Experimental and numerical investigation of moving loads on hull structures

Regulations and design codes for ships and offshore structures operating in ice infested waters consider only stationary loads for hull structural design. This implies that the effects of movement of a load along the hull are negligible. Real hull structures most often experience operational ice loads in a way that would be better modelled as a moving load. Previous work (Quinton 2008) predicted a significant decrease in the structural capacity of a steel grillage (hull) structure subjected to moving loads that cause plastic damage, when compared with similar stationary loads. In particular, the previous work predicted a decrease in the structural capacity of both hull plating and hull frames. For hull frames, it was noticed that plastic buckling of the frame webs occurred at a much lower load level for moving loads, than for stationary loads. This thesis explores the effects of moving loads causing plastic damage on hull structures using experiments and subsequent numerical models. The results of this work identify a loss of hull structural capacity directly attributable to plastic damage caused by lateral load movement for both plates and frames. It explores the structural response phenomena underlying the observed capacity loses. In particular, this thesis presents: results of laboratory experiments carried out using a novel moving load apparatus involving steel and ice indenters acting on steel plates and frames; a discussion of the design and capabilities of the novel moving load apparatus; a discussion of the structural response phenomena present during moving loads based on a calibrated numerical model of the moving load experiments; and general guidelines for conducting numerical models of moving loads