基于谱分解法的自锚式悬索桥桥梁风致抖振计算分析

自锚式悬索桥是一种大跨度柔性结构体系,该桥型经受脉动风作用时容易发生较大的抖振响应,对于该种桥型进行风致抖振的研究探讨具有较强的实际意义。以自锚式悬索桥武汉汉江六桥为工程实例,进行风致抖振分析。具体分析流程为:通过计算流体力学软件对桥梁进行气动分析,得到桥梁抗风分析方程中的重要参数静力三分力系数。通过对桥址处风场资料的分析,采用规范规定的风谱密度函数,利用谱分解法将脉动风谱转换成脉动风时程,同时结合准定常气动理论将风时程转换成风力时程实现气动力的时域化。利用有限元软件建立桥梁的空间模型并分析自锚式悬索桥动力特性。通过自编数值程序和有限软件的结合将风力时程加载在桥梁模型上,实现桥梁在时程风力作用下抖振响应的数值模拟。其计算结果表明:该桥在风致抖振作用下性能良好,结构具有良好的气动性。结合计算流体力学软件、数值分析软件、有限元软件的桥梁抗风计算方法和模式,可以在其他自锚式悬索桥风致抖振计算中参考使用。     

某新能源厢式货车导流罩外流场对比分析

为了获取某厢式货车加装导流罩前后的外流场特性,基于RNG k-ε模型并且对整车模型简化处理,获取了整车的速度矢量图、静压图和流线图,由分析结果可知,当未加装导流罩时,车厢的正面压力约为500Pa,其风阻系数为0.685。当加装导流罩时,导流罩的正面压力约为200Pa,其风阻系数为0.559,降低了22.4%,改善效果较明显。     

Wind Tunnel Test on the Wind-Resistant Behavior of a Long-Span Cable-Stayed Bridge during Erection

In order to investigate the aerodynamic behavior of the Sutong bridge over Yangtze River during erection, a 1∶50 sectional model of the bridge deck, a 1∶100 full aeroelastic model of the free standing pylon and a 1∶125 full aeroelastic model for the maxim cantilever configuration were built. The test results show that there was no serious vortex-induced vibration at the bridge deck, and that the free standing tower, the model scale and the turbulence intensity influenced static loading. The buffeting responses during the maximum cantilever configuration did not affect the safety of the bridge under construction.     

公路隧道纵向送排式通风竖井数量及其间距研究

近年来,随着纵向通风技术的成熟,越来越多的长大隧道采用竖井送排式纵向通风方式,这种通风方式首先要确定竖井的数量及其间距。文章根据隧道内通风时对于断面风速的限制要求,提出了相同坡度下长大隧道竖井数量的计算方法,分析了隧道路面坡度对于竖井间距的影响,得到了不同坡度下隧道长度的折算方法及竖井间距计算方法,并给出了实例分析,其研究结果可以应用在长大隧道的相关设计研究中。     

风电安装平台插桩过程的试验与理论研究

针对风电安装平台在多层土中的插桩过程,通过现场取样测试获取土壤的物理参数,并通过插桩试验得到其平均插桩深度,以此建立插桩过程的数值模型,对插桩阻力与深度的变化规律以及土壤的流动失效机制进行了研究。结果表明,经验法选取土壤弹性模量与实际相差较大,试验测出的平均插桩深度为7.3m;数值结果与试验结果吻合良好,证明了理论模型的正确性;土壤发生了表面隆起、空腔形成、壁面坍塌和土壤回流四种失效模式。     

风场作用下趸船区域溢油动态模拟研究

以舟山定海港区某油库码头为背景建立了风场作用下的趸船区域溢油动态模型。针对趸船区域可能产生油品溢漏的位置,对趸船区域的溢油运动情况进行了模拟分析。模拟结果显示,当泄漏油品为柴油(850kg/m3,0.003825Pa·s)、泄漏点宽度为0.5m、油品泄漏速度为1m/s时,受风场作用,发生在趸船附近的溢油事故,其溢漏油品不仅随潮水运动流动,还会大量的在码头与岸线之间的区域及码头两端部附近产生积聚。在进行溢油事故快速控制和污油回收时,需要重点针对该区域进行监控防治。     

800吨自升式风电安装平台的设计特点

800吨自升式风电安装平台是上海振华重工(集团)股份有限公司为江苏龙源振华海洋工程公司设计研发建造的一种新型风电安装平台。本文从总体布置、重量重心控制、锚泊系统、消防系统等方面介绍了该船的设计特点。     

Efficient optimization design method of jacket structures for offshore wind turbines

With the gradual implementation of offshore wind energy production, the future tendency is to expand into the deeper water. The jacket foundations will take the place of the present monopile foundations when the water depth increases. The foundations account for the majority of the construction cost for offshore wind farms, and the structural optimization of jackets will bring lucrative economic benefits. Structural optimization is a complex iterative process that requires huge computing costs. Therefore, this paper proposes a structural optimization method based on surrogate models to solve this problem effectively and swiftly obtain optimized design schemes of lightweight jackets for offshore wind turbines. The structural responses of jacket wind turbine systems under the equivalent static extreme loads with a recurrence period of 50 years are mainly considered in structural optimization design, and the key optimization variables of jackets are determined by parameter sensitivity analysis. The finite element models of jackets are transformed into surrogate models, and the genetic algorithm is employed to optimize the surrogate models directly. The optimized jackets are additionally verified through coupled dynamic analysis, besides, buckling strength and fatigue life are also checked. And local refined optimizations are carried out for the failure members. According to the optimized design schemes of lightweight jackets for 30 m, 50 m and 70 m water depths, it is demonstrated that the structural optimization design method is adequate and efficient for jackets of wind turbines. Parameter sensitivity analysis can cut the number of optimization variables in half to improve the optimization efficiency. Furthermore, the application of surrogate models can significantly speed up the optimization process by saving about 98.61% of the original time consumed. The optimization design method of the jackets for offshore wind turbines proposed in this paper is suitable for practical engineering, with high precision and efficiency.