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This paper introduces a novel analytical method to predict the buckling collapse behaviour of a ship hull girder subjected to several cycles of extreme load. This follows the general principles of the established simplified progressive collapse method with an extended capability to re-formulate the load-shortening curve of structural components to account for cyclic degradation. The method provides a framework for assessing residual hull girder strength following a complex series of unusually extreme load events where the wave induced bending moment rises close to, or even surpasses, the monotonic ultimate strength. These load events may be sequential, such as might be caused by a series of storm waves, or they may occur as a collection of discrete events occurring over a longer period. The extreme cyclic bending amplifies the distortion and residual stress initially induced by fabrication in the flanges of the girder, which results in a deterioration of the residual ultimate strength. Validation is firstly completed through a comparison with previously published experimental work and secondly via comparison with numerical simulation on four ship-type box girders using the nonlinear finite element method. 相似文献
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Wave energy assessments in the Black Sea 总被引:1,自引:0,他引:1
Eugen Rusu 《Journal of Marine Science and Technology》2009,14(3):359-372
The present work aims to evaluate the wave energy resources in the Black Sea basin. The study is focused on the western part
of the sea, which is traditionally considered as being more energetic. In order to give a first perspective of the wave climate,
a medium-term wave analysis was carried out using in situ measured data. As a further step, a wave prediction system was implemented
for the Black Sea. This was based on the simulating waves near-shore model, which is used for both wave generation and near-shore
transformation. This methodology has the advantage that a single model covers the full scale of the modelling process. Various
tests were performed considering data measured at three different locations. Special attention was paid to the whitecapping
process, which is still widely considered to be the weak link in deep water wave modelling. Comparisons carried out against
measured data show that the wave prediction system generally provides reliable results, especially in terms of significant
wave heights and mean periods. By increasing the resolution in geographical space, the field distributions of wave energy
were analysed for both high and average wave conditions. The analysis and the wave prediction system developed are a prerequisite
for further investigations extended in time and with increased resolution in the near-shore direction. 相似文献
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文章介绍了危旧桥加固改造工程中结构分离、刚性连接及铰接连接等桥梁纵向加宽缝处理方法的优缺点及应用情况,提出了一种结构分离法处理桥梁纵向加宽缝的新措施。 相似文献
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Paulus Teguh Aditjandra Xinyu CaoCorinne Mulley 《Transportation Research Part A: Policy and Practice》2012,46(1):22-32
The objective of this study is to explore whether changes in neighbourhood characteristics bring about changes in travel choice. Residential self-selection is a concern in the connections between land-use and travel behaviour. The recent literature suggests that a longitudinal structural equations modelling (SEM) approach can be a powerful tool to assess the importance of neighbourhood characteristics on travel behaviour as opposed to the attitude-induced residential self-selection. However, the evidence to date is limited to particular geographical areas and evidence from one country might not be transferrable to another because of differences in land-use patterns and land-use policies. The paper is to address the gap by extending the evidence using British data. The case study is based on the metropolitan area of Tyne and Wear, North East of England, UK. A SEM is applied to 219 respondents who reported residential relocation. The results identify that neighbourhood characteristics do influence travel behaviour after controlling for self-selection. For instance, the more people are exposed to public transport access, the more likely they drive less. Neighbourhood characteristics also impact through their influence on car ownership. A social environment with vitality also reduces the amount of private car travel. These findings suggest that land-use policies at neighbourhood level can play an important role in reducing driving. 相似文献
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本文采用基于设计波法的直接计算法对270 000m3的浮式液化天然气船FLNG进行整船结构强度评估.根据FLNG具体的结构形式和数值分析的最终目的将该装置的实际结构简化,选用适当类型的单元对该装置的结构进行离散而得到FLNG的整船有限元模型.基于三维势流理论并利用中国南海波浪散布图对FLNG进行水动力分析,得到了FLNG在典型装载工况下的波浪压力分布及设计波参数.通过把FLNG承受的波浪压力、惯性力、静水压力与重力等载荷分布到有限元模型上,得到FLNG在典型装载工况下全船的应力水平、应力分布和变形情况.该数值分析结果可在FLNG的初级设计阶段为船体结构强度分析提供有效分析依据,并为FLNG上部模块的设计开发提供船体变形参考. 相似文献
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基于粘性计算流体力学的方法建立三维数值波浪水池,模拟有限振幅波的传播,并计算三维球体在规则波环境下所受的波浪力。采用两相不可压的RANS方程求解非定常不可压缩粘性流体,并采用流体体积函数(VOF)法对自由面进行动态模拟。通过编写用户自定义函数(UDF)设置边界入口速度和波高,实现在波浪水池尾部1~2倍波长区域消波,最终求出有限振幅波的模拟结果以及规则波中三维球体所受的波浪力,该结果与势流理论边界元法得到的结果在趋势上吻合良好。该研究方法为模拟分析其他海洋结构物在波浪中的水动力奠定基础,丰富与扩展了数值波浪水池的应用。 相似文献
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