桅杆结构的动力稳定性分析

推导了弹性结构体系在任意动力荷载作用下的动力稳定性判别准则,用此准则对实际桅杆结构在随机风载下的动力稳定性进行分析,并在总结桅杆结构动力失稳的特性和规律的基础上,提出了简化的位移判别准则。     

Calculation of guyed masts in accordance with EN 1993-3-1 standard taking into account mast shaft geometrical imperfections

Selected problems concerning designing of guyed masts with lattice shaft in accordance with the “EN 1993-3-1: Design of steel structures. Part 3-1: Towers, masts and chimneys-Towers and masts” European standard have been described in this paper. The method of application of the mast shaft geometrical imperfections in calculations has been discussed. Based on the performed comparative analysis of a certain mast, the influence of such imperfections on the ultimate values of internal forces in the mast shaft has been demonstrated.     

考虑脉动风影响的斜拉索在支点激励下的非线性振动

应用柔性拉索的非线性振动响应计算理论,提出考虑横向脉动风荷载作用及支点激励的拉索非线性振动计算方法。以力学特性不同的两种斜拉索为对象,通过数值方法分析横风作用和支点激励下的钢索、CFRP拉索非线性振动响应,比较支点激励频率、风速、阻尼器对参数振动响应的影响。结果表明,在拉索基频f1以及两倍基频2f1的支点位移激励下,脉动风虽然导致拉索出现不规则的竖向和横向水平振动轨迹,但不会改变拉索的参数振动特性;横向风荷载对参数振动具有空气阻尼力的效应;总体上CFRP拉索的参数振动振幅小于钢索,特别当拉索跨度比较大时,CFRP拉索的振幅将明显低于同跨度的钢索;黏性阻尼装置的减振效果与拉索的结构条件有关,当拉索的无量纲参数λ(Irvine参数)较大时,阻尼器的减振效果不明显,反之当λ较小时阻尼器有一定的减振效果。     

基于CQC方法的大跨屋盖结构随机风振响应计算

本从线性结构随机振动响应计算的CQC方法出发，推导出适合于大跨屋盖结构随机风振响应统计量精细计算的算式，式中考虑了不同振型响应之间互相关的影响；同时指出，如需按CQC方法进行精细计算，就必须首先获得结构各点风荷载之间互功率谱密度函数的实部和虚部。     

高层建筑顺风向风振系数研究分析

以具体工程为例,采用线性滤波法模拟了顺风向脉动风场,在时域内计算了高层建筑结构风振响应,并对位移阵风荷载因子法、惯性风荷载法和荷载规范法所计算的风振系数进行了对比分析,以供参考。     

高层建筑结构在风荷载作用下的振动分析

通过介绍我国高层建筑结构风荷载设计方法、风荷载作用形式及由风荷载引起的结构振动,结合工程实例,进行了较详细的结构振动反应计算,以供同类型风荷载作用下的振动分析参考借鉴.     

随机振动研究生课程建设的探索与实践

课程建设是提高高等教育和人才培养质量的重要举措。针对随机振动课程特点和教学现状,立足研究生创新意识和实践能力的培养,结合重庆市研究生教育优质课程建设的探索与实践,从整合教学资源、完善教学条件、创新教学方法和改革考核方式等方面,系统阐述和全面总结了随机振动研究生课程建设的具体思路和实际做法。     

A parametric study of the free vibration analysis of rotating laminated cylindrical shells using the method of discrete singular convolution

This paper deals with the free vibration analysis of rotating laminated cylindrical shells. The analysis uses discrete singular convolution (DSC) technique to determine frequencies. Regularized Shannon's delta (RSD) kernel is selected as singular convolution to illustrate the present algorithm. The formulations are based on the Love's first approximation shell theory, and include the effects of initial hoop tension and centrifugal and coriolis accelerations due to rotation. The spatial derivatives in both the governing equations and the boundary conditions are discretized by the DSC method. Frequency parameters are obtained for different types of boundary conditions, rotating velocity and geometric parameters. The effect of the circumferential node number on the vibrational behaviour of the shell is also analysed. The analysis has been verified by comparing results with those in the literature and sufficient agreement is obtained.     

Reliability analysis of wind turbines under non‐Gaussian wind load

Based on translation models, both Gaussian and non‐Gaussian wind fields are generated using the harmony superposition method for examining the reliability of a typical wind turbine at operational and parked conditions. Using the blade aerodynamic model and multibody dynamics, wind turbine responses are calculated and then probability characteristics are analyzed in details. The short‐term extreme response distribution is estimated by the average conditional exceedance rate method at each mean wind speed bin, and the long‐term extreme response distribution is then determined by further integrating the short‐term extreme response distribution conditional on wind speed with the distribution of mean wind speed. Additionally, crack initiation life and crack propagation life are evaluated using the linear cumulative damage theory and linear crack propagation theory, respectively. The results indicate that non‐Gaussian characteristics of wind inflows have a noticeably greater influence on both extreme response and fatigue damage, and the Gaussian assumption cannot suit wind turbine in complex terrain.     

水平受荷桩的非线性无网格法分析

首先利用移动最小二乘近似得到求解域内的全局近似函数,再采用迦辽金法对控制方程离散,以获得无网格迦辽金方法的基本计算方程,并考虑到基桩承受水平荷载过程中的挠曲变形,探讨了无网格法在大变形问题中的具体实现;最后以湖南益阳茅草街大桥的水平静载荷试验为工程背景,采用本文理论编制考虑非线性大变形的无网格法计算程序对其进行分析。计算结果与现场实测数据吻合良好,验证了该方法的合理性与有效性,并指出桩周土体的强度和软化对基桩水平承载力的影响很大,可供工程参考。     

可液化砂土地铁列车振动作用下沉降特性分析

地层的不均匀以及一些特殊地层的存在,对列车振动荷载作用下的长期差异沉降具有较为显著的影响,直接影响到地铁列车营运期的长期安全问题。以佛山地铁2号线为例,通过数值模拟的方法对加固前与加固后可液化砂土层中的结构受力与地层沉降进行了具体分析,研究结果表明列车振动荷载对结构和地层整体影响较小,产生的位移较小。在列车长期循环振动荷载作用下,隧道会产生长期的沉降,沉降量初期发展较快、后期发展缓慢。对可液化地层进行注浆加固可以显著减少隧道沉降量。     

Nonlinear analysis of masonry-infilled steel frames with openings using discrete element method

Nonlinear numerical modeling of masonry-infilled frames is one of the most complicated problems in structural engineering field. This complexity is attributed to the existence of joints as the major source of weakness and material nonlinearities as well as the infill-frame interaction which cannot be properly modeled using the traditional finite element methods. Although there are many numerical studies available on solid masonry-infilled steel frames’ behavior, however, few researches have been conducted on infilled frames with openings. In this paper a two-dimensional numerical model using the specialized discrete element method (DEM) software UDEC (2004) is developed for the nonlinear static analysis of masonry-infilled steel frames with openings subjected to in-plane monotonic loading. In this model, large displacements and rotations between masonry blocks are taken into account. It was found that the model can be used confidently to predict collapse load, joint cracking patterns and explore the possible failure modes of masonry-infilled steel frames with a given location for openings and relative area. Results from the numerical modeling and previous experimental studies found in the literature are compared which indicate a good correlation between them. Furthermore, a nonlinear analysis was performed to investigate the effect of door frame on lateral load capacity and stiffness of infilled frames with a central opening.     

水平受荷桩非线性m法研究

大量试验表明,水平荷载作用的单桩的m值随桩身泥面位移增大逐渐减小,然而现有相关规范没有给出大位移情况下m值的取值范围和选取方法,这对于实际工程设计的参数选择造成了一定困难。在大量的桩基水平静载荷试验实测资料的基础上,采用数理统计的方法建立了不同土质条件下土体的m值与桩身泥面位移的相互关系式,可用来计算水平推力桩在大位移情况下的m值,算例表明该方法具有较可靠的精度和较强的实用性。     

首都博物馆屋盖结构的自振特性和风振系数分析

对首都博物馆屋盖结构进行了自振特性分析,结果显示其结构的频率密集且振型复杂。另外,为了工程设计的需求,根据结构位移风振系数的定义,提出了供工程设计应用的风振系数。     

马鞍型体育馆的位移风振系数分析

在频域内,对马鞍型体育馆结构考虑了多阶振型的影响,由结构风振动力的振型分解法,进行了该体育馆前20阶振型和振型耦合后风振动位移响应的分析和研究,得到了结构的模态特性及风振动响应,并根据本文定义的位移风振系数,对此结构提出了工程设计需求的风振系数.     

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.     

隧道竖向列车随机振动响应分析

根据列车系统振动的简化模型,用结构动力学原理模拟和分析列车竖向荷载,并根据地下结构地震响应分析的脉冲函数法计算原理,推导了利用脉冲响应函数计算隧道随机列车振动响应分析的数字特征的数学表达式,为隧道随机列车振动响应分析提供了一种分析途径。     

高层建筑地震作用计算的时域显式随机模拟法

目前我国GB 50011—2010《建筑抗震设计规范》中所推荐的振型分解反应谱法和时程分析法尚无法完全反映地震动随机性对建筑结构的影响,采用真正意义的随机振动方法计算复杂高层建筑地震响应的需求越来越迫切。结合新修订的广东省标准DBJ 15-92—2013《高层建筑混凝土结构技术规程》,全面介绍了结构地震作用计算时域显式随机模拟法的计算原理和实现方法,内容包括:1)通过迭代计算直接获得与现行规范反应谱完全等效的地震动加速度功率谱;2)给出基于精细积分和Newmark-β积分格式的结构地震响应显式表达式的构建方法;3)结合地震动随机过程的数值模拟,统计分析得到结构平均峰值响应。以广州西塔等4栋超高层和高层建筑为工程应用实例,显示了时域显式随机模拟法在高层结构抗震分析中的高效性和实用性。计算结果表明,时域显式随机模拟法和传统振型分解反应谱法的计算结果存在一定差异,最大差异可超过25%,反应谱法的内力计算结果普遍偏小。     

塔式起重机结构体系激振载荷的确定

探讨塔式起重机结构体系动态分析时激振载荷的确定方法。改变传统的二维建模、单向加载方式，根据塔机实际结构建立三维空间桁架模型，同时考虑吊重离地起升、变幅启动和回转启动的影响，在三维方向施加载荷，比只考虑离地起升和下降制动而把塔机结构简化为平面系统的计算更加符合实际。     

鞍形索网非线性振动计算方法研究

研究了鞍形索网屋盖振动时的受力特点,在连续性薄膜理论的基础上建立了矩形鞍形索网非线性振动的平衡微分方程,采用能量法推导出了鞍形索网的非线性自振频率的解析表达式,讨论并分析了激励幅值和索网拱度对索网的自振频率的影响,并得到各参数与自振频率的关系曲线,结果表明：激励幅值与索网拱度都是自振频率的增函数。