大跨度桥梁结构风荷载模拟研究

基于数值模拟方法的风速时程曲线在桥梁结构风振分析中被广泛采用。本文基于自然风特性,通过考虑结构节点间的风速时程相关性,采用AR模型模拟节点随机脉动风速时程。利用AIC准则确定模型阶数。对模拟所得的大跨度桥梁节点风速时程统计分析表明：AR模型可有效地模拟具有空间相关性、时间相关性的节点脉动风速时程,模拟精度、速度和计算稳定性均满足实际工程应用要求。     

风速时程AR模型及其快速实现

随着工程结构日趋多样化、大型化、复杂化，结构风振响应研究受到学术界、工程界的关注和重视，基于数值模拟方法得到的风速时程曲线在结构风振分析中被采用，自回归(AR)模型具有一系列优异性能，在时间系列分析中被广泛应用，本文基于自然风特性，通过考虑结构节点间的风速时程相关性，采用AR模型模拟节点随机脉动风速时程，并提出VC与Matlab混合编程模拟的快速实现方法．对模拟所得的网壳节点风速时程统计分析表明，AR模型可有效地模拟具有时间相关性、空间相关性的节点脉动风速时程，采用VC与Matlab混合编程快速实现方法，可较好解决模拟精度、模拟速度和计算稳定性的问题。     

新广州火车站风环境数值模拟研究与评估

建筑风环境问题涉及行人的安全与舒适,绿色建筑与节能等,作为新广州火车站风工程研究的专题之一,本文对新广州火车站的室外风环境问题进行数值模拟计算和分析。根据数值模拟计算得到16个方位风向角下的速度场分布,并结合当地气象统计资料,基于大概率发生事件的风环境品质评估标准,按照行人的坐、站立、行走等活动类别舒适性评判标准,对新广州火车站的站台和主出入口区域行人风环境品质进行了细致的定量评估,研究结果具有参考意义。     

Modern developments in wind engineering: part 3

This is the third in a series of review papers devoted to the state-of-the-art in wind engineering. Previous papers were published in the October 1981 issue of Engineering Structures, pp 233–240 and 241–248     

风力发电结构动力反应的一体化有限元模型分析

本文通过对风力发电结构系统地震作用下的动力反应的大量研究,提出了一种可用于分析风力发电结构的"桨叶—塔体—基础"一体化有限元模型,并结合土-结构相互作用的分析形成了另一种对比模型。利用上述分析模型对风力发电结构分别进行动力荷载作用下的模态分析和动力时程分析。结果表明,地震作用下考虑土-结构相互作用对风力发电结构动力响应的影响不容忽视,并且可为工程设计提供参考。     

Modern developments in wind engineering: part 4

This is the fourth in a series of review papers devoted to the state-of-the-art in wind engineering. The first three parts of the series were published in the October 1981 (pp. 233–241 and 242–248) and March 1982 (pp. 66–74) issues of Engineering Structures.     

新广州火车站高速列车过站数值模拟研究

列车高速过站引发的气动效应问题,是新广州火车站风工程研究的专题之一。本文基于先进的CFD数值模拟仿真平台,采用"动网格"技术对列车高速过站进行数值模拟研究,一方面对压力波的传递对屋盖结构压力分布的影响进行定量评估,为结构设计提供参考和建议;另一方面,给出高速列车通过时站台区域风速的空间分布范围,结合风环境舒适性评估标准(其中包含危险性风速范围),从而给出站台区域人员活动的安全和舒适范围。     

小波在风工程中的应用

简要阐述了一维小波分析的基本原理和计算方法，并介绍了国内外专家学者利用小波分析在风工程中的研究成果，由此可知小波分析在人工风速时程模拟、风速时程信号扩展、风速能量诊断和风致动力反应计算分析方面具有独特的应用价值，这些都是值得探索的。     

State of Florida hurricane loss projection model: Atmospheric science component

The State of Florida has developed an open, public model for the purpose of probabilistic assessment of risk to insured residential property associated with wind damage from hurricanes. The model comprises atmospheric science, engineering, and financial/actuarial components and is planned for submission to the Florida Commission on Hurricane Loss Projection Methodology. The atmospheric component includes modeling the track and intensity life cycle of each simulated hurricane within the Florida threat area. When a model storm approaches within a damage threshold distance of a Florida zip code location, the wind field is computed by a slab model of the hurricane boundary layer coupled with a surface layer model based on the results of recent GPS sonde research. A time series of open terrain surface winds is then computed for each zip code in the threatened area. Depending on wind direction, an effective roughness length is assigned to each zip code based on the upstream fetch roughness as determined from remotely sensed land cover/land use products. Based on historical hurricane statistics, thousands of storms are simulated allowing determination of the wind risk for all residential zip code locations in Florida. The wind risk information is then provided to the engineering and loss models to assess damage and average annual loss, respectively.     

基于罚函数的平均风速统计时距划分方法

针对目前结构风工程中风速特性统计分析均采用固定时距且不考虑统计时距内平均风速变化的假定,以三峡库区青草背长江大桥及舟山西堠门大桥桥址处实测风速资料为对象,采用罚函数对比法探讨了以风速样本均值和方差作为风速序列突变判据的时距划分方法,对比分析了风速样本的稳定时距的峰度、偏度、概型分布等统计特性。通过研究发现：采用P-variance方法得到的风速序列稳定时距远大于P-mean方法,风速平均值的波动趋势明显快于表征风速脉动能量的风速根方差的变化;基于罚函数对比法计算得到的风速稳定时距呈现出明显的正偏态分布特征,且Weibull分布可以较好地拟合风速稳定时距;采用罚函数对比法P-mean算法得到西堠门大桥桥址风场的风速稳定时距为569s,与规范中600s的计算时距非常接近,在一定程度上为规范600s时距的取值提供了依据,也证明了罚函数对比法在计算平均风速统计时距上的合理性;相比于传统10min固定时距,基于罚函数对比法的可变时距下风速序列的顺风向紊流强度和阵风因子的标准差均有不同程度的下降。     

基于风洞试验的风沙两相流耦合流场特性

风沙两相流结构的理论与研究方法已趋于成熟,主要集中在风沙物理运动本身和防风固沙工程方面,然而,将风沙运动现象及其对建筑结构物的作用效应相结合的研究还比较鲜见,继续开展风沙地区工程结构的抗风沙研究具有重要的现实与工程意义。通过风沙风洞试验,模拟了实际沙漠地貌下的风场特征,重点通过风洞顶部落沙研究了类似沙尘暴环境下的沙浓度、风沙流速度廓线以及湍流强度随高度的变化情况。通过控制相同风速、变化不同输沙率进行落沙,以此形成多种不同类型的风沙两相流耦合流场,并与净风工况相比较。试验结果表明:沙浓度梯度分布与落沙孔数量、控制风速以及高度均相关;风沙流场中沙颗粒的运动对风速剖面有一定的削弱作用,对湍流强度却有增强作用;风场中沙质量浓度沿高度方向的分布特征直接影响了各高度处风速和湍流强度的大小,沙浓度越大的高度处对风速的削弱程度越显著,且对湍流强度的增强程度越大。     

Wind and Fire Coupled Modelling—Part II: Good Practice Guidelines

The requirement to model wind is inherently connected with the modelling of many fire-related phenomena. With its defining influence on fire behaviour, spread and smoke transport, the solution of a problem with and without wind exposure will lead to substantially different results. As wind and fire are phenomena that often require different scales of analysis and approaches to modelling, their coupling is not a trivial task. This paper is the second part of a two-paper review of the coupling between fire safety engineering and computational wind engineering (CWE). Part I contained a review of historical interactions between these disciplines, sorted into six distinct areas: flames, indoor flows, natural ventilators, tunnels, wildfires and urban smoke dispersion. This part of the review contains practical information related to wind modelling in fire analysis, based on various available CWE best practice guidelines. As the authors conclude, the most relevant of these are guidelines related to urban physics and natural ventilation; however, many more are discussed and presented, together with the results of other essential wind engineering experiments and computations. Introduction of wind as a boundary condition is explained in details, both based on wind statistics, or meso/micro scale coupled modelling. The guidelines for wind/fire coupled analyses are subdivided into recommendations for: building the digital domain, spatial and temporal discretisation, the consequences of the choice of a turbulent flow model, and the procedure for optimising CFD analysis of both wind and fire phenomena.     

The International Association for Wind Engineering (IAWE): Progress and prospects

The International Association for Wind Engineering (IAWE) was born in 1975, at the 4th International Conference on Wind Engineering (ICWE), London, UK, in a pioneering stage of wind engineering. It operated, mostly informally, until 1999, when the IAWE Steering Committee Meeting at the 10th ICWE, Copenhagen, Denmark, decided to open a wide debate and study new tools to make the IAWE coherent with the impressive development in wind engineering. Following this decision, new IAWE by-laws were compiled and a renewed organisation was proposed to and accepted by the Steering Committee Meeting at the 11th ICWE, Lubbock, TX, 2003. This decision promoted several actions aimed at offering the international wind engineering community a more operative and efficient service and support. In particular, an Executive Board was constituted to drive the Association and its activities between two subsequent ICWEs; a Secretariat was established to administer the IAWE and to represent a reference point for the wind engineering community; several associations and societies were accepted into IAWE membership, and a wide network of links and cooperations was created among member organisations, supporting members and other individual contacts spread to all parts of the world; the official IAWE web site—www.iawe.org—was created; renewed liaisons were made operative with international organisations working in wind engineering and similar fields; IAWE Awards were instituted in the broad field of wind engineering; a better sequence of dates and venues of the most important wind engineering conferences was planned. This paper provides a general framework and some critical remarks on the progress and the prospects of the IAWE.     

我国建筑风洞建设的现状与思考

风洞试验是结构风工程研究中最重要、最直接和最有效的研究手段,而大气边界层风洞的建设与发展无疑会对提升风洞试验的质量和效率起到至关重要的作用。在评述建筑风洞的发展与现状的基础上,对三个具有风浪联合模拟能力风洞的建设情况进行介绍,最后就如何推动我国建筑风洞的发展提出几点建议。     

Neural network modeling of salinity variation in Apalachicola River.

Salinity is an important indicator for water quality and aquatic ecosystem in tidal rivers. The increase of salinity intrusion in a river may have an adverse effect on the aquatic environment system. This study presents an application of the artificial neural network (ANN) to assess salinity variation responding to the multiple forcing functions of freshwater input, tide, and wind in Apalachicola River, Florida. Parameters in the neural network model were trained until the model predictions of salinity matched well with the observations. Then, the trained model was validated by applying the model to another independent data set. The results indicate that the ANN model is capable of correlating the non-linear time series of salinity to the multiple forcing signals of wind, tides. and freshwater input in the Apalachicola River. This study suggests that the ANN model is an easy-to-use modeling tool for engineers and water resource managers to obtain a quick preliminary assessment of salinity variation in response to the engineering modifications to the river system.     

考虑极值风速方向性的围护结构设计风荷载概率估计方法研究

对于围护结构的设计风荷载（一定重现期的极值风压）,目前工程上普遍采用最不利值方法进行估算,这类方法不符合概率统计意义。只有统筹考虑极值风速和极值风压系数的随机性、方向性及相关性才能给出较为准确的设计风荷载。为此,提出一种全面考虑极值风速和极值风压系数随机性和方向性的围护结构设计风荷载概率估计方法。首先,提出了极值风压计算所需的三个要素,即各风向的极值风速分布、Cook-Mayne极值风压系数和风向相关性;然后,通过极值风压的概率分布理论分析,给出一个以上述三要素为输入的计算过程简便实用的围护结构风荷载估算公式;最后,以上海地区一栋高层建筑为例,通过与工程上常用最不利值方法相比,验证了本文方法的精确性和实用性。     

新旧荷载规范中高耸结构风荷载的计算与对比

本文结合新旧荷载规范,对高耸结构的风荷载进行了计算、分析与对比。通过分别对风压高度系数、风振系数的分析,认为新的荷载规范相对于旧规范,对于高耸结构的风荷载有了比较明显的提高,必须在实际工程中加以重视。文中还结合典型算例进行了验证。本文的研究工作除了供实际工程设计借鉴外,也可为后续荷载规范与高耸规范的修正提供参考依据。     

体育场内风流场和直缘主看台挑篷风压力分布的三维数值模拟

利用世界先进的计算流体工程软件CFX5 3,对我国设计的约旦哈桑体育场[1] 及其西看台上的大悬臂挑篷零度风向风流场和压力系数分布进行数值模拟 ,并将结果与风洞试验比较 ,以说明计算风工程在实际应用中的可行性。     

建筑结构风荷载与风环境数值模拟仿真研究与工程应用

本文首先对建筑结构风工程数值模拟方法的特点做了简明介绍; 接着提炼了风工程数值模拟研究的几个基础问题包括湍流模型与数值参数影响、平衡边界层的数值模拟、复杂建筑结构的数值风洞建模等, 介绍了这方面的最新研究进展和成果; 然后, 结合建筑工程实践, 概述了风工程教值模拟方法在解决复杂建筑结构风荷栽与风环境等问题中研究和应用成果; 最后, 对风工程数值模拟研究做了展望。其中许多成果为作者在研究和实践中的提炼和总结。对从事建筑结构风工程数值模拟研究具有一定参考价值。     

Time series analysis of wind speed using VAR and the generalized impulse response technique

This research examines the interdependence in time series wind speed data measured in the same location at four different heights. A multiple-equation system known as a vector autoregression is proposed for characterizing the time series dynamics of wind. Additionally, the recently developed method of generalized impulse response analysis provides insight into the cross-effects of the wind series and their responses to shocks. Findings are based on analysis of contemporaneous wind speed time histories taken at 13, 33, 70 and 160 ft above ground level with a sampling rate of 10 Hz. The results indicate that wind speeds measured at 70 ft was the most variable. Further, the turbulence persisted longer at the 70-ft measurement than at the other heights. The greatest interdependence is observed at 13 ft. Gusts at 160 ft led to the greatest persistence to an “own” shock and led to greatest persistence in the responses of the other wind series.