典型矩形高层建筑风荷载与风振响应分析

对典型矩形高层建筑进行风洞试验,根据试验结果计算了各风向角下的等效静风荷载和风振响应,同时采用《建筑结构荷载规范》(GB50009-2012)计算方法对该建筑正交角度下的风荷载进行计算,结合风洞试验风荷载与规范计算结果,研究典型矩形高层建筑等效静风荷载和加速度响应分布规律。结果表明:结构基底风致响应最不利角度并非完全出现在正交角度,风洞试验楼层风荷载整体趋势与规范计算结果相同,数值上存在差异,宜以风洞试验结果为准,该结构的顶层加速度响应小于高规限值,舒适度满足要求。     

大跨开合屋盖风荷载与风致响应试验与数值计算研究

为研究屋盖开孔对大跨结构风效应的影响,在边界层风洞中开展了大跨开合屋盖刚性模型风洞测压试验,分析了结构表面风荷载分布特征,基于时域分析法研究了屋盖开合对风致响应的影响。结果表明:大跨结构模态密集,第一阶模态能量最大,高阶成分的贡献不容忽视;屋盖开洞能有效的减小屋面风荷载,降低位移响应与加速度响应,减小风振系数。研究结果可为大跨开合屋盖风荷载设计提供参考。     

高层结构群风压力分布与干扰效应

为研究群风环境中高层结构的风压分布特性与群风干扰效应,采用1:300缩尺刚性模型风洞试验,在24种风向角下分析了高层结构风荷载特性的群风效应,研究了结构的压分布特性与群风干扰效应。结果表明,现有《建筑结构荷载规范》的结构风压设计值不宜用于群风环境中高层结构抗风设计,而模型风洞试验可有效地反映群风环境中的结构风压特性;迎风面与背风面脉动压力系数较侧风面低,最大脉动压力出现在涡旋运动最强烈处,也是最大负压产生处;结构极值风压可以通过脉动风压的概率特性识别,进而对结构采取相应的加强措施。试验研究技术可靠,结果可用于该工程及类似工程的抗风设计参考。     

高层建筑表面风压干扰效应研究

基于刚性模型测压实验,研究了不同干扰条件下高层建筑表面风压特性。结果表明:(1)单体建筑表面迎风面风压系数均为正值,其余各面均为负值,且迎风面位于中上部的测点平均风压系数较大;(2)受到来流方向周边建筑的遮挡效应,迎风面转为负压;(3)周边建筑的干扰,使得表面脉动风压系数大于单体工况;(4)上风向周边建筑的干扰效应比下风向更为明显。获得的结果可以为此结构设计提供风荷载,同时也为其他建筑的抗风设计和风洞实验提供技术参考。     

悬挂网壳结构风压分布的环境影响因素研究

为了研究环境因素对机场大跨度悬挂网壳结构风荷载分布特性的影响,通过在SST k-ω湍流模型的基础上结合CFD技术对悬挂网格结构进行风洞试验数值模拟,验证了数值模拟方法的准确性并对比研究了周边建筑、围护结构、地势高低与支撑结构等不同环境因素下悬挂网壳风荷载分布规律,发现：周边建筑可以对风荷载起到遮挡效果,降低网壳表面风压,遮挡效果随着夹角的增大逐渐衰弱;有围护结构的封闭式悬挂网壳较开放式悬挂网壳存在更大的风压梯度,在一定程度上可以提高结构承风能力,但对于非规则网壳结构无规律可循,故在实际工程中,需根据情况具体分析;随着悬挂网壳结构所处地势高度的增加,其受到风压的影响程度有一定的增幅,但当地势变化差异不大时,结构受风扰动不明显;拱梁对结构表面风压分布趋势影响较小,对风荷载起到了遮挡作用,可以降低悬挂网壳结构风压系数值。     

湍流对高层建筑风压幅值特性影响的研究

风荷载是高层建筑设计的控制荷载之一,来流湍流对结构风荷载分布和风致响应有很大的影响,研究来流湍流对高层建筑风荷载的影响有很重要的实际意义。本文主要研究来流湍流强度对高层建筑风压幅值特性的影响。为形成不同的湍流强度,本文采用风洞试验的方法,共模拟了五种风场,对2种不同断面相同高度共2个模型进行了研究。结果表明,当湍流强度比我国D类风场的湍流强度明显增大时,模型的四个侧面的平均风压系数在数值上是增大的,但是在背风面和侧面的平均风压系数绝对值是减小的;在D+风场中,背风面和侧风面出现了小正压。特别是背风面平均风压系数增加量比迎风面前后对应位置增加量更大,从而使整个结构所受的平均风阻力减小。高湍流强度对高层建筑表面风压有明显影响(如小正压),可为高层建筑抗风设计提供参考。     

矩形高层建筑扭转动力风荷载解析模型

本文通过研究不同长宽比、高宽比的矩形棱柱体在边界层风洞中典型攻角下的扭矩，提出了矩形高层建筑扭矩功率谱密度、均方根扭矩系数和Strouhal数的经验公式，并对相干函数作了一定的探讨，建立了完整的扭转动力风荷载解析模型。该模型和试验结果吻合较好，证明它是合理有效的，可在此基础上建立高层建筑扭转动力响应频域计算方法。     

组合网壳屋盖结构风振响应分析及等效静风荷载

结合惠州会议展览中心风洞试验结果,对波浪形组合网壳结构的风荷载和风振响应进行了分析,包括：24个风向角下屋盖荷载分布特性分析;结构整体和局部的自振特性分析;根据风洞试验结果对6个风向角（0°、30°、45°、90°、135°和180°）进行结构的风致动力响应分析。根据风振响应分析结果,基于响应的不同振动特点,提出将屋盖结构分为独立屋盖结构、屋盖结构两端挑棚结构和整体屋盖结构3个部分,指出对这3部分最不利的风向角分别为0°、30°、90°。最后综合考虑各个风向角下结构的响应及风振系数,给出了最终的风振系数建议值。     

建筑物表面风压以及风场的数值模拟与风洞实验研究

利用自主开发的模拟建筑物周围风环境数值模式“北京大学大气环境模式”(Peking University Model of Atmospheric Environment, PUMA), 通过求解非静力动力学方程, 模拟了一个特殊塔型结构建筑物周围的空间流场以及建筑物表面风压系数的分布特征, 同时与风洞实验的数据进行了对比, 对该拟建项目可能导致的风环境问题以及建筑表面风荷载进行了评估. 模拟结果与实验数据的比较显示, 两者在速度场与建筑表面风压系数具有较好的吻合度, 体现了该模式在风场以及压力场计算方面的良好性能. 但通过与实验结果的对比不难发现, 模式的结果在某些情况下与试验存在较大的误差. 造成这种偏差的原因, 一方面是模式现有的分辨率为水平方向2 m, 垂直方向3 m, 难以将塔型结构建筑物表面的气压变化完全精确的展现出来; 另一方面, 固壁面上格点的气压和周边空间气压分布之间关系的参数化方案, 仍需要进一步改进. 从整体来看, 该模式模拟结果与风洞实验基本吻合, 可以较好计算特殊形状钝体结构建筑物导致的风场以及风压分布情况. 研究表明该数值模式可用以评估建筑物的表面风压及周围的风环境, 在建筑物的风工程项目中具有良好的应用前景.     

超高层建筑风荷载计算中的振型函数

在我国高层建筑建筑规范中关于风荷载计算中有一振型函数表达式Φ_z=tan(π(Z/H)~(0.7)/4),这一公式在计算风荷载中被广泛采用。作者在对金茂大厦风振位移的观测和研究中,发现该公式与实际观测的结果不符。本研究给出金茂大厦这样的超高层建筑物的实测振型函数表达式:给出与建筑规范不同的风荷载振型函数,供建筑界参考;积累超高层建筑风振振型函数样本,以便在规范中给出符合实际振型函数的表达式,提高风荷载计算精度,设计出既经济又抗强风的超高层建筑。     

Evaluation of wind effects on a supertall building based on full‐scale measurements

This paper describes the results obtained from the full‐scale measurements of wind effects on a 70‐storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The field data such as wind speed, wind direction and wind‐induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the field data is conducted. The full‐scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude‐dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated. Copyright © 2000 John Wiley & Sons, Ltd.     

Wind flow and wind loads on the surface of a towershaped building: Numerical simulations and wind tunnel experiment

Flow structure and wind pressure distribution caused by obtuse obstacles are usually the focuses in Computational Wind Engineer researches (CWE). By solving the non-hydrostatical dynamic equations, PUMA model (Peking University Model of Atmospheric Environment) was developed and applied to simulating the flow structure and wind pressure distribution around a tower-shaped building. Evaluation about the wind environment and wind loads around the building was obtained through the analysis of the numerical simulation results and wind tunnel data. Comparisons between the simulation and wind tunnel study indicate that numerical simulation results agree well in the flow field and wind pressure distribution around the tower-shaped building. On the other hand, the horizontal grid interval of 2 m and the vertical grid of 3 m were still too crude to simulate the flow structure and wind pressure distribution on the building surface more exactly in detail; and the absence of suitable pressure perturbation parameterization scheme between the solid and the adjacent space also limits the accuracy of the numerical simulation. The numerical simulation model can be used to evaluate the wind environment and wind load around high buildings.     

Viscoelastic coupling dampers (VCDs) for enhanced wind and seismic performance of high‐rise buildings

As high‐rise buildings are built taller and more slender, their dynamic behavior becomes an increasingly critical design consideration. Wind‐induced vibrations cause an increase in the lateral wind design loads, but more importantly, they can be perceived by building occupants, creating levels of discomfort ranging from minor annoyance to severe motion sickness. The current techniques to address wind vibration perception include stiffening the lateral load‐resisting system, adding mass to the building, reducing the number of stories, or incorporating a vibration absorber at the top of the building; each solution has significant economic consequences for builders. Significant distributed damage is also expected in tall buildings under severe seismic loading, as a result of the ductile seismic design philosophy that is widely used for such structures. In this paper, the viscoelastic coupling damper (VCD) that was developed at the University of Toronto to increase the level of inherent damping of tall coupled shear wall buildings to control wind‐induced and earthquake‐induced dynamic vibrations is introduced. Damping is provided by incorporating VCDs in lieu of coupling beams in common structural configurations and therefore does not occupy any valuable architectural space, while mitigating building tenant vibration perception problems and reducing both the wind and earthquake responses of the structure. This paper provides an overview of this newly proposed system, its development, and its performance benefits as well as the overall seismic and wind design philosophy that it encompasses. Two tall building case studies incorporating VCDs are presented to demonstrate how the system results in more efficient designs. In the examples that are presented, the focus is on the wind and moderate earthquake responses that often govern the design of such tall slender structures while reference is made to other studies where the response of the system under severe seismic loading conditions is examined in more detail and where results from tests conducted on the viscoelastic material and the VCDs in full‐scale are presented. Copyright © 2013 John Wiley & Sons, Ltd.     

某海底沉管隧道风塔及下部结构抗震性能分析

为研究某海底隧道风塔及下部结构体系在塑性阶段的损伤破坏形态及特点,探讨在多重荷载作用下弹塑性静动力响应对结构的影响,建立了沉管隧道风塔及下部结构的大型三维有限元模型。采用基于能量原理的混凝土塑性及损伤本构模型,借助大型有限元软件ANSYS及ABAQUS分别对结构进行不同地震条件下的动力时程分析,对比分析振型、层间位移角及较为完整的塑性损伤破坏系数曲线。结果表明:不同设防地震下,结构整体性良好,振型及层间位移角满足规范要求;不同罕遇地震下,该结构的混凝土塑性拉压损伤最大时刻均发生在20 s,主要破坏区域在风塔与人防井及下部立柱的接触位置,且拉伸破坏系数明显高于压缩破坏。本文的研究成果可以为类似近海沉管隧道工程抗震设计提供一定的依据与指导。     

Effects of high modes on the wind-induced response of super high-rise buildings

For super high-rise buildings,the vibration period of the basic mode is several seconds,and it is very close to the period of the fluctuating wind.The damping of super high-rise buildings is low,so super high-rise buildings are very sensitive to fluctuating wind.The wind load is one of the key loads in the design of super high-rise buildings.It is known that only the basic mode is needed in the wind-response analysis of tall buildings.However,for super high-rise buildings,especially for the acceleration response,because of the frequency amplification of the high modes,the high modes and the mode coupling may need to be considered.Three typical super high-rise projects with the SMPSS in wind tunnel tests and the random vibration theory method were used to analyze the effect of high modes on the wind-induced response.The conclusions can be drawn as follows.First,for the displacement response,the basic mode is dominant,and the high modes can be neglected.Second,for the acceleration response,the high modes and the mode coupling should be considered.Lastly,the strain energy of modes can only give the vibration energy distribution of the high-rise building,and it cannot describe the local wind-induced vibration of high-rise buildings,especially for the top acceleration response.     

Research on wind-induced responses of a large-scale membrane structure

The wind-induced responses of a large-scale membrane structure, Expo Boulevard, are evaluated in this study. To obtain the wind pressure distribution on the roof surface, a wind tunnel test is performed. A brief analysis of wind pressure on the membrane roof is conducted first and then an analysis of the wind-induced responses of the structure is carried out using a numerical integral method in the time domain. In the process of calculation, the geometrical nonlinearity is taken into account. Results indicate that mean, RSM and peak values of the structure responses increase nonlinearly while the approaching flow velocity increases. Strong nonlinear characteristics are observed in the displacement responses, whereas the responses of nodal stress and cable axial force show minimal nonlinear properties when the membrane structure is subjected to wind loads. Different values of the damping ratio only have a minimal impact on the RSM response of the structure because the background component is a dominant part of the total dynamic response and the resonant component is too small. As the damping ratio increases from 0.02 to 0.05, the RMS responses of vertical displacement, nodal stress and cable axial force decrease by 8.1%, 6.7% and 17.9%, respectively. Since the mean component plays a significant role in the wind-induced response, the values of the gust response factor are not high for Expo Boulevard.     

高层建筑动态和静态风荷载的确定

简单介绍了利用高频天平测量高层建筑风荷载的原理和试验方法，讨论了高层建筑风响应的计算，提出了一种动态风荷载和静态风荷载沿高度分布的计算方法。结果分析指出：提出的求沿高层建筑高度分布的等效静态风荷载的方法适用于顺风向风力，应用于横风向风力有理论误差。