction during operation. Liftech responded by developing crane stiffness requirements in the trolley travel direction to limit the crane deflection, and the problem was solved.

Within the last year, a similar problem has emerged. Some operators reported unacceptable boom vibration in the gantry travel direction.

This paper discusses the factors affecting lateral boom vibration, what vibrations are acceptable, and provides recommendations to reduce lateral boom vibrations.