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。     

正菱形双塔楼高层建筑风荷载分布特征

通过风洞试验来研究正菱形双塔楼建筑的风荷载。根据设计软件特点,为将实验结果直接被设计软件所使用,将风压沿截面进行积分求出沿轴线和沿顺风向、横风向的合力,获得轴线整体体型系数,顺风向整体体型系数。同时将整体体型系数与单幢塔楼体型系数进行比较。     

非对称连体双塔高层建筑的风荷载分布特征风洞试验研究

以某近距离非对称连体双塔高层建筑为研究对象,基于刚性模型表面测压风洞试验,得到两个单塔楼的平均风压系数分布,并计算得到双塔楼局部、整体体型系数和平均整体体型系数,以此为基础研究了双塔楼结构的风荷载分布及其相互之间的干扰效应。结果表明:由于相邻塔楼和连体结构的干扰,塔楼局部迎风面出现负压,背风面出现正压;干扰效应对X向风荷载影响更为明显,双塔楼平均整体体型系数未超出规范要求,按规范设计偏于安全;中间连体由于"狭缝效应"Y向体型系数比较大,应加强风荷载设计。     

复杂塔冠对双塔高层建筑风压特性影响的试验研究

利用同步测压风洞试验方法,研究了3种典型风向角下圆角三角形截面双塔高层建筑顶部的花瓣形塔冠对建筑表面风压分布特性和风致响应的影响。基于试验数据,对建筑平均风压和极值风压等值线、整体体型系数、风荷载功率谱密度曲线以及基底合力(矩)进行了分析和比较。结果显示,复杂塔冠在整体上抬高了建筑顶部的风致绕流,使得部分风向角下建筑顶部附近的风压出现增大趋势;塔冠的存在同时使各楼层阻力和升力系数增大,且越靠近顶部增幅越明显;当风向沿着双塔形心连线方向时,由上游塔楼漩涡脱落形成的尾流激振现象十分显著,从而使得该风向角下的峰值加速度和横风向等效静力风荷载均达到最大,而塔冠的存在可能改变横风向风荷载的频谱特性,对于文中研究的双塔高层建筑,塔冠使得涡漩脱落频率略向低频转移,故使相应的峰值加速度和等效静力风荷载有所降低。     

超高层双塔中部联通异型建筑结构风洞试验研究

介绍了某超高层双塔中部联通异型建筑风洞试验方法与数据分析,对该超高层复杂结构的风压分布、风压系数及体型系数进行了研究,得到了可供设计使用的等效静风荷载与楼顶峰值加速度。结果表明,风压在建筑物的中上部及立面拐角区域较大,风吸力（负压）要大于风压力（正压）,整体上南塔（高度较低）风压小于北塔（高度较高）风压,总的等效静力风荷载主要由平均风荷载控制。研究成果可为该类结构抗风设计及相关研究提供参考依据。     

大跨越输电铁塔位移风振系数时频域计算分析

大跨越输电塔是风敏感结构,位移风振系数对跨越塔选型优化具有重要意义。以典型500 kV大跨越输电塔为研究对象,分别在ANSYS中建立了单塔和塔线体系有限元模型,通过模态分析得到了跨越塔前3阶自振频率,按照随机振动理论计算了跨越塔整体位移风振系数,跨越塔位移风振系数与高度无关。通过非线性风振响应时程分析,得到了跨越塔典型风压分段代表节点的位移时程曲线,基于有限元计算结果计算了跨越塔各风压分段的位移风振系数及整塔加权值,位移风振系数时域计算值沿高度变化不大。跨越塔位移风振系数频域计算值为1.54,比按照塔线耦合模型在时域计算的位移风振系数整塔加权值低12.9%。     

无锡蠡湖科技大厦表面风荷载研究

无锡蠡湖科技大厦刚性模型的风洞试验测量了模型表面的平均和脉动风压,给出了不同风向角下各测点的平均风压系数和体型系数。讨论了风场和风向角对平均风压系数和体型系数的影响,以及两个正方形截面塔楼的相互气动干扰影响特点,得到双塔高层建筑中各单塔楼的总体体型系数大于单体建筑的结论。     

广州西塔幕墙风压试验研究

针对广州西塔项目进行了同步压力测试试验,研究和分析了广州西塔的平均风压和极值风压分布规律。利用气象资料对幕墙风压进行修正,明显降低了西塔结构中上部的风压值,提供了更为科学合理的结构风荷载数据,同时也保证结构设计的安全性和经济性。通过截面体型系数的比较,可以看到西塔截面的体型系数和圆截面的体型系数具有一定的相似性。相关的研究结果可供结构工程师参考。     

不对称双塔楼高位连体结构设计

成都河畔新世界酒店为不对称双塔楼高位连体结构,双塔体型相差大,其中塔一平面为狭长的L形,塔二平面为平行四边形。塔一、塔二分别采用框架-剪力墙结构和剪力墙结构,两座塔楼在高位由钢桁架强连接组成整体结构,通过比较各种强弱连接的方式,论证了强连接的合理性。在进行单塔结构分析时,一方面需保证了单塔结构能独立安全工作,另一方面也要尽量调整两座塔楼的动力特性接近,以减少通过连接的相互传力作用。对重要的钢桁架与塔楼的连接节点进行精细的有限元计算分析,保证了强节点弱构件;进行超长结构的温度应力分析,据此配置了相应的温度加强钢筋;对结构进行动力弹塑性分析,定性地找出了结构的薄弱部位,并提出相应的加强措施;最后进行了振动台试验,验证了结构的抗震性能,并根据试验结果给出了施工图设计指导建议。     

不同长宽比高层建筑沿高度分布的风荷载

针对7种长宽比高层建筑进行刚性模型测压风洞试验,研究层阻力系数和层体型系数沿高度的分布特征,拟合获得层阻力系数和角度风分配系数公式,给出高层建筑x和y方向风荷载的计算公式,最后与各国规范的风荷载进行对比。研究表明迎风面的层阻力系数沿高度呈7字形分布,最大值出现在0.81～0.93建筑物高度;建筑顶部的层阻力系数较小,主要是受三维流效应影响;提出不考虑风振的矩形截面高层建筑风荷载沿高度分布的计算公式,该公式考虑了风向角、长宽比和地貌的影响,通过2520组试验数据验证了公式的有效性;各国规范迎风面风荷载沿高度呈指数或者对数变化,风洞试验值在顶部风荷载较小;背风面风荷载除GB规范呈指数分布以外,其他各国规范均沿高度不变,试验值沿高度基本不变;GB、ASCE和AIJ规范的整体风荷载和试验值比较接近,NBCC规范数值略小,而EN规范数值较大。     

基于风洞试验的苏通大跨越输电塔风振系数研究

苏通大跨越输电塔的结构形式有别于普通的钢结构杆塔,其塔身下部结构采用钢管混凝土、上部结构采用钢管,质量突变大,主要受风荷载控制,并且塔高超出GB 50009—2012《建筑结构荷载规范》的梯度风高度限制。为此,采用气动弹性模型和刚性模型的边界层风洞试验确定苏通大跨越输电塔的风致响应和气动力,基于试验数据计算不同风向角下的惯性力风振系数、位移风振系数和有效荷载风振系数,并进行对比。并通过有限元分析梯度风高度对惯性力风振系数的影响,同时将有限元分析得到的风振系数分布和加权值与DL/T 5154的风振系数规定作比较。结果表明：上述3种风振系数分布规律并不相同,由其分别确定的等效位移接近于试验值;考虑梯度风高度后,风振系数变小,分布形状影响小;苏通大跨越输电塔的惯性力风振系数加权值小于1.6,且风振系数由下到上不是单调增大。     

椭圆形双塔高层建筑风效应试验研究

多塔建筑的风荷载效应不同于单塔建筑,相互间存在风力相互干扰的群体效应,上风向建筑风尾流对下风向建筑存在增大效应.本文通过风洞试验,得到椭圆形高层建筑的风荷载效应、风荷载体型系数、风荷载相互干扰的增大系数,以供工程借鉴.     

Field measurement and aeroelastic wind tunnel test of wind‐induced vibrations of lattice tower

Lattice towers are among the most vulnerable structures during typhoons. In this study, the wind engineering research field base near Shanghai Pudong International Airport was used to measure the mean wind speeds and directions at a height of 10 m, as well as the accelerations atop a 40‐m high lattice tower during Typhoons Neoguri and Nakri to investigate the characteristics of the near‐ground wind and the responses of the lattice tower. Moreover, an aeroelastic model of the lattice tower was generated by the discrete stiffness method. Using the wind tunnel test of the aeroelastic model, the root mean square accelerations of the tower were studied with different wind speeds and directions. The responses of the tower in the across‐wind direction were found always higher than those in the along‐wind direction, which meant the vortex shedding of each single cylinder had an impact on the responses of the tower in the across‐wind direction. The test results were compared with those of field measurements to evaluate the accuracy of the aeroelastic model, and the two were generally in a good agreement. Thus, the aeroelastic model could precisely simulate the dynamic characteristics of a prototypical lattice tower using the discrete stiffness method.     

大跨越输电塔结构风振系数研究

在输电塔结构设计中,风振系数的取值非常重要。本文结合500kV崖门大跨越输电塔工程实例,通过输电塔结构时程分析,得到结构在风荷载作用下风振响应,统计了输电塔结构的风振系数取值,与多种现行规范进行比较,对大跨越输电塔结构抗风设计给出了建议。     

Effects of grid curtains on the wind loads of a high‐rise building

The effects of grid curtains on the local and overall wind loads of a high‐rise building are investigated in detail according to a series of wind pressure and wind force tests on rigid model in a wind tunnel. The effects of grid curtains on the mean and fluctuating wind pressures on windward and sideward walls when the wind direction is parallel to the geometrical axes are investigated, along with the effects of the most unfavorable wind pressures for all wind directions. Furthermore, the effects of grid curtains on the mean and fluctuating aerodynamic forces on the entire building are also analyzed for various wind directions, along with the effects of grid curtains on the aerodynamic force spectra when the wind direction is parallel to the geometric axes. The test results indicate that grid curtains affect the mean and fluctuating windward pressure slightly but greatly influence the large sideward negative pressures. Grid curtains increase the mean and fluctuating windward aerodynamic forces and reduce the fluctuating aerodynamic torsions. According to the aerodynamic force spectra, grid curtains can mainly affect the wind forces in the low‐frequency range. Copyright © 2015 John Wiley & Sons, Ltd.     

Wind effect of a twin‐tower super high‐rise building with weak connection

An analysis and estimation method of multibalance synchronous test is established to study the wind effect of a complex super high‐rise building with weak connection. First, the frequency domain method is applied to deduce the calculation process of the wind effect of the multitower structure on the basis of the high frequency force balance (HFFB) technique. Then, the synchronous force test of HFFB is conducted on a twin‐tower super high‐rise building connected by a bridge. The wind‐induced response and loads and the interference effect between the two towers are analyzed based on the wind tunnel test data. The displacement correlation between the towers and the relative displacement of the multitower structure are investigated. Results show that the maximum and minimum relative displacements in the along‐bridge direction are 0.26 m in the along‐wind direction and ?0.26 m in the crosswind direction, respectively. The channeling effect formed by the surrounding buildings is the main cause of the maximum cross‐bridge displacement. The influence of the correlation between the two towers can be ignored for the along‐bridge relative displacement. The results of the HFFB and high‐frequency pressure integral test agree with each other, thereby indicating the reliability and effectiveness of the proposed method.     

多回路输电塔风振系数研究

多回路输电塔由于质量与面积沿杆塔高度存在突变,按照规范公式求解风振系数将偏于危险。基于杆塔的集中质量模型,对输电塔风振系数的频域分析方法进行了探讨,推导了考虑背景响应的等效静力风荷载计算公式。通过比较阐明了多回路输电塔风振系数沿塔高的变化特点,分析了背景响应分量对风振系数的影响,并建议在进行多回路输电塔的抗风设计时,采用杆塔多阶振型的CQC组合计算等效风荷载。     

风压沿建筑物横向变化对规则巨型框架结构变形的影响

大量风洞试验研究表明,风压沿建筑物横向的变化非常明显,呈抛物线形状分布,而现行的GB50009-2001<建筑结构荷载规范>对风荷载平均风压取值的简化计算标准,并未考虑这一影响.在风洞试验的基础上,通过对试验数据的数值分析和拟合,得出了风压系数沿建筑物横向变化的简化计算公式.算例研究表明,风压沿建筑物表面位置的横向变化对规则巨型框架结构变形的影响较大,在设计中应予以考虑.     

Comparison of wind‐induced dynamic property of super‐large cooling tower considering different four‐tower interferences

Dynamic amplification effects caused by tower‐group interference is the most critical causes of wind‐induced destructions of super‐large cooling tower (SLCT), and four‐tower combinations are the most common tower‐group combining form. However, the dynamic amplification effects of SLCT of different four‐tower arrangements have not been studied systematically so far. The highest (220 m) SLCT in the world was taken as the target to conduct SLCT wind pressure measurement under 320 wind tunnel test conditions. Firstly, the stability performance under the design wind loads was analyzed. Then, the dynamic time‐history analysis was carried out, and the distribution characteristics of peak factors and values of extreme response were discussed. Furthermore, with a new concept parameter “tower‐group wind vibration coefficient” for the wind‐resistance design of SLCT, the distribution laws of two‐dimensional (2D), one‐dimensional (1D), and global tower‐group wind vibration coefficient were revealed under different four‐tower interferences. On these bases, we recommend the design parameters for wind‐resistance study of SLCT and the priority of four‐tower combination forms. The study showed that the dynamic effects of SLCT under different four‐tower arrangements were significantly different from each other and the tower‐group wind vibration coefficients proposed in this paper can reflect the interference effects of tower‐group more efficient than traditional design method. The results may become a useful database for the wind‐resistance design of SLCT and provide clues for the optimization of four‐tower arrangements in power plants.