【作者】 孙毅；

【导师】 李正良； 陈朝晖；

【作者基本信息】 重庆大学 ， 结构工程， 2010， 博士

【摘要】 由于山体的干扰作用,山地风场具有与平地风场截然不同的特征,如果仍采用平地风场计算方法计算山地高层建筑风致响应,势必会造成较大误差。因此必须从山地风场的基本特性入手,结合高层建筑在复杂风场中的风荷载,才能得到其振动特性。本文通过风洞试验手段,分别系统的研究了各种典型山地风场特性和高层建筑风荷载特性,由此提出了山地风场中高层建筑风致振动和等效风荷载计算方法,主要开展了以下几个方面的工作:①通过刚性山体模型风洞试验,建立山地风场中平均和脉动风速加速比数学模型。研究单个山体时,各种山体坡度、高度、来流平均风速等参数影响下,山地各位置平均和脉动风速特性;讨论来流方向有多个山体时,受扰山体各位置平均和脉动风速特性随遮挡距离、遮挡山体坡度、遮挡山体高度、连续山体个数等因素变化。根据试验结果建立山地风场计算模型,可分别计算单个山体坡度、高度、遮挡山体距离、坡度、高度和数量等各种参数改变时,山体各位置、各高度的平均和脉动风速。通过算例说明,计算模型与试验数据吻合较好。②通过高层建筑刚性模型风洞试验,建立山地风场中高层建筑风荷载幅值特性和频域特性数学模型。在风洞中建立了不同湍流度水平的风场,用以模拟山地风场中复杂的湍流度变化。进行各种高宽比和宽厚比矩形和圆形截面高层建筑刚性模型测压试验,通过改变来流平均风速和湍流度,讨论不同高度顺风向、横风向和扭转方向风荷载平均值和均方根值、功率谱密度和横—扭相干函数等特性。根据试验结果建立矩形和圆形截面高层建筑顺风向、横风向和扭转方向风荷载系数平均值和均方根值计算模型、功率谱模型和横—扭相干函数模型,通过算例说明计算模型与试验结果基本保持一致,能较真实反应各种复杂山地条件下的高层建筑风荷载特性。③分析山体参数对高层建筑风致响应谱的影响。根据山地风场平均、脉动风速模型和高层建筑的幅值和频域风荷载模型,在频域上计算山地风场中高层建筑层风荷载功率谱;对于顺风向采用来流脉动风速相干函数,横风向采用涡旋脱落相干函数,得到广义风荷载谱;根据随机振动理论计算高层建筑风致响应谱。通过各种山体坡度、高度和遮挡山体距离的算例分析,讨论各参数对高层建筑风致响应的影响。④研究山地风场中高层建筑等效风荷载,分析山体参数对等效风荷载的影响。根据山地风场中特有的平均和脉动风速特性,研究高层建筑平均风荷载、背景和共振等效风荷载特性。通过实例,比较山体位置、山体坡度等因素对高层建筑等效风荷载的影响规律。更多还原

【Abstract】 Because of the interference of hills, characteristics of hilly terrain wind field are distinct from that of flat terrain wind field. It will cause severe errors to utilize algorithm in flat terrain wind field to calculate wind induced response of tall buildings in hilly terrain. In that condition, only combination of profile of hilly terrain wind field and wind load of tall buildings in complex wind field can get the characteristics of peak value of vibration. By means of wind tunnel tests, profiles of wind field in typical hilly terrain and wind load of tall buildings are systematically investigated. Solution of wind induced vibration and equivalent wind load is put forward. In this paper, some works are studied as follows:①By means of wind tunnel tests of rigid hill models, mathematical models of speed-up ratio of mean and fluctuating wind in hilly terrain wind field are established. When single hill exists,profiles of mean and fluctuating wind speed under different slope and height of hills, mean speed of wind are investigated. When it comes to the multiple hills, profiles of mean and fluctuating wind speed under different distance, slope, height and number of occluding hills are discussed. According to the results of tests, mathematicl models of hilly terrain wind field are established. Given slope and height of single hill, distance, slope, height and number of occluding hills, mean and fluctuating wind speed at every location and elevation can be acquired. Some examples are presented to demonstrate the model and tests are consistent.②Mathematical models of amplitude and frequency characteristics of wind load of tall buildings in hilly terrain wind field are established according to rigid model wind tunnel tests of tall buildings. Different levels of turbulence are produced to simulate the complex change of turbulence in hilly terrain wind field. Tests of rigid model of tall buildings, including rectangular and round section, several aspect ratio and width-thickness ratio, are achieved. Changing the mean speed of wind and turbulent intensity of inflow, characteristics of mean value, root-mean-square value and power spectrum density of wind load on along-wind, across-wind and torsion direction and coherence function between across-wind and torsion direction. Mathematical models of mean value, root-mean-square value and power spectrum density of wind load on along-wind, across-wind and torsion direction and coherence function between across-wind and torsion direction are established. Some examples are presented to demonstrate the model and tests are consistent. The models can be used to calculate wind loads of tall buildings on complex hilly terrain.③Effects of hill parameters on wind induced response are analyzed. According to mean and fluctuating wind speed models and amplitude and frequency models of tall buildings, wind load spectrum of tall buildings in hilly terrain wind field is calculated. Coherence function of fluctuating wind speed is adopted on along-wind direction while coherence function of vortex-shedding is adopted on across-wind direction to get generalized wind load spectrum. Spectrum of wind induced response of tall buildings is attained according to theory of random vibration. Examples of different slope and height of single hill, distance of occluding hills are analyzed, and the effects of parameters on wind induced response of tall buildings are discussed.④Equivalent wind loads of tall buildings in hilly terrain wind field are studied and effects of hill parameters on equivalent wind loads are analyzed. According to the particular profile of mean and fluctuating wind speed in hilly terrain wind field, mean, background and resonant wind loads of tall buildings are investigated. Some examples are calculated, and effects of location and slope of wind on equivalent wind load of tall buildings are compared.更多还原