钢格构式塔架结构风振疲劳寿命中几个关键问题研究

Steel lattice towers are widely used in industry and daily life, the structure is generally light, flexible and low damping. The stress intensity of structure often meets the demand of related code during the course of design, but long-time and large amplitude vibration of structure cause wind-induced fatigue failure under wind load, which brings negative impacts to industrial production and daily life. The program focuses on three key problems on wind-induced fatigue life taking the characters of wind load and lattice tower into account, the main contents of the program are as follows.⑴ The synchronous aerodynamics on two model of lattice structure will be measured in the wind tunnel by simultaneously using two high-frequency base balance, and the coherence function of aerodynamics will be fitted based on results from wind tunnel test.⑵ The analysis method ,which meets the requirements of saving time and accuracy, will be established and then wind-induced stress responses of structure will be calculated during the each stage of failure evolution process based on results from wind tunnel test. ⑶Wind-induced fatigue damage of element will be calculated and furtherly safety residual equations for ultimate limit state of the structures will be established with consideration of joint distribution of wind speed and direction. The achievements of the program are useful to the analysis of wind-induced response and the design on wind-induced fatigue for steel lattice tower.

钢格构式塔架结构广泛的用于生产和生活中，该类结构具有轻质、柔性的特点。结构在设计时的强度往往是满足要求，但长时间较大幅度的风致振动会引起结构的疲劳破坏，这些结构的破坏给生产和生活带来很大的影响。本研究课题结合风荷载和格构式塔架结构的特征，对该类结构风振疲劳寿命研究中还存在的问题进行完善，主要内容包括：⑴同时使用两个高频底座天平对格构式塔架结构片段模型进行风洞试验，同步测量两个片段模型上的气动力，分析试验数据并拟合适用于该类结构气动力的相干函数；⑵在风洞试验测得气动力的基础上，建立既计算省时又满足精度要求的风振应力响应分析方法，并计算失效演化历程任意阶段中各个构件的风振应力响应；⑶分析构件的疲劳累积损伤并识别失效构件以及生成主要失效模式的安全余量方程,在主要失效模式的安全余量方程中体现风向和平均风速联合随机变量的影响。本研究课题为钢格构式塔架结构的风振响应分析、疲劳寿命设计提供参考。

钢格构式塔架结构广泛的用于生产和生活中，该类结构具有轻质、柔性的特点。结构在设计时的强度往往是满足要求的，但长时间较大幅度的风致振动会引起结构的疲劳破坏，这些结构的破坏给生产和生活带来很大的影响。本研究课题结合风荷载风速风向联合分布等特征首先建立了钢格构式塔架结构风振疲劳寿命可靠性分析的研究框架，本研究框架包括：失效历程各阶段中风振应力响应的分析模型、失效模式的识别以及安全余量方程的建立，该框架对于计算复杂结构风振疲劳寿命可靠性分析具有较大的参考价值；其次，为了验证该分析框架在工程当中的应用，对一典型的钢格构式输电线塔工程实例进行风振疲劳寿命可靠性分析，在工程实例分析过程中为了获得作用在结构上的气动力，同时使用两个高频底座天平对一典型的钢格构式输电线塔结构片段模型进行风洞试验，同步测量两个片段模型上的气动力，根据试验结果并考虑气动力的相关性，建立即计算省时又满足精度要求的风振应力响应分析模型。由于制作上部天平结构支撑设备的精度原因导致了该试验数据无法应用，具体的失败原因会在正文里详细阐述。