群体高层建筑的峰值风压分布特征

基于同步测压技术,研究了不同宽度比和不同高度比（记为Br和Hr,分别表示施扰和受扰建筑的宽度与高度之比）的2个高层建筑在串列、斜列和并列布置时峰值风压干扰效应。结果表明：邻近施扰建筑的侧面峰值风压主要呈现放大效应,且宽度比越大（Br≤1时）,高度比越大,放大效应越明显,立面最高负风压系数绝对值可升高30%。迎风面放大效应区则主要集中在施扰建筑位于横风向间距为3b(b为受扰建筑的迎风宽度)的迎风区域内,立面最高正风压系数可升高40%。当串列间距较小且高度比小于1（Hr=0.8）时产生的三维绕流现象可使得受扰建筑侧面局部风压升高61%,迎风面边缘局部风压升高24%。并列布置时产生的峡谷效应引起足够的重视,试验测得最大干扰因子可达2.13且随并列间距的增大而减少,当并列间距超过9b时峡谷效应才渐趋消失。由试验结果回归得到的并列布置时的侧立面最大峰值风压干扰因子随并列间距变化的关系式具有较高可信度。     

并列布置超高层建筑间的风压干扰效应

在边界层风洞中使用同步测压技术详细研究了双并列和三并列超高层建筑在不同间距下建筑各个立面风压的分布特征并用干扰因子IF(定义为建筑受扰后的风压值和相应单体情况的风压值之比)来描述施扰建筑的干扰影响。结果显示:双并列建筑相临立面的平均风压和峰值风压最大干扰因子(IFmax)具有高度的线性相关性,且IFmax随建筑间距而单调衰减。总的说来,两个施扰建筑的干扰效应高于单个施扰建筑的干扰效应,由回归分析得到的反映双并列和三并列建筑侧立面IFmax随并列间距比变化的经验关系式具有较高可信度。对于背风面,两个施扰建筑的干扰产生的放大效应明显大于单个施扰建筑,单个和两个施扰建筑可使受扰建筑背风面平均风压系数分别升高16%和36%、并使迎风面和背风面的总压差系数分别增加5%和13%。     

两串列方形高层建筑局部风压干扰特性分析

对2个完全相同的串列方形高层建筑模型进行了受扰建筑风压测量的风洞试验.根据试验结果,分析了施扰模型相对位置和高度变化对受扰模型局部风压的影响.结果显示,高度比固定,迎风面平均风压在间距比小于3时为负压,大于3时为正压,侧风和背风面平均负风压及各个面脉动风压均在间距比等于3时取得最大值.高度比变化,间距比小于3时,迎风面...     

前方建筑对高层建筑风压分布的干扰效应研究

在大气边界层风洞中开展了某高层建筑群刚性模型测压试验,对比分析了不同前方干扰条件下受扰建筑物表面风压分布特性。结果表明:1)建筑前方无施扰建筑时,斜向布置的施扰建筑物以及并联布置的施扰建筑物对受扰建筑立面的正压影响较大;2)前方施扰建筑较低时,下部平均正压减小明显,最大高达70%,而高处则存在正压局部放大效应;3)前方施扰建筑较高时,迎风面的干扰因子在高度上分布是比较平均的,并且受到的遮挡效应十分明显。所得结果可为此类建筑进行结构风荷载设计提供参考。     

建筑(群)立面风驱雨压荷载的数值模拟研究

雨滴受风驱动斜向飘落形成风驱雨(WDR),雨滴撞击建筑墙面将产生雨压荷载。考虑极端气候降雨频繁出现及其对建筑影响的加剧,有必要开展WDR雨压荷载的研究。基于欧拉-欧拉多相流模型,以雨滴谱及雨滴降落末速度拟合的雨相体积分数,以及依据力平衡条件确定的雨滴速度作为雨相入口边界,采用Realizable k-ε湍流模型封闭求解N-S方程,利用此WDR模拟新方法对单体多、高层建筑及特定群体建筑WDR场进行模拟,分析掌握迎风面WDR雨压分布特性及其受风速、雨强影响的规律与特点,通过比较迎风面最大WDR雨压与相应纯风压的量值,揭示单体与群体建筑WDR雨压荷载的作用程度。结果表明,设计工程结构尤其是覆面结构时,应考虑极端气候下WDR雨压所引起的荷载作用。     

开洞超高层建筑的风致内压干扰效应

为研究超高层建筑风致内压的干扰效应,在不同干扰工况下对一典型开洞超高层建筑进行了内压风洞试验。分析了不同截面宽度、不同高度施扰建筑干扰下的平均与峰值内压干扰因子的分布规律,并通过功率谱分析,研究了有、无干扰建筑时脉动内压的能量分布。结果表明:有、无干扰下的超高层建筑风致内压近似服从高斯分布;串列布置时,随着施扰建筑与受扰建筑的截面宽度比的增大,内压干扰因子逐渐减小;在并列布置且侧面开洞时,平均与峰值内压均呈放大效应,且干扰因子随着宽度比的增大而随之增加,峰值内压干扰因子最大值为1.33,此时若并列间距较小时,旋涡脱落共振峰值消失,但Helmholtz共振峰值能量会被大幅提高;当串列布置且施扰建筑高度与开洞所在高度相近时,侧面开洞受扰建筑的峰值内压始终被放大,峰值内压干扰因子最大值为1.12。     

不同风向下某多层建筑表面风压数值模拟

针对单体多层无开洞建筑房屋开展了CFD数值模拟表面风压研究,采用ICEM软件建立风场数值计算模型,采用雷诺应力湍流模型、UDF自定义风速入口函数以及一阶迎风函数来定义离散控制方程的对流项,对建筑房屋模型在7个不同风向角的风速作用下的表面风压系数进行了分析。得出建筑房屋迎风面和背风面在不同风向角作用下风压系数分布规律的区别,同时验证了数值模拟结果与相关风洞试验结果趋势一致,数值基本接近。针对串列布置两栋房屋的表面风压相互干扰效应开展CFD数值模拟,定量与定性地分析不同风向下的风致干扰效应对目标房屋与施扰房屋不同位置表面风压的影响。其结果对建筑房屋表面风压的分布规律研究具有参考意义。     

阳台对低矮房屋表面风荷载影响的数值模拟研究

采用大涡模拟(LES)方法,以长宽高之比为1.0∶1.0∶0.5的平屋盖建筑为对象,在建筑立面上引入阳台后,对不同风向角下模型表面的风荷载进行了数值模拟计算。通过与风洞试验结果的对比发现,大涡模拟能较好地预测建筑物表面的风压分布。在此基础上,重点探讨了不同风向角下立面阳台对建筑物表面风压和绕流风场的影响,同时考虑了不同来流风场条件的变化对阳台作用效应的影响。研究结果表明,立面阳台的引入会明显改变气流在建筑表面的分离、再附着形式,使得表面风压沿高度方向上的分布发生变化;引起的变化主要集中在建筑物的迎风面,特别是在迎风面最上面一排阳台及其以上区域;随着来流风向角的增加,阳台对建筑迎风面上风压的影响逐渐加大。     

小截面建筑干扰下的高层建筑气动力及风致响应研究

上游来流经小截面施扰建筑可产生频率较高的漩涡,在较低的风速下会使受扰建筑发生涡激共振而受到较大的干扰作用。为此,通过同步测压风洞试验和风振响应计算,详细分析上游施扰建筑与下游受扰主建筑的截面宽度比为0.4时的受扰建筑基底气动弯矩、基底峰值弯矩响应以及结构顶部峰值加速度的干扰效应。结果表明：在B类和C类地貌风场下受扰建筑基底平均和脉动气动弯矩均表现为遮挡效应和弱放大效应,最大干扰系数仅为1.05;顺风向、横风向基底峰值弯矩响应和顶部峰值加速度的干扰效应都较基底平均和脉动气动弯矩的强;结构顶部峰值加速度的干扰效应明显强于基底峰值弯矩响应,其中在B类和C类地貌风场下的横风向峰值加速度均在串列位置(2b, 0)附近处呈现强放大效应,最大包络干扰系数分别为4.7和3.03。进一步对尾流涡激共振的干扰机理研究表明,基底峰值弯矩响应和结构顶部峰值加速度响应的放大效应干扰机理是一致的。对于受小截面施扰建筑影响的情况,仅分析气动力的干扰效应是不够的,必须考虑不同折算风速下的荷载响应包络干扰效应。     

Interference effects on aerodynamic and wind-induced responses for an upstream interfering building with small section size

上游来流经小截面施扰建筑可产生频率较高的漩涡，在较低的风速下会使受扰建筑发生涡激共振而受到较大的干扰作用。为此，通过同步测压风洞试验和风振响应计算，详细分析上游施扰建筑与下游受扰主建筑的截面宽度比为0.4时的受扰建筑基底气动弯矩、基底峰值弯矩响应以及结构顶部峰值加速度的干扰效应。结果表明：在B类和C类地貌风场下受扰建筑基底平均和脉动气动弯矩均表现为遮挡效应和弱放大效应，最大干扰系数仅为1.05；顺风向、横风向基底峰值弯矩响应和顶部峰值加速度的干扰效应都较基底平均和脉动气动弯矩的强；结构顶部峰值加速度的干扰效应明显强于基底峰值弯矩响应，其中在B类和C类地貌风场下的横风向峰值加速度均在串列位置(2b, 0)附近处呈现强放大效应，最大包络干扰系数分别为4.7和3.03。进一步对尾流涡激共振的干扰机理研究表明，基底峰值弯矩响应和结构顶部峰值加速度响应的放大效应干扰机理是一致的。对于受小截面施扰建筑影响的情况，仅分析气动力的干扰效应是不够的，必须考虑不同折算风速下的荷载响应包络干扰效应。     

The influence of the wind-blocking effect by a building on its wind-driven rain exposure

Wind-Driven Rain (WDR) is one of the most important moisture sources that affect the hygrothermal performance and the durability of building facades. The complexity of WDR has led to the use of Computational Fluid Dynamics (CFD) to predict the amount of WDR falling onto building facades. Recently, the CFD model for WDR simulation has been successfully validated for a low-rise building of complex geometry and for a range of rain events, providing confidence for further numerical studies. In this paper, the influence of the wind-blocking effect by a building on its WDR exposure is examined. Part of the latest WDR CFD validation study for the VLIET building and CFD simulations of the WDR distribution on four different single-building configurations are presented. It is shown that the wind-blocking effect is one of the main factors that govern the WDR distribution pattern. As a result, high-rise buildings do not necessarily catch more WDR than low-rise buildings.     

Wind-driven rain on the facade of a monumental tower: Numerical simulation,full-scale validation and sensitivity analysis

Wind-driven rain (WDR) is one of the most important moisture sources that affect the hygrothermal performance and the durability of building facades. The facades of the Dutch monumental building St. Hubertus show severe deterioration caused by WDR. Assessment of the amount and intensity of WDR falling onto the facades is necessary as input for numerical heat-air-moisture (HAM) transfer models to analyse the causes of the moisture problems and the impact of remedial measures. In this study, a numerical simulation method based on Computational Fluid Dynamics (CFD) is used to predict the amount of WDR impinging on the south-west facade of the tower of the building. The paper focuses on the numerical simulation results, the validation of these results and their sensitivity to two parameters: the level of geometrical detailing of the computational building model and the upstream terrain aerodynamic roughness length. Validation is performed by comparison of the numerical results with a dataset obtained from on-site WDR measurements. It is shown that the CFD simulations provide fairly good predictions of the amount of WDR impinging on the south-west facade of the tower, except for the lower part. It is also shown that the local effects of geometrical facade details are significant and can yield differences in WDR exposure up to 40%, while their effect at other positions is negligible. Finally, the sensitivity of WDR simulations to the upstream aerodynamic roughness length is discussed.     

Computational fluid dynamics simulations of wind-driven rain on a mid-rise residential building with various types of facade details

Numerical studies of wind-driven rain (WDR), reporting detailed analysis of rain exposure on building facades, focus mainly on simplified building facades. However, small-scale facade details have a large impact on the rain exposure of a building, redistributing WDR locally. The present study reports results of computational fluid dynamics simulations with Eulerian multiphase (EM) model for WDR on a stand-alone mid-rise residential building. The influence of facade details, namely roof overhangs, balconies and window sills, is analysed. It is shown that even a very small surface detail, such as a window sill with a size of 0.10?m, can decrease catch ratio by up to 37% and droplet impact speed by up to 40%. Numerical simulations also show the practicality of the EM model for detailed analysis of WDR intensity on a complex building and its ability to be used as a design tool.     

Intercomparison of wind-driven rain deposition models based on two case studies with full-scale measurements

Three different calculation models for wind-driven rain (WDR) on buildings are compared for two case studies for which full-scale measurements are available. The models are the semi-empirical model in the ISO standard for WDR (ISO), the semi-empirical model by Straube and Burnett (SB) and the CFD model by Choi, extended by Blocken and Carmeliet. This paper builds further on two generic studies in which these models were compared based on model theory and based on their application for idealized building configurations and for constant wind and rain conditions. In the present study, the models are applied to calculate WDR on the facades of a low-rise test building and a monumental tower building for actual transient rain events. The spatial and temporal distributions of WDR at the windward facade are determined and the model results are compared with each other and with the full-scale measurements. The agreement between the CFD results and the measurements is on average 20-25%, whereas the ISO and SB models show large discrepancies at many facade positions, up to a factor 2-5. The identification of the reasons for the discrepancies is based on the previous generic studies and on the detailed information provided by the validated CFD simulations. The reasons include: (1) the ISO and SB models do not take into account the wind-blocking effect; (2) they do not model the variation of shelter by roof overhang as a function of the wind speed and; (3) they only provide information for a limited number of building geometries. In spite of these deficiencies, these models provide a strong basis for further development. The deficiencies can be addressed with CFD, and it is suggested that future research should focus on improving the semi-empirical models based on the detailed results of validated CFD simulations.     

Guidelines for the required time resolution of meteorological input data for wind-driven rain calculations on buildings

An important question in wind-driven rain (WDR) calculations on buildings, either with semi-empirical formulae or with Computational Fluid Dynamics (CFD), concerns the required time resolution of the meteorological input data: wind speed, wind direction and horizontal rainfall intensity. Earlier work has indicated that the use of 10 min input data can provide accurate results, while the use of arithmetically averaged hourly data can yield significant underestimations in the calculated WDR amounts. This paper builds further on this earlier work by providing a detailed investigation of the parameters that determine the required time resolution for WDR calculations on building facades: (1) the averaging technique, (2) the building geometry and the position at the building facade and (3) the type of the rain event. It is shown that all three parameters can have a large influence on the required time resolution. Depending on these parameters, hourly or even daily wind and rain input data could provide accurate results, while in other situations they can lead to very large errors. Finally, guidelines for the required time resolution as a function of the influencing parameters are provided.     

Interference effects on local peak pressures between two buildings

Local peak pressure coefficients between two buildings were studied by using wind tunnel experiments for various locations, different height ratios of interfering building and wind directions. The measured local peak pressure coefficients were compared to those obtained previously from a study on an isolated building. This study also investigated interference effects for local peak pressures on a principal building with various configurations and different height ratios of an interfering building. The experimental results have been examined and presented from the viewpoint of cladding design. The results show that highest peak suctions on a principal building increased with increase in height ratios of the interfering building. The oblique configuration generated more severe peak suction than the tandem configuration. To examine the interference effects for local peak pressures in detail, interference factors for maximum positive and minimum negative peak pressures at each measurement point (i, j) of the principal building for all wind directions are presented and discussed.     

Aerodynamic interference effects of a proposed taller high‐rise building on wind pressures on existing tall buildings

When a large super high‐rise building taller than the surrounding tall buildings is built in a dense urban area, the aerodynamic interference effects of the surrounding buildings on the proposed building attract much attention, while the interference effects of the taller high‐rise building on the nearby existing buildings are often ignored. Based on a series of wind tunnel tests, the interference effects of a proposed taller high‐rise building, an adjacent equal‐height partner building, and relatively short background buildings on the target building's local wind pressures are analysed in this paper. Two‐dimensional numerical simulation are carried out to further understand the interference mechanism in some cases. The test results show that the influence of a nearby proposed taller high‐rise building may lead to wind‐induced damage on the interfered shorter buildings' envelopes. The envelope structures of other surrounding buildings facing the side of the proposed building need to be given more attention.     

单个周边建筑对工业厂房屋面平均风压的气动干扰效应

工业厂房通常处于工业厂区内,受周边建筑的干扰,其表面风压分布与单个独立厂房不同,相邻建筑会对风荷载产生影响。基于单个厂房与两个串列厂房刚性模型风洞试验,给出了不同工况下屋面的平均风压,分析了屋盖横向、纵向端部与中部测点的平均风压分布规律,对比了不同串列距离条件下受扰厂房与独立厂房屋盖表面平均风压分布,探讨了平均风压系数干扰因子随风向角及干扰距离的变化规律。试验结果表明：不同风向角时,干扰效应截然不同;干扰效应存在临界风向角。临界风向角一般保持在 30°~50°范围内,小于临界风向角时,干扰起放大效应;大于临界风向角时,干扰为遮挡效应。此外,运用最小二乘法拟合了干扰因子设计值实用计算式,为受扰厂房建筑屋盖表面风压的修正提供依据。