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991.
A mathematical model of a ribbon pontoon bridge subjected to moving loads was formulated using the theory of simply supported
beams. Two types of moving load models were used, the first a moving-constant-force model and the second a moving-mass model.
Using both types of loads, the dynamic behavior of a ribbon pontoon bridge was simulated while subjected to a single moving
load and then multiple moving loads. Modeling was done with the Simulink package in MATLAB software. Results indicated that
the model is correct. The two types of moving load models made little difference to the response ranges when loads moved on
the bridge, but made some difference to the response phases. When loads left, the amplitude of the dynamic responses induced
by the moving-constant-force model load were larger than those induced by the moving-mass model. There was a great deal more
difference when there were more loads. 相似文献
992.
In recent years, demands for car transportation by a ship have been increasing with favorable economic conditions in auto
sector, and the need of a pure car carrier (PCC) has grown quickly. A PCC needs huge parking space but smaller displacement
since a car is comparatively light for its volume. As a result, almost all PCCs have wide breadth, shallow draft and huge
structure above the water surface. These features cause some technical issues of a PCC, like lack of stability, effect of
strong winds on its resistance, difficulty of course keeping in rough seas, difficulty of berthing in strong winds, and so
on. To overcome these technical issues, one of the authors has proposed a new concept for a PCC. This is a trimaran PCC which
has very limited transverse bulkheads in the center hull by using two side hulls as fenders. In the present research, wind
forces acting on a scale model of the trimaran PCC were measured in the towing tank with a wind generator at Osaka Prefecture
University. Furthermore, in order to clarify the characteristics of wind pressure on the trimaran, height and width of tunnels
which are between a main hull and side hulls were changed. And then, in order to imitate a real ship, we used wind reduction
technology of corner-cut design for accommodation house of the ship. Moreover, the wind pressure acting on the trimaran was
compared with that on a mono-hull PCC. Using these experimental and theoretical results, an estimation method of wind pressure
acting on the trimaran PCC is deduced. 相似文献
993.
海上风力机安装技术研究(英文) 总被引:1,自引:0,他引:1
Wind power has made rapid progress and should gain significance as an energy resource, given growing interest in renewable
energy and clean energy. Offshore wind energy resources have attracted significant attention, as, compared with land-based
wind energy resources, offshore wind energy resources are more promising candidates for development. Sea winds are generally
stronger and more reliable and with improvements in technology, the sea has become a hot spot for new designs and installation
methods for wind turbines. In the present paper, based on experience building offshore wind farms, recommended foundation
styles have been examined. Furthermore, wave effects have been investigated. The split installation and overall installation
have been illustrated. Methods appropriate when installing a small number of turbines as well as those useful when installing
large numbers of turbines were analyzed. This investigation of installation methods for wind turbines should provide practical
technical guidance for their installation. 相似文献
994.
995.
新疆赛吾达格尔大桥采用45°斜拉式抗风缆,用简支弹性梁的Rayleigh近似法计算基频;在不同风速下用有限元计算抗风缆施加前后主梁跨中横、竖向位移以及扭转角度,考察抗风缆对大跨悬索桥静风稳定性控制的有效性。结果表明:抗风缆能显著提高桥梁结构的固有频率,产生十分有效的抗风效果。 相似文献
996.
深水网箱浮框系统的水动力研究 总被引:1,自引:0,他引:1
对深水网箱实际工况进行简化后,得到简化的浮框系统水动力模型。通过力学分析,推导出浮框模型的运动方程,以此编制数值模拟程序,可得到浮框模型在纵移、垂荡、纵摇的运动情况及迎流面、背流面系缆张力的大小,发现锚绳仰角偏大,对该现象提出解决方案。 相似文献
997.
998.
水轮机组结构—液体系统的动态特性分析 总被引:1,自引:1,他引:0
讨论了耦合系统自由振动的控制方程,着重对动水压力向量及附加质量阵的计算进行阐述,并对在水介质下的结构的动态特性计算的求解方法作简要说明,最后介绍一个实用例子得出了计算成果,该例表明考虑液体影响得出的机组自振频率比不考虑液体影响所得值明显下降,而各阶振型也有明显的不同。 相似文献
999.
1000.
沉管隧道工程管节浮运沉放对浮运水位和流速的要求高。南昌红谷隧道为国内首座内河中游沉管隧道,受季节降水影响,水位和流速变化幅度大,满足浮运条件的水文窗口较少。通过对管节受到的水流力和拖轮拖力计算,确定水文边界条件。采用声学多普勒流速剖面仪(ADCP)对浮运航道内关键点和控制断面流速、水位进行监测作为水文预报的基础。采用相应水位(流量)法和合成流量法相结合的方法预测隧址位置水位、流量,将预测的水位、流量结果导入数值计算模型计算浮运航道内的流场分布。现场实测表明,水位和流速预测误差为±30 cm、±0.15 m/s,满足管节浮运水文预报精度的要求,并有效指导浮运沉放水文窗口的选择,保障红谷隧道管节浮运沉放施工的安全。 相似文献