Cross-wind response of tall buildings

A design procedure was developed using random vibration theory and uses mode-generalized cross-wind force spectra and aerodynamic data to calculate the cross-wind displacement and acceleration responses of tall buildings. The force spectra of a number of building shapes and sizes in both suburban and city centre type wind flow are presented. The proposed design procedure gives reasonable estimates of the cross-wind response, compared with wind tunnel measurements, at reduced wind velocities and at structural damping values consistent with modern habitable tall building design. This allows assessment of the structural requirements of tall buildings to be made at an early design stage, and also allows the designers to assess the need for more detailed and expansive wind tunnel model tests.     

Simplified prediction of wind-induced response and stability limit of slender long-span suspension bridges, based on modified quasi-steady theory: A case study

The Hardanger Bridge is currently under construction in Norway. It will have a main span of 1310 m and a girder that is only 18.3 m wide, which implies that wind-induced vibration is a major concern in the design. Buffeting response and flutter analysis of the Hardanger Bridge are treated in this paper. The self-excited forces are modelled using aerodynamic derivatives obtained from free vibration tests, quasi-steady theory, and a suggested modified quasi-steady theory. The stability limit predicted using aerodynamic derivatives corresponded well with the wind tunnel results, while the quasi-steady theory severely underestimated the critical mean wind velocity for the section model used in the wind tunnel tests. A new set of modified quasi-steady coefficients are suggested, where the experimental results of the aerodynamic derivatives are used to obtain frequency-independent model coefficients. The critical velocities predicted by the modified quasi-steady coefficients differ only by 4-5% from estimates based on the aerodynamic derivatives. The response predicted by the suggested simplified aerodynamic model is also presented, and the results indicate that adequate estimates are achieved.     

台风 “鲇鱼”作用下厦门沿海某超高层建筑风压特性的风洞试验与现场实测对比研究

为研究超高层建筑表面的风压特性,基于对厦门沿海某超高层建筑表面风压开展的现场实测和风洞模型试验,探讨了台风“鲇鱼”作用下超高层建筑表面的风压特性及其分布规律。研究结果表明：通过风洞试验和现场实测所揭示出的超高层建筑表面风压特性（平均风压系数、峰值风压系数）及其随风向角的变化规律基本一致;平均风压系数的现场实测与风洞试验结果在迎风面吻合较好,而背风面现场实测值明显较风洞试验结果小;峰值风压系数的现场实测与风洞试验结果除个别测点外相差较大。     

数值模拟大气边界层风洞中湍流模型的比较

风洞模拟试验是风工程研究的一种重要手段,在对大气边界层风洞进行数值模拟的时候,湍流模型的选取是影响模拟计算结果的至关重要的因素之一,本文针对大气边界层的风洞模型为考察对象对湍流模型进行了考察,考虑了各种湍流模型对计算结果的影响,并与实验结果进行了对比,旨在得出大气边界层风洞模拟中比较适合的湍流模型。研究发现在模拟大气边界层的风洞时,一般宜采用RNG k-ε模型,在计算资源和时间允许的情况下,建议使用雷诺应力模型。     

Large-eddy simulation of wind effects on a super-tall building in urban environment conditions

A combined study of large-eddy simulation (LES), wind tunnel testing and full-scale measurement is conducted for the evaluation of wind effects on a super-tall building in a complex urban area. To validate the numerical simulations, the wind tunnel experiments including synchronous multi-pressure and high-frequency force balance model tests are conducted in a boundary layer wind tunnel laboratory. The numerical predictions are then compared with the experimental results, demonstrating that the LES can provide comparable predictions of the wind effects on the super-tall building. Furthermore, the cross-validation of the predicted displacement responses by the LES against the wind tunnel and full-scale measurements are presented and the agreement among them is reasonably good. The main objective of this study is to explore an effective numerical approach for the accurate estimation of wind effects on tall buildings in urban environment conditions and promote the practical use of the LES in the wind-resistant design of complex structures.     

平导压入通风对寒区隧道风温场的影响性研究

为探明平导压入通风方式对高海拔寒区特长公路隧道风向、风速、风压和洞内温度场的影响性,以川藏公路雀儿山隧道为工程依托,通过数值仿真和现场测试,分析了不同通风方式下隧道洞内风场和温度场的分布及变化规律.研究结果表明:气热耦合三维数值计算显示风在横通道与主洞和横通道毗邻区域形成了明显的涡流区,平导洞内风压、风速明显高于主洞;...     

Numerical modeling of the flow conditions in a closed-circuit low-speed wind tunnel

A methodology for numerically simulating the flow conditions in closed-circuit wind tunnels is developed as a contribution to the general philosophy of incorporating Computational Fluid Dynamics (CFD) in wind tunnel design and testing and to CFD validation studies. The methodology is applied to the full-scale Jules Verne climatic wind tunnel in which experimental data have been obtained. Due to the specific features of this closed-circuit wind tunnel, the conventional CFD modeling approach, in which only the flow in the wind tunnel test section is modeled, is inadequate. To obtain accurate results the entire wind tunnel has to be modeled. In the numerical closed-circuit wind tunnel, the conventional flow inlet and outlet are replaced by a single “fan boundary condition”. Special attention is given to the theoretical background and the practical implementation of this type of boundary condition in the CFD model. The numerical model is validated for the case of an empty wind tunnel and for the case in which a block-type building is placed in the test section. It will be shown that this methodology can generally reproduce the wind tunnel measurements of mean velocities with an error equal to or less than 10% despite the occurrence of multiple flow separations upstream of the test section. This provides perspectives for the future use of this methodology as a tool for wind tunnel design and testing and for CFD validation purposes.     

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。     

新型超高层结构体系的抗风设计研究

在大气边界层风洞进行了“珠江城”商务写字楼大比例尺（1：150）模型风洞实验,通过对风洞实验数据分析,获得了基础等效静风荷载及结构顶部风致加速度响应,并将其结果与其他较小比例尺的两个风洞实验结果相对比,分析了模型几何缩尺比、周边建筑及平均风剖面对实验结果的影响。     

考虑特征湍流影响的体育场悬挑屋盖脉动风压谱模型

基于风洞试验对体育场悬挑屋盖的脉动风压谱进行系统研究,旨在得到适用于此类结构的脉动风压谱模型,为风振响应分析提供必要的信息。通过对屋盖表面脉动风压进行谱分析,可知在屋盖前缘处的风压谱与来流风速谱较接近,但屋盖后缘处则差异很大,表现出明显的漩涡脱落特征。因此脉动风压自谱采用来流谱与漩涡脱落谱相结合的形式来描述,并通过权数因子体现屋盖表面不同位置处流场作用的特点。对于脉动风压互谱则用指数衰减函数来表示,并确定了适用于悬挑屋盖的衰减系数。为验证所提出风压谱模型的有效性及特征湍流对风致效应的影响,对系列悬挑屋盖结构进行风振响应分析,风荷载时程分别采用风洞试验测得的风压时程、基于建议风压谱模型模拟生成的风压时程、按拟定常假设生成的风压时程。基于建议模型得到的响应结果与试验结果基本一致,基于拟定常假设的风振响应极值偏小10%～15%,均方根值偏小30%～40%,脉动风压谱建模中不可忽略特征湍流的影响。     

上海铁路南站风荷载试验研究

介绍了上海铁路南站模型风洞试验概况和主要试验结果。对这一大跨度圆形屋盖，分别进行了在无周边建筑和有周边建筑情况下的风洞模型试验。试验结果表明周边建筑对所测建筑的风荷载有较大的气动干扰影响。最后分析了屋盖上的典型测点的平均风压系数随风向角变化的曲线。试验结果对类似的圆形屋盖结构的风压分布具有参考价值。     

断面宽度对纵向通风隧道火风压影响研究

针对不同断面宽度隧道中发生火灾时的火风压变化问题,利用Fluent软件模拟隧道内发生火灾的情况,分析隧道宽度对临界风速的影响以及隧道宽度、火源功率和通风速度对火风压的影响。研究表明,火源功率较小时,宽度越小的隧道,临界风速越大;随着火源功率的增大,临界风速之间的差距减小。火风压中火区绕流阻力和热烟摩阻增量会随着风速的增大而相互作用。导致火风压会先随风速的增大而增大,到达一个峰值后会随着风速增大而减小,最后当通风速度增大到临界风速后趋于稳定的数值。随着隧道宽度的增大,通风速率对火风压的影响逐渐减弱。建立不同宽度隧道在不同通风速率和火源功率下的隧道火风压计算公式,为隧道火灾通风设计提供参考。     

Wind effects on the world’s longest spatial lattice structure: Loading characteristics and numerical prediction

The 486-m long roof structure of Shenzhen Citizens’ Centre is the world’s longest spatial lattice structure. This paper presents some selected results from a combined wind tunnel and numerical simulation study of wind effects on the extra-long-span roof structure. In this study, simultaneous pressure measurements on its entire roof are made in a boundary layer wind tunnel, and the measured wind pressures, such as mean, root-mean-square (rms) and peak pressure coefficient distributions on the roof are presented and discussed. Based on the measured data from a number of pressure taps, a numerical simulation approach using backpropagation neural networks (BPNN) is developed for the predictions of wind-induced pressure time series at other roof locations which are not covered in the wind tunnel measurements. The BPNN is trained with the pressure data time series measured from adjacent pressure taps. The good performance of the developed neural network is demonstrated by comparing the predictions with the model test results, illustrating that the BPNN approach can serve as an effective tool for the design and analysis of wind effects on large roof structures in conjunction with wind tunnel tests.     

大跨度中承式拱桥节段模型风洞试验

风致振动是大跨度中承式拱桥设计的主要控制因素之一,本文介绍了重庆菜园坝长江大桥风洞主桥节段模型静力三分力试验以及节段模型动态试验的主要内容及相应的结果,介绍了由于双拱干扰下的主拱静力三分力试验和涡振试验及其结论．试验表明,桥梁主桥具有良好的气动稳定性,主拱在风载下受力极为复杂。由于前榀拱尾流的影响,后拱阻力系数起伏较大。当两榀拱相距较近时,后拱的阻力系数为负数,随着间距的增大逐渐增大。试验结果将为大桥的抖振、涡振以及颤振分析提供依据。     

对称双塔楼建筑的风荷载分布特征

本文针对双塔楼建筑风场的相互干扰作用,通过风洞试验研究塔楼的风压分布,将风压沿截面进行积分求出沿结构柱网方向的合力,然后反算出沿柱网方向的整体体型系数,实现了把风洞试验结果换算为工程设计软件直接可用的数据。本文还讨论了风对高层建筑的扭矩作用,采用扭矩放大系数来考虑风致扭矩。针对某对称双塔结构的风压分布特征获得用于指导一般性对称双塔结构设计的风压和体型系数分布规律。     

错列超高层建筑群风荷载静力干扰效应的试验与数值模拟研究

对实际超高层建筑群进行了群体和单体塔楼两次同步测压风洞试验,通过两次试验测量结果,考察风向及塔楼位置对顺、横风向和扭转方向的主体结构承受平均风荷载的影响。同时,进行了CFD数值模拟研究。通过试验结果与数值模拟结果的对比分析,验证了数值模拟的可靠性,结合风压试验结果及CFD计算结果对建筑群干扰效应进行了分析和干扰机理说明。研究结果表明,对于建筑基底力而言数值模拟计算结果偏小,但是无量纲静力干扰因子数值计算和试验结果符合得很好,数值模拟计算可以用于风荷载干扰效应的定性分析。处于中间位置的2号塔楼风荷载静力干扰效应明显,干扰放大作用显著。     

Study on full-scale measurements of wind effect on super high-rise buildings in Pearl River Delta region during super Typhoon Mangkhut

对超强台风“山竹”侵袭时珠三角地区数栋超高层建筑的风致响应实测结果进行分析和总结，开展内伶仃岛缩尺模型风洞试验，获取该岛对气象站点风速的影响系数，并依此对观测风速进行订正，结合实测和风洞试验分析和评价深圳湾壹号7号塔楼(T7)的抗风性能。结果表明：不同高度、平立面外形的超高层建筑实测风致最大峰值加速度均超过10 cm/s2，且超高层建筑风振响应和建筑高度不存在相关性；在所有被测的建筑中加速度响应最小的建筑为高度342 m的T7，其最大峰值加速度仅为13.2 cm/s2；参数识别得到T7的模态频率和阻尼比显示均具有明显的时变特征，最大风速时段识别的模态频率整体上较有限元数据模拟结果增大21%，前两阶模态阻尼比分别为2.1%和1.7%；优化的气动外形和合理的朝向是T7抗风性能优良的主要原因，对于一般矩形平面的超高层建筑应避免使其窄边面向所在地的强风主导风向；采用订正后的风速值和参数识别结果对风洞数据进行重分析，结果显示计算值和实测值吻合较好，验证了前期风洞试验的可靠性。     

The effects of wind on people; New criteria based on wind tunnel experiments

Experiments on the effects of wind on people are described. About 40 people were involved in tests in a wind tunnel at the National Physical Laboratory. The wind tunnel was specially-adapted to produce gusty winds. The volunteers performed a number of everyday tasks at wind speeds of 4 and 8·5 m/s with and without turbulence. The steadiness and direction of walking were measured when the volunteers entered the tunnel and walked up and down. Forces on the ground were also measured. Six groups of volunteers gave subjective verbal assessments of wind conditions ranging from 4 to 12·5 m/s.From the experiments we have drawn conclusions as to what kinds of wind speed, gustiness and variation of wind speed are found to be tolerable, are found to affect performance, and are found to affect the people's balance while walking. We find people to be sensitive to variation in the wind so that previous criteria for acceptable wind speeds need to be revised downwards. New criteria are proposed to enable architects and planners to use wind speed and gustines data to predict whether wind conditions are likely to be acceptable or not.     

超强台风“山竹”期间珠三角地区超高层建筑的风效应实测研究

对超强台风“山竹”侵袭时珠三角地区数栋超高层建筑的风致响应实测结果进行分析和总结,开展内伶仃岛缩尺模型风洞试验,获取该岛对气象站点风速的影响系数,并依此对观测风速进行订正,结合实测和风洞试验分析和评价深圳湾壹号7号塔楼(T7)的抗风性能。结果表明：不同高度、平立面外形的超高层建筑实测风致最大峰值加速度均超过10 cm/s2,且超高层建筑风振响应和建筑高度不存在相关性;在所有被测的建筑中加速度响应最小的建筑为高度342 m的T7,其最大峰值加速度仅为13.2 cm/s2;参数识别得到T7的模态频率和阻尼比显示均具有明显的时变特征,最大风速时段识别的模态频率整体上较有限元数据模拟结果增大21%,前两阶模态阻尼比分别为2.1%和1.7%;优化的气动外形和合理的朝向是T7抗风性能优良的主要原因,对于一般矩形平面的超高层建筑应避免使其窄边面向所在地的强风主导风向;采用订正后的风速值和参数识别结果对风洞数据进行重分析,结果显示计算值和实测值吻合较好,验证了前期风洞试验的可靠性。