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591.
某城市90 m钢箱拱肋提篮系杆拱桥,主梁采用钢混叠合梁,拱肋截面高度和宽度在空间同时变化,并采用无柔性系杆体系和减隔震抗震体系.通过对该桥技术特点介绍和计算分析,可为同类型桥梁设计提供一定的参考. 相似文献
592.
本文利用快速多极子面元法的高效性与精确性,对近水面潜体在水平面曲线运动过程中的时域兴波势流问题展开研究。首先确定了自由面网格密度及时域更新方法以保证数值模拟的准确性,探索了椭球潜体在水下做直线运动与曲线运动时阻力系数与升力系数变化的区别,明确了曲线运动过程中各项系数的变化规律,并针对不同的偏航角度的兴波特性进行比较,研究偏航角度大小对于潜体兴波阻力、升力以及表面兴波波形的影响。研究结果表明,当偏航角较大时,表面兴波对曲线运动潜体所受阻力和升力影响均非常显著;随着偏航角度的变大,各波系间的相互作用更加明显,表面波形更为复杂,导致了兴波阻力激增,阻力及升力曲线均出现大幅波动且不对称性。 相似文献
593.
594.
吴俊涛 《船舶标准化工程师》2020,53(2):19-23,60
以某双体甲板运输船为例,使用DNV船级社的SESAM软件对其波浪载荷进行直接计算分析,并对比分析了采用“规范方法”与“直接计算方法”得到的波浪载荷值。结果表明,该双体甲板运输船属于低速排水型船,其波浪载荷的计算方法与高速双体船差别较大,“规范方法”主要适用于高速双体船及尺度较小的低速双体船。对于船长为60m及以上的低速双体船,采用“直接计算方法”更能准确地计算出其波浪载荷。 相似文献
595.
596.
串联浮筒锚泊系统的静力位形及内力分析 总被引:1,自引:1,他引:0
向量式有限元法作为一种结构行为分析的创新性方法,在处理复杂边界条件下的几何非线性问题方面具有极大优势。本文详细介绍了向量式有限元法的基本原理和建模求解过程,将锚线离散为一系列质点的集合,采用空间杆单元模拟质点间的相互作用。对比锚线在静水平衡状态下的特性响应,在此基础上对串联浮筒的不同方案锚泊系统形态、张力值以及回复力等特性进行深入分析。结果表明向量式有限元法与其他建模方法在位形确定和张力分析方面吻合度极高,而由于其在建模求解方面的简洁性,为各种锚泊系统的特性分析提供了一种新的数值模拟方案。 相似文献
597.
In an effort to uncover traffic conditions that trigger discharge rate reductions near active bottlenecks, this paper analyzed individual vehicle trajectories at a microscopic level and documented the findings. Based on an investigation of traffic flow involving diverse traffic situations, a driver’s tendency to take a significant headway after passing stop-and-go waves was identified as one of the influencing factors for discharge rate reduction. Conversely, the pattern of lane changers caused a transient increase in the discharge rate until the situation was relaxed after completing the lane-changing event. Although we observed a high flow from the incoming lane changers, the events ultimately caused adverse impacts on the traffic such that the disturbances generated stop-and-go waves. Based on this observation, we regard upstream lane changes and stop-and-go waves as the responsible factors for the decreased capacity at downstream of active bottlenecks. This empirical investigation also supports the resignation effect, the regressive effect, and the asymmetric behavioral models in differentiating acceleration and deceleration behaviors. 相似文献
598.
599.
Loads from storm waves can in some cases be dimensioning for offshore wind turbine substructures. Accurate determination of nonlinear wave loads is therefore important for a safe, yet economic design. In this paper, the fully nonlinear waves, realized by a fully nonlinear potential wave solver OceanWave3D, are incorporated into coupled aero-servo-hydro-elastic simulations for a reduced set of wave-sensitive design load cases, in comparison with the widely used linear and constrained waves. The coupled aero-elastic simulations are performed for the DTU 10 MW reference wind turbine on a large monopile at 33 m water depth using the aero-elastic code HAWC2. Effect of the wave nonlinearity is investigated in terms of the ultimate sectional moments at tower bottom and monopile mudline. Higher ultimate moments, 5% at tower bottom and 13% at monopile mudline as maximum, are predicated when the nonlinear waves are used. It could be explained by the fact that the extreme nonlinear waves, that are close to the breaking limit, can induce resonant ringing-type responses, and hereby dominate the ultimate load responses. However, the constrained wave approach shows marginal difference compared to the standard linear wave approach. It can be concluded at least for the present configuration that the industry standard approaches (linear and constrained wave approach) underestimate the ultimate load responses on offshore wind turbines in severe sea states. 相似文献
600.
An experiment of hull girder model subjected to near field underwater explosion at midship is implemented. High-speed photography is applied to achieve the time history of hog displacement of the hull girder model subjected to shock wave of undex. The determination method of hog distortion using these show-motion pictures is presented. The experiment also achieves the local plate distortion of the hull girder model. Based on these works, the damage mechanism and mode of hull girder subjected to near field undex at midship are discovered. Finally, the coupling effect between whole motion of hull girder and distortion of local structure is discussed. 相似文献