日立电梯试验塔结构抗风设计

通过对日立电梯试验塔风洞试验结果的分析,表明试验塔原设计方案容易引起结构横风向共振,结构横风向的最大基底剪力以及基底弯矩的响应值可以达到顺风向的3倍左右。在结构设计中通过对建筑外形以及结构动力特性等方面的调整,使结构横风向的最大基底剪力以及基底弯矩的响应值减小至与顺风向基本相当,并在实际工程设计中予以采用。表明横风向作用在该类结构抗风设计中的起着不可忽视的作用,并针对这一特点提出了在结构设计中可以应用的加强措施。     

上海宝钢大跨桁架横风向风振性能研究

针对上海宝钢集团第一钢铁公司投资建设的“不锈钢扩建工程”项目,上料皮带通廊中跨度最大的部分作为分析对象,对其大跨桁架横梁在横风向的风振性能进行分析和验算,为该工程设计提供了理论依据。     

抗灾基站单管塔的横风向风振分析

基于结构横风向共振相应理论,结合抗灾基站单管塔实例,说明了通信单管塔中高阶振型横风向共振的可能性与计算分析的必要性。     

不规则高层建筑抗风静动力荷载分析和舒适度验算的软件开发

介绍了软件开发的背景、内容和原理.其内容包括不规则高层建筑顺风向静动力水平风荷载的分析和顺风向、横风向、扭转风向最大加速度的计算及人体舒适度的验算,同时软件具有前后处理功能,用户使用方便.     

高层建筑的横风向激励特性和计算模型的研究

将高层建筑的横风向激励分解为横风向紊流和涡激力激励。根据10个典型高层建筑模型的风洞试验结果,分别研究了两种激励的特性和计算模型,给出典型建筑的横风向紊流激励力系数、涡激力系数和相应的形状系数。特别着重研究涡激力功率谱函数和相干函数,总结出的结果可加深对高层建筑横风向荷载特性的认识,所建立的典型高层建筑的横风向荷载计算模型可用于实际工程。     

支承塔型设备的框架顶横风向风荷载分析

推导了支承在框架上塔型设备出现横风共振的上、下限塔径计算公式和框架顶部的横风向风荷栽计算公式。通过迭代计算求出给定基本风压、地面粗糙度类别、塔顶高度、框架高度等条件下,当框架顶横风向风荷栽大于顺风向风荷栽对应的塔径范围,框架顶横风向风荷栽与顺风向风荷栽比值最大值及对应的塔径。     

210m高异形烟囱横风向动力响应研究

研究了横风向风荷载对高耸异形烟囱的作用模式,采用计算流体动力学(CFD)方法对烟囱进行了非定常风场数值模拟,获得了烟囱横风向气动参数。结合某电厂210m高异形烟囱初步设计方案进行了横风向风荷载作用下的动力响应分析。     

变截面顶盖结构的横风向共振分析与计算

结合典型实际工程算例 ,建立了具有大面积造型变截面顶盖的横风向共振空间模型的计算方法 ,对横风向共振区有关参数的取值进行了讨论。通过计算结果 ,分析了横风向共振响应作用机理和发生的可能性。计算结果表明 ,第 5个振型可能发生横风向共振     

索膜屋盖结构横风向共振响应的时程分析方法

索膜屋盖结构的横风向共振问题与以往研究的高层 /高耸结构的横风向共振问题有较大区别。本文根据索膜屋盖结构的受力特点 ,发展了一种适合大跨索膜结构非线性横风向风振响应计算分析的方法 ,利用Newmark法和Newton Raphson法的思想推导了索膜结构在横风向风荷载作用下 ,结构的非线性动力增量平衡方程 ,并提出如何判别结构发生横风向共振的方法。文中还对有关参数的取值进行了讨论。最后本文利用ANSYS程序对某算例进行分析 ,得到其发生横风向共振时的风速     

横风向旋涡脱落共振响应分极及在规范上的应用

结构在风作用下,不但顺风向产生风振响应,而且横风向必然产生旋涡脱落风振．当横风向旋涡脱落频率与结构某阶自振频率一致时,结构产生极大的横风向共振,如不注意,结构将产生损坏或破坏,国内外有很多这类指导。本文基于国内外研究和规范资料,对本规范横风向共振依据的原理予以介绍,并对有关条文加以说明。     

钢管火炬塔架设计中径厚比限值对用钢量的影响

火炬塔架抗震设计标准给出的钢管径厚比限值远小于非抗震要求的限值。然而,通常情况下火炬塔架设计的控制荷载是风荷载,是否仍然需要满足抗震规范径厚比限制要求缺乏足够的研究。本文以某150m高火炬塔实际工程为背景,考虑常用基本风压情况,分别按抗风和抗震要求的径厚比确定构件,比较满足抗风设计与抗震设计要求时用钢量的差别,并找出对应的大震作用下处于弹性状态的设防烈度。分析结果表明,在基本风压不大于0.55 MPa时,按抗风要求径厚比确定的构件比按抗震要求确定的构件可节省用钢量20%左右,且在7度设防烈度大震作用下,塔架可保持在弹性范围;基本风压超过0.55 MPa后,径厚比改变对用钢量的影响不明显。综合考虑,火炬塔架设计宜先以抗风要求为主进行优化设计,然后进行抗震验算。     

电梯井道对自立塔架的风振响应

多功能高耸电视塔的电梯井道 ,其质量、刚度以及与自立塔架的连接关系直接影响到整个结构的风振效应。本文采用风振时程分析程序对具体实例进行了计算分析 ,研究了井道对塔架的风振影响 ,得到了对工程设计有一定实际意义的结论。     

张拉整体塔的结构特性及风振研究

本文在已有研究的基础上,以一座实用型张拉整体电视塔为例,对张拉整体塔的某些结构特性、抗风性能及施工进行了探索和研究。首先介绍了张拉整体塔的结构特性,主要包括:张拉整体塔的迎风面积、不同预拉力下的刚度、不同方向上的刚度及其自振特性与预拉力的关系。基于随机振动理论,运用谐波叠加法模拟了作用在结构上的脉动风,进而计算得到了张拉整体塔的风振响应,并进行了深入的谱分析,按照规范进行了抗风验算。然后比较分析了静力计算和动力计算的结果。     

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.     

风力涡轮钢结构塔楼的优化设计

为了使用于安装风力涡轮机的钢结构塔楼设计成本最小化,该塔楼结构形式为一个微锥形的焊接环肋壳体钢结构。用3个柱形壳单元组件来模拟45m高的钢壳,每个单元都有15m高,并且都有恒定的平均直径和厚度。根据欧洲规范1第2～第4章(Eurocode1,Part2～4)计算风荷载。设计中考虑壳体屈曲和环肋的局部屈曲。环肋非常必要,它可以阻止塔楼变成椭圆形。为计算生产成本,要考虑将这些钢壳加工为接近圆柱形状的加工成本和组装焊接部件的成本。成本最小化包括材料和生产成本最小化。最适宜的壳厚度、环肋的个数和直径采用Rosenbrock法直接计算。结果表明,采用环肋的数量越少,成本就越低。这个方法可以被用来预测微锥形塔楼的最小设计成本,满足细长型结构的需要,这种结构以动力荷载导致的弯曲为结构的主要荷载。     

Estimation of damping ratio of TV towers based on ambient vibration monitoring

Damping ratio is an important component in the dynamic analysis and plays a key role in design of supertall buildings. It is necessary to have reliable field measurement records for estimation of structural dynamic characteristics. The main objective of this paper is to estimate eigen mode damping ratio of TV towers as a kind of supertall buildings with the height of more than 250 m. In this regard, field measurements were performed on Milad TV tower, located in Tehran, which has a height of 435 m by ambient vibration monitoring. Damping ratio of this tower is determined using random decrement technique and compared with available data of a few other TV towers. For proposing eigen mode damping ratio of TV towers, it is shown that Rayleigh damping coefficients could not be calibrated properly for tall slender TV towers. A damping estimation chart of TV tower that is a function of natural frequency and structural aspect ratio is proposed, and the chart validity has been checked with field measurement results of other TV towers. The chart shows that structural damping for wind analysis proposed in design codes and standards is overestimated for tall slender TV towers. Copyright © 2011 John Wiley & Sons, Ltd.     

风力发电机组塔架的结构形式及其风载、地震作用综述

风力发电机组的塔架属于高耸结构,承受风荷载和地震作用,可采用钢筒、钢格构、钢筋混凝土筒和钢一混凝土组合筒等多种结构形式。本文简要分析了各种结构形式的优缺点及研究现状,认为随着风力发电机组越来越大型化,钢塔筒面临运输和施工吊装困难。而其它形式的塔架,如钢格构、钢筋混凝土筒和钢一混凝土组合筒塔架,具有易运输、易施工的优点,已获得一定应用,并可能进一步推广。目前,对钢塔筒的研究较多,而对其它形式的塔架研究较少;并且由于叶片数据缺乏,风力发电机组承受的风、地震作用的计算不很准确;此外,研究者分析的风力发电机组数量有限,所得结论不一定具有普遍性。     

±800kV特高压T型长横担输电塔风振特性研究

±800kV特高压直流塔是T型长横担输电塔型,属于风敏感结构,风与结构的相互作用十分复杂,风荷载常常是设计的主要控制荷载。本文以某一±800kV直流塔为工程背景,建立了详细的有限元计算模型,获得了结构的自振动力特性。在考虑节点风荷载空间相关性的基础上,利用Kaimal谱对结构的风荷载进行了准确的数值模拟。结合动力时程积分法,计算得到了结构的风致振动响应时程。研究了结构位移平均值、位移均方根值和加速度均方根值的分布特点,同时分析了结构各层的风振系数分布特点,并与我国规范进行了对比。通过研究,揭示了直流塔的风致振动特性,结果可作为直流塔结构抗风设计的参考。     

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.     

某风力发电分离式预应力混凝土塔架的设计和分析

本文考虑动力荷载作用下混凝土材料强度的提高,对某2.5MW风力发电预应力混凝土塔架在静力和动力荷载作用下的受力性能进行了分析,计算了预应力混凝土塔架最危险截面的轴力、剪力和弯矩,并验算了截面承载力,为钢-预应力混凝土塔架的设计提供经验。