MODEL TESTS ON VARIOUS LAUNCHING METHODS FOR LARGE OFFSHORE STRUCTURES

As offshore structures become larger and heavier, launching barges are being used to transport them. The conventional method of launching offshore structures at the job site consists of pulling or pushing the structure in the longitudinal direction of the barge using jacks and/or winches. This requires an extremely large launching capacity, and thus large-scale jacks and other units. In addition, excessive stresses tend to be produced in the barge hull. With a view to finding a way to launch large structures without these problems, we conducted model tests on site launching -- a method whereby the structure is launched sideways in a direction transverse to the barge. A twin-barge installation method has been proposed by J.B. Graham, et. al. In this paper, we propose two other launching methods based on twin-barge installation. In all, we conducted model tests on five different launching methods. Our paper will present the results of those tests, and discuss the practicability of the different launching methods as evaluated by analytical methods, including computer programs.