Modeling the Beam Deflection of a Gantry Crane under Load

Abstract

Gantry cranes load and unload containers from container ships. To ensure safety and operation, the deflection of their main beams under load should be analyzed. This deflection depends on the weight of the loaded container as well as on the position of the trolley that moves the container. A bivariate polynomial model is build up that estimates the deflection based on these two inputs. This two-dimensional load-dependent model is developed in four steps. It determines the shape of the deflection (dependent on the trolley position) as well as its magnitude (dependent on the container weight). A specific gantry crane was monitored with several sensors: five inclinometer sensors observing the tilt along the crane’s main beam; two tacheometers observing the trolley position and the absolute deflection. Collecting the data of 18 loading operations, the parameters of the deflection model are estimated. Upon this, the deflection under load is processed dependent on the container weight and trolley position. The verification of the whole model shows deviations within +/- 4mm in comparison to an independent loading operation. This quality is acceptable regarding the used measurements.