An experimental investigation into the behaviour of a 5 ton electric overhead travelling crane and its supporting structure
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2007.
In structural engineering practice the actions imposed by overhead travelling cranes onto the supporting structure are defined as static forces amplified by dynamic coefficients and applied as pseudo-static forces without taking the interaction between crane and supporting structure into account. To investigate the validity of this approach, the forces generated at the wheels of an experimental crane are measured, as the crane traverses on the supporting structure. The interaction at the wheels of the crane is also visually recorded. These wheel load results will also be used by other researchers, to calibrate a numerical model of the experimental system. A full-scale 5 ton electric overhead travelling crane (EOTC) running on top of rails and a supporting structure, was designed and erected for research purposes. The crane has a span of 8.3 m and wheel spacing of 4 m, which can be modified. The supporting structure consists of three simply supported mono-symmetric plate girders on each side, with a total length of 13.8 m. This is supported by columns with a height of about 3.5 m. This paper describes the calibration of this system for measurement purposes. A data acquisition system was implemented to capture forces, strains, deflections and accelerations at various points on the crane and the supporting structure as well as to measure the velocity of the crane. The forces at the crane wheels are measured through strain gauges on the end carriage load measuring system. The calibrated facility is used to investigate the behaviour of the crane and the supporting structure under regular and exceptional wheel loads, which are classified as follows: - Regular wheel loads occur during normal payload hoisting and lowering, longitudinal crane travel with payload and lateral crab travel with payload. - Exceptional wheel loads occur during eccentric payload hoisting (payload outside normal operational area), impact forces on end-stops, maximum hoisting of the payload, failure of a longitudinal drive mechanism of the crane, misalignment of the supporting structure and skewing of the crane. The maximum values of these experimentally determined wheel loads and the dynamic response of the system is used to help describe the behaviour of the electric overhead travelling crane and its supporting structure.