Dynamic response and reliability analysis of tall buildings subject to wind loading

This paper explores the wind stochastic field from a new viewpoint of stochastic Fourier spectrum (SFS). The basic random parameters of the wind stochastic field, the roughness length z₀ and the mean wind velocity at 10 m height U₁₀, as well as their probability density functions (PDF), are obtained. It provides opportunities to use probability density evolution method (PDEM), which had been proved to be of high accuracy and efficiency, in computing the dynamic response and reliability of tall buildings subject to the wind loading. Principals and corresponding numerical solving algorithm of the PDEM are first presented. Then, the adopted model of the wind stochastic field is described briefly. The simulation method of the fluctuating wind velocity based on the SFS is introduced. Finally, as an example of the application of the PDEM, a 20-storey frame subject to wind loading is investigated in detail. The responses, including the mean value and the standard deviation, and the reliabilities of the frame are evaluated by the PDEM. The results demonstrate that the PDEM is applicable and efficient in the dynamic response and reliability analysis of wind-excited tall building.     

高层建筑结构的扭转反应控制

高层建筑结构扭转反应控制是设计中的关键问题,但在《高层建筑混凝土结构技术规程》(JGJ3-2002)中还没有这方面的具体规定。因此,有必要对《高层建筑混凝土结构技术规程》中控制结构地震扭转效应的主要方法进行解说和讨论:限制结构在考虑偶然偏心的水平地震作用下,每个楼层的最大位移和最大层间位移与该层平均位移和平均层间位移的比值(位移比)以及结构以扭转为主的第一振型周期Tt与以平动为主的第一振型周期Tl之比值(周期比);分析位移比、周期比和偏心率之间的关系,并说明计算偶然偏心影响和控制位移比、周期比的必要性和可行性,以及在单塔楼工程设计中的应用;对于多塔楼高层建筑结构,提出了控制扭转效应的设计建议:对上部无刚性连接的多塔楼结构,宜将各塔楼及裙房由裙房顶板处切开分别计算各自周期比;对上部有刚性连接的多塔楼结构,应采用整体结构模型计算并验算整体扭转和平动的周期比。     

Lateral load response of belted tall building structures

This paper presents the results of an investigation on drift reduction in uniform and non-uniform belted structures with rigid outriggers under several lateral load distributions which are likely to be encountered in practice. Design aids in the form of graphical presentations of the somewhat complex solutions are provided to assist the practicing engineer in the preliminary design stages.     

Elastic analysis of asymmetric tall building structures

A simplified elastic hand method for estimating forces in asymmetric multi‐bent structures subjected to horizontal loading is presented. The structures may consist of combinations of coupled walls, rigid frames, braced frames and wall‐frames with shear walls. Results for structures that are uniform in height compare closely with results from stiffness matrix analysis. The method is developed from coupled‐wall deflection theory, which is expressed in nondimensional structural parameters. It accounts for bending deformations in all individual members as well as for axial deformations in the vertical members and is, therefore, more accurate for very tall structures. A closed solution of coupled differential equations for deflection and rotation gives the deflected shape along the height of the building. The proposed method of analysis offers a relatively simple and rapid means of comparing the shear forces and bending moments of different stability systems for a proposed tall building. The derivation of equations for analysis shown in this paper are for unisymmetric stability systems only, but the method is also applicable to general asymmetric structures. Copyright © 2001 John Wiley & Sons, Ltd.     

高层建筑结构在风荷载作用响应问题研究

随着社会经济的高速发展,城市低层建筑已不能满足人类的居住需求,高层建筑的出现应用满足了此方面的困难,在结构设计中,高层建筑相比于低层建筑承受更大的风荷载作用,而风荷载的不确定性因素导致结构设计的繁琐,同时基于低层建筑的荷载分析难以应用于高层建筑,因此研究高层建筑结构在风荷载作用下的响应是十分必要的。基于当前结构风工程的理论,对高层建筑结构下风荷载的研究方法进行了进一步探讨。     

Dynamic wind response of tall buildings using artificial neural network

This paper presents an alternative approach for predicting the dynamic wind response of tall buildings using artificial neural network (ANN). The ANN model was developed, trained, and validated based on the data generated in the context of Indian Wind Code (IWC), IS 875 (Part 3):2015. According to the IWC, dynamic wind responses can be calculated for a specific configuration of buildings. The dynamic wind loads and their corresponding responses of structures other than the specified configurations in IWC have to be estimated by wind tunnel tests or computational techniques, which are expensive and time intensive. Alternatively, ANN is an efficient and economical computational analysis tool that can be implemented to estimate the dynamic wind response of a building. In this paper, ANN models were developed to predict base shear and base bending moment of a tall building in along‐ and across‐wind direction by giving the input as the configuration of the building, wind velocity, and terrain category. Multilayer perceptron ANN models with back‐propagation training algorithm was adopted. On comparison of results, it was found that the predicted values obtained from the ANN models and the calculated responses acquired using IWC standards are almost similar. Using the best fit model of ANN, an extensive parametric study was performed to predict the dynamic wind response of tall buildings for the configurations on which IWC is silent. Based on the results obtained from this study, design charts are developed for the prediction of dynamic wind response of tall buildings.     

弦支筒壳结构在多点输入下的地震响应分析

将拉索与柱面网壳相结合,就可以形成新的弦支结构——弦支筒壳结构.以一实际工程为例,本文将分别采用地震波一致输入和考虑行波效应的多点输入分析方法对弦支筒壳进行地震响应分析.结果表明,地震作用下单层筒壳杆件内力和撑杆内力随时间的变化都是在某一数值上下波动,而下弦索内力随时间的变化则是波动着上升.与一致输入相比,多点输入时,单层筒壳杆件内力有些发生了方向改变,有较少一部分内力减小,大部分杆件的内力增大,且随着行波速度的减小,内力增大的杆件增多,幅度加大;一部撑杆的内力增大,也有相当一部分撑杆的内力减小,且随着行波速度的增大,二者对撑杆内力的影响趋于相同;下弦索中拉力或者增大或者趋于与一致输入时相同,且随着行波速度的增大,二者对下弦索中拉力的影响趋于相同.     

新型索承网壳结构非线性风振反应特性及参数分析

根据随机过程理论,考虑风压脉动及风的空间相关性,给出了具有空间相关性风场的计算机模拟方法,建立了一种适合大跨空间结构非线性风振响应计算分析的时域方法,并编制了相应的抗风设计程序.对一K8型索承网壳结构进行了非线性风振反应分析,分析表明该结构具有良好的抗风性能.通过改变几何、结构、荷载等参数,研究诸多因素对素承网壳风振反应的影响,结果表明矢跨比和撑杆长度是索承网壳抗风设计的主要控制参数.     

某高层建筑结构风致响应干扰效应研究

结合某高层建筑风洞模型试验,详细分析了不同工况下结构的风致响应,对干扰效应进行了深入研究。结果表明:基底弯矩的干扰效应主要表现为遮挡效应,遮挡使峰值弯矩减小,但是干扰位于侧风向或者下风向时,有可能使结构的峰值弯矩增大。受扰后,基底弯矩背景分量的变化规律与平均分量较为类似,共振分量的变化规律不明显。峰值加速度受扰后的变化也没有规律性。     

土钉支护结构的可靠度分析

指出土钉支护工程中存在大量的不确定性,应进行可靠度分析,基于极限平衡理论,采用验算点法进行了土钉支护结构内部稳定的可靠度分析,并与定值法分析作了比较,探讨了条分数、土钉水平间距、坡率等因素对安全系数及可靠指标的影响。     

Geometric nonlinear analysis of tall building structures with outriggers

In this paper, the geometric nonlinear behavior of wall‐frame tall building structures is analyzed. The governing equations of the wall‐frame systems with outrigger trusses are formulated through the continuum approach, and the whole structure is idealized as a shear‐flexural cantilever with rotational spring. The effect of shear and flexural deformation of the wall frame and outrigger trusses are considered and incorporated in the formulation of the governing equations. Geometric nonlinearity in the sense of von Karman is included in the formulation, and Newton–Raphson iterative method is employed to solve the nonlinear equations. A displacement‐based one‐dimensional nonlinear finite element model is developed. Numerical results for wall frame and mega‐column structures with outriggers are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, providing reasonably accurate results in early design stages of tall building structures. Copyright © 2011 John Wiley & Sons, Ltd.     

Random response of shell structures due to wind

An approach is outlined for the fatigue analysis of cylindrical shell structures subjected to the natural wind assuming the process to be a stationary random process.Two cantilever thin walled shells typical of chimney construction have been tested in a wind tunnel and comparisons made between measured strain spectra and computed values. The agreement obtained gives encouragement to the further development of the ideas proposed.     

A beam model for large displacement analysis of flexibly connected thin-walled beam-type structures

This paper presents a beam formulation for large displacement analysis of beam-type structures with flexible connections. Within the framework of updated Lagrangian incremental formulation and the nonlinear displacement field of thin-walled cross-sections, which accounts for restrained warping and the second-order displacement terms due to large rotations, the equilibrium equations of a straight beam element are firstly developed. Due to the nonlinear displacement field, the geometric potential of semitangential moment is obtained for both the internal torsion and bending moments, respectively. Material nonlinearity is introduced for an elastic-perfectly plastic material through the plastic hinge formation at finite element ends. To account for the flexible connection behaviour, a special transformation procedure is developed. The numerical algorithm is implemented in a computer programme and its reliability is validated trough several test examples.     

高层建筑结构舒适度的模糊可靠性分析

基于我国《高层民用建筑钢结构技术规程》(JGJ99—89)中关于人体舒适度验算的规定限值，并参考有关人体舒适度限值的标准，对高层建筑结构的舒适度进行了模糊可靠性分析，可供设计和修正规范时参考。     

地貌对高层建筑(群)风效应影响数值分析

高层建筑(群)风效应与地貌条件相关,分析掌握其内在关系是建筑布局规划和抗风设计的重要前提。基于雷诺时均模拟方法(RANS),引入具有分离流预测优势的SST k-ω湍流模型,以某高层建筑单体及群体风场为对象,模拟4类地貌条件下的风效应场,侧重分析人行高度(2m)风速场以及建筑立面的风压分布特性。分析结果表明,地貌除对人行高度的风速场影响明显外,对高层建筑表面风压系数影响也较为可观,实际工程应适当考虑地貌效应。     

Multi-hazard loss analysis of tall buildings under wind and seismic loads

This paper presents a framework for life-cycle loss estimation for non-structural damage in tall buildings under wind and seismic loads. Life-cycle cost analysis is a useful design tool for decision- makers, aimed at predicting monetary losses over the lifetime of a structure, accounting for uncertainties involved in the problem definition. For tall buildings, sensitive to dynamic excitations like earthquake and wind, it can be particularly suitable to base design decisions not only on initial cost and performance but also on future repair expenses. The proposed approach harmonises the procedures for intervention costs evaluation of structures subjected to multiple-hazards, taking into account the peculiar differences of wind and earthquake, in terms of load characterisation, type and evolution of damage. Relative effect of the two hazards on damage to drift- and acceleration-sensitive non-structural elements are examined. The influence of uncertainty in structural damping is also taken into account. It is shown that, although it is commonly believed that the design of a given structure is usually dominated by either winds or earthquakes, when LCC-based design is performed, both winds and earthquakes may be important.     

高层混凝土结构重力二阶效应的影响分析

传统的高层混凝土结构重力二阶效应分析大多是近似方法,对于实际高层结构,这种近似分析方法会带来较大差错。本文通过在单元几何方程中引入二次项,较为精确地考虑了重力二阶效应对高层结构受力特性的影响。根据高层结构的特点,建立了梁柱单元、单片墙单元和筒体墙单元三种非线性宏观单元,并编制了三维推覆分析程序。单元截面分析采用高斯数值积分方法,可对任意不规则截面进行分析,在非线性方程组的求解算法中引入了弧长算法,能够搜索到结构反应的全过程。对两栋不同结构体系的高层混凝土建筑进行了推覆分析,详细讨论了二阶效应对结构顶点侧移和基底倾覆力矩的影响。研究结果表明:对高度100m左右的高层混凝土结构,多遇地震作用下的强度和变形验算可不考虑重力二阶效应的影响,罕遇地震作用下的弹塑性变形验算一般应考虑重力二阶效应的影响。     

Seismic progressive-failure analysis of tall steel structures under beam-removal scenarios

Investigating progressive collapse of tall structures under beam removal scenarios after earthquake is a complex subject because the earthquake damage acts as an initial condition for the subsequent scenario. An investigation is performed here on a 10 story steel moment resisting structure designed to meet the life safety level of performance when different beam removal scenarios after earthquake are considered. To this end, the structure is first subjected to the design earthquake simulated by Tabas earthquake acceleration. The beam removal scenarios are then considered at different locations assuming that both ends connections of the beam to columns are simultaneously detached from the columns; thus the removed beam falls on the underneath floor with an impact. This imposes considerable loads to the structure leading to a progressive collapse in all the scenarios considered. The results also show that the upper stories are much more vulnerable under such scenarios than the lower stories. Hence, more attention shall be paid to the beam-to-column connections of the upper stories during the process of design and construction.     

应用SMA拉索的高层建筑结构振动控制研究

介绍了形状记忆合金的本构模型,并通过在高层建筑结构中装设SMA拉索对结构振动控制进行了研究,建立了被动控制高层建筑结构地震响应的运动方程,探讨了其控制原理和方法,为高层建筑结构振动控制设计提供了一种新方法。