Pitting corrosion is typical corrosion observed on coated hold frames of bulk carriers which exclusively carry coal and iron ore. In order to secure the safety of these types of bulk carriers, it is important to understand the effect of pitting corrosion on local strength of hold frames.
In order to investigate this effect, a series of 4- and 3-point bend tests on structural models which consist of web, shell and face plates has been carried out. Artificial pitting was created on the web plate to simulate pitting. In the 4-point bend tests, two equal concentrated loads have been applied vertically at the one-third points of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, lateral-distortional buckling occurred before reaching the ultimate strength and local buckling of the face plate was observed after reaching the ultimate strength. The effect of web plate pitting on the lateral-distortional buckling strength was found to be small but the ultimate strength decreases with increase in the degree of pitting intensity. In the 3-point bend tests, concentrated load has been applied vertically at the center of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, local face buckling occurred just after reaching the ultimate strength. The ultimate strength is found to be decreasing with increase in the degree of pitting intensity.
A series of non-linear FE analyses has been performed to simulate the deformation behavior observed in the tests. It has been revealed that even in the case of randomly distributed pitting corrosion the ultimate strength of the structural models was almost the same as that of the structural models with uniform corrosion corresponding to the average thickness loss. 相似文献
The deregulation of the British bus sector (outside London) in 1986 was the start of a debate on the merits of ‘deregulation’ and ‘competitive tendering’. The period that followed was rich in lessons. New Zealand was at the time the only other country engaging in a reform based upon market initiative (implemented in 1991). Other countries chose for a less extreme and more consensual way to introduce competitive incentives, choosing the fundamentally different competitive tendering (CT) path. As a result, the so-called ‘Scandinavian model’ developed, based upon the London example of route tendering. Later the Netherlands adopted a network tendering approach, resembling the French practice of network tendering though with more operator freedom. 相似文献
The past emphasis in this conference series has been on the best ways to deregulate regulated public transport markets. This workshop reverses this process by examining the best ways to regulate deregulated public transport markets. A hierarchy of regulatory needs is identified and three hybrid models examined, based loosely on experience from Great Britain, New Zealand and Sweden. It is argued that deregulated public transport markets are a global phenomenon but regulatory measures should reflect local requirements. The resultant process of glocalisation might result in regulatory measures that focus on the rules of law and their enforcement in emerging public transport markets (such as urban transport in Sub Saharan Africa and for the soon to be competitive inter urban market in Germany) but that focus on guidance for network integration and incentivisation for welfare maximisation in more mature public transport markets (as in Great Britain, New Zealand and Sweden). 相似文献