【作者】 刘浩；

【导师】 冯仲仁； 陈波；

【作者基本信息】 武汉理工大学 ， 土木工程， 2017， 硕士

【摘要】 在科技和经济高速发展的现代社会,各类工程结构层出不穷,日新月异。它们的正常服役是人民幸福生活和社会平稳发展的根本保障。然而风雨灾害的出现给工程结构的安全带来了极大的威胁,甚至导致结构发生破坏,造成不可估量的损失。从提高结构抵抗自然灾害能力的角度出发,对工程结构抗风雨性能开展系统全面的研究,成为富有科学意义和工程实用价值的重要课题。基于此,本文以细长悬索结构作为主要研究对象,对其风雨荷载效应进行了详细探讨。首先对结构风雨荷载研究现状,索结构计算理论的发展历程进行了简要学习,总结了一些有用的结论。然后基于索结构有限元理论,推导了三节点等参索单元的刚度矩阵和质量矩阵,并对整体刚度和质量矩阵的集成以及边界条件的处理方法进行了讨论,最后结合MATLAB软件编写程序,对索结构动力性能进行了分析。接着研究了索结构的弹性模量、截面面积和密度三个参数对其动力性能的影响,得到了三种参数发生改变时,索结构频率的变化规律。然后推导了结构频率对其弹性模量、截面面积和密度的灵敏度系数计算公式,研究了索单元参数发生改变时,索结构频率的变化规律。然后介绍了降雨的基本理论,对降雨进行了分类,确定了雨滴谱分布函数,雨滴数密度及降雨空气占有率的求解方法。确定了雨滴运动过程中所需的截面面积和阻力系数的求解方法,在此基础上分别建立了雨滴在水平和竖向的运动方程,采用四阶龙格-库塔(Runge-Kutta)法,对雨滴在风作用下的移动末速度进行了求解。基于动量定理建立了雨荷载的力学模型,求解出不同风速作用下的雨荷载值,并对影响雨荷载的因素进行了研究。最后文章通过数值模拟方法生成了风速时程曲线,并结合上述章节的理论对雨滴末速度时程以及动力雨荷载时程进行了模拟。然后将前述求解得到的静动力风雨荷载施加于索结构上,结合三节点有限元理论及Newmark-β法,编程计算了索结构在风雨荷载时程下的静动力响应。研究结果表明,考虑雨荷载作用时索结构的位移、速度和加速度响应均有所增加,且增值幅度随着雨强的增大而变大,因此雨荷载对细长悬索结构的影响不可随意忽略。更多还原

【Abstract】 With the rapid development of science and economy,various kinds of civil engineering structures are being constructed in the modern society,one after another with each passing day.Their safety on the time of normally working service is the fundamental guarantee for the people’s happy life and social development.However,some natural hazards like storms have brought great threat to these engineering structures.And some great damages were even caused by those storms,resulting in immeasurable losses.Thus,it has become a scientific and practical topic to study the anti-wind-rain performance of the engineering structures in the perspective of improving the structural resistance to natural disasters.To solve this problem,a slender cable structure was selected and its wind-rain load effects are studied in detail.Firstly,the research progress of structural wind-rain load and the calculation theory of cable structure were briefly introduced,and some useful conclusions were summarized.Then,a three-node isoparametric cable element was presented based on the finite element theory of cable structure.The stiffness matrix and mass matrix of the cable element are deduced.Some methods are discussed to integrate those matrixes and dispose the boundary condition.Finally,the dynamic characteristics of the slender cable structure were analyzed,using MATLAB language.Afterwards,the influences of Young’s modulus,cross-sectional area and density on the structural dynamic characteristics were studied.The variations of the frequencies dude to the changes of parameters were obtained.The formulas of frequency sensitivity coefficient to Young’s modulus,cross-sectional area and density of the structure were deduced.Then the paper studied the tendencies of structure frequencies with the changes of those parameters.The basic theory and classification of rainfall were also introduced in this paper.By the rain spectrum,the density and air occupancy of raindrops are calculated.The cross-sectional area and the resistance coefficient were determined.The equations of motion in the horizontal and vertical directions were established respectively based on theories above.The fourth-order Runge-Kutta method was used to calculate the final velocity of raindrops.Based on the momentum theorem,the mechanical model of rain load is established to get the rain load under different wind speed.Then,the influences of some typical factors on the rain load are studied.Finally,the stochastic fluctuating winds were obtained based on the wind simulation theory.The rain velocity and load time marching were also simulated using numerical method.The three-node cable element theory and the Newmark-β method were combined to calculate the static and dynamic responses of the cable under the wind-rain load.The results show that the displacement,velocity and acceleration response of the cable structure will increase when the rain load are taken into account.At the same time,the effects of rain will grow with the increase of raininess.Thus,the effects of rain on the cable structure shouldn’t be neglected casually.更多还原