高层建筑结构考虑扭转简化分析的超元法

提出高层建筑结构考虑扭转简化分析的超元法,将纵横向各片抗侧力结构均简化处理成一根等效柱。空间协同分析时,采用超元法(每个单元由多根杆组成)计算等效柱的侧移刚度矩阵,自由度成倍减少。不论是框架、框剪结构还是剪力墙结构,计算侧移刚度矩阵、内力和位移时,都具有统一算式,计算简便。     

框支剪力墙结构简化分析的超元法

提出高层建筑框支剪力墙结构简化分析的超元法 ,即在通常的假定下 ,对上部剪力墙部分经连续化处理以后 ,简化为等效柱 ,底层框架部分在柱顶转角、侧移相等的假定下 ,视为等代柱 ,整个结构视为一个悬臂柱 ,然后按楼层划分成超级单元 ,用矩阵位移法分析。该法结构自由度很少 ,计算十分方便     

考虑轴压比影响时框架侧移计算的试验及理论研究

为研究轴压比对框架柱侧移的影响,以轴压比为框架柱的主要变化参数,完成了10根钢筋混凝土柱与5根钢柱压弯试验。试验结果表明:随轴压比增加,框架柱抗侧刚度增加,侧移减小;对于混凝土柱,裂缝间距和宽度都增大,裂缝越集中于柱底,压区混凝土破坏越严重,延性越差;对于钢柱,则压区屈曲越严重。随着名义偏心距的增大,二阶效应加剧,轴力对框架柱抗侧刚度的提高有所减弱;轴力对钢柱抗侧刚度的有利影响不及混凝土柱明显。结合试验数据,拟合了考虑轴压比影响的柱抗侧刚度计算公式。根据此公式计算内力侧移的框架算例表明,考虑轴压比影响时,框架结构侧移明显减小;轴力从上至下逐渐增大,轴压比对框架结构的影响愈大,结构侧移减小愈明显。考虑轴压比对框架柱抗侧刚度的影响,符合工程实际,能为现行规范对高层框架侧移计算的完善提供参考。     

弹性地基上十字交叉梁考虑上部结构影响分析的超元法

本文提出弹性地基上十字交叉梁考虑上部结构影响分析的超元法 ,即将房屋上部每榀框架各层梁与基础梁在X方向和Y方向均简化处理成一根等效梁 ,整个结构视为弹性地基上十字交叉梁系 ,导出等效梁的超级单元刚度矩阵 ,然后用有限元法分析。本方法计算简便 ,适应性强 ,且具有较高的精度。     

多层砖房抗震验算的简化方法

本文从串联柱、并联柱的观点出发,根据侧移刚度相等的原则,提出了砖砌体抗侧移等效截面积的概念,给出了等效截面积的计算公式,将砖砌体侧移刚度的计算转换为等效截面积的计算。     

用水平加强层控制高层结构的侧移——水平加强层的作用及其最佳位置

控制高层建筑变形的常用方式是加强抗侧力结构的刚度。但近年来美国和欧洲也采用水平加强层使内简体与外柱共同工作,以控制框筒结构的侧向位移。本文提出了一种简化计算方法,推导了计算顶点侧移值的公式,从而可找到水平加强层的最佳位置,还可用于计算高层建筑的自振周期。与有限元电算结果作了对比,效果良好。本文的工程背景是联邦德国法兰克福博览会大厦。     

高层建筑结构考虑楼板变形计算的超元法

提出高层建筑结构考虑楼板变形计算的超级单元法,即将每片抗侧力结构视为一根等效柱,楼板视为深梁,整个结构可按固定在地面上的十字交叉梁系,用矩阵位移法进行空间整体分析,自由度很少,计算简便.     

筒中筒结构在扭矩作用下的超元法

提出筒中筒结构在扭矩作用下的超元法,即是对外框筒及楼板连续化处理以后,视整个结构为一个悬臂杆,然后按楼层划分成超级单元,导出超级单元的刚度矩阵,用矩阵位移法分析.用该法分析变刚度筒中筒结构的扭转问题,自由度很少,计算简便.     

弱支撑框架柱计算长度系数的实用算法

《钢结构设计标准》给出了强支撑无侧移框架柱和无支撑自由侧移框架柱计算长度系数的计算表格,而对于介于这两者之间的弱支撑弹性侧移的框架柱,目前规范尚缺少相应的计算公式和表格。对此,本文基于弹簧-摇摆柱模型建立了弱支撑弹性侧移框架柱的扩展结构,通过临界荷载因子实现了扩展结构的临界力与原结构的临界力之间的转换,将求解框架柱计算长度系数的复杂二阶问题转化为计算压杆抗侧刚度的简单一阶问题,获得了一种确定弱支撑受压柱计算长度系数的实用算法,并提供了相应的计算表格。本文还推导了可按照无侧移框架柱计算稳定性的侧移临界刚度,此刚度可作为计算框架柱二阶效应时选择按照P-Δ效应还是P-δ效应的判别标准。最后,选取了2个算例进行计算验证,计算结果表明:该方法具有很好的精度及准确性,可供工程设计使用。     

结构抗侧力构件对振型平动系数的影响分析

结构在地震作用下产生的与平动相耦联的扭转效应,使结构在地震中的破坏更加严重.在房屋建筑结构设计中,设计人员可以通过结构抗侧力构件的合理布置,来增强结构自身的抗扭能力,减轻其在地震中所受的扭转破坏;然而,结构的抗侧力构件包括竖向抗侧力构件和水平抗侧力构件,究竟二者在增强结构自身的扭转能力中各自发挥着什么样的作用,本文针对这样的情况,讨论了结构与平动相耦联的扭转效应产生的原因、控制办法,以及竖向抗侧力构件和水平抗侧力构件分别对第一、二振型的平动系数的影响.     

Torsional vibrations and buckling of thin-walled beams on elastic foundation

The problem of free torsional vibration and buckling of doubly symmetric thin-walled beams of open section, subjected to an axial compressive static load and resting on continuous elastic foundation, is discussed in this paper. An analytical method based on the dynamic stiffness matrix approach is developed, including the effects of warping. The resulting transcendental equation is solved for thin-walled beams clamped at one end and simply supported at the other. A computer program is developed, based on the dynamic stiffness matrix approach. The software consists of a master program to set up the dynamics stiffness matrix and to call specific subroutines to perform various system calculations. Numerical results for natural frequencies and buckling load for various values of warping and elastic foundation parameter are obtained and presented.     

Torsional vibrations of open and variable crosssection bars

This work gives exact solutions for the torsional vibration frequencies of symmetric variable and open cross-section bars. An analytical method is derived to form the dynamic stiffness matrix of the bar, including the effect of warping. An example is given and compared to approximate results. The effect of warping is demonstrated.     

非对称抗震结构的扭转效应

文章分析了非对称结构由于刚心偏在一边、质心与刚心不重合，激起扭转振动。使远离刚心的刚度较小的构件侧移量、水平地震剪力显著增大的情况，并提出了减小扭转效应的措施。     

平面L形高层建筑的扭转效应分析及对策

平面L形高层建筑结构的刚度中心与质量中心偏离较大，在水平地震作用下平移振动与扭转振动扭耦合。分析由于耦合导致扭转效应动力增大的主要因素，并结合工程实例提出减少扭转效应的对策。     

NHRI-4000型高性能大接触面直剪仪的研制

介绍了NHRI-4000型高性能大接触面直剪仪研制与运用情况。采用数字PID模糊控制方式,实现垂直荷载和水平荷载的控制精度;采用MCS51单片机控制单元和多机通信等方式,实现垂直荷载和水平荷载的控制;在硬件电路上采用低通滤波等办法,在软件方面采用定量预测方法平滑测试信号,实现了传感器测量稳定性要求;引入Spcomm控件和定时控件,运用Delphi语言进行编程,实现了自动控制、自动采集、实时绘图等功能。     

Untersuchungen zur Drehbettung von biegedrillknickgefährdeten Trägern durch Sandwichelemente

Investigation of the torsional restraint of sandwich panels against lateral torsional buckling of beams. Experimental investigations and parametric FE‐analyses show that the torsional restraint of sandwich panels against lateral torsional buckling of beams can be expressed by a tri‐linear moment‐rotation‐relationship. Formulae are given for different profile types combined with sandwich panels for roof and wall for calculation of the parameters of this relationship. From this moment‐rotation‐relationship, which depends on the lateral load of the beam, the rotational stiffness c_{ϑ A} of the connection is obtained as secant stiffness. The rotational stiffness c_ϑ required for the design against lateral torsional buckling according to DIN 18800 part 2 is governed by c_{ϑ A}. The rotational stiffness values c_{ϑ A} of the connection, which so far were only known for two types of elements, can be calculated with this method for all common types of sandwich panels and different types of constructions.     

Consideration of the problem of shearing and torsion of thin-walled beams with arbitrary cross-section

In structural analysis it is often necessary to determine the geometrical properties of cross-sectional areas. The location of the shear center is of greater importance for a thin-walled cross-section. The purpose of this paper is the computation of the shear center of arbitrary thin-walled cross-sections using the finite element method. The coupling problem of shearing and torsional deformation of thin-walled beams based on Saint Venant's theory is considered. This problem of coupled shearing and torsional deformation was analyzed using the finite element method in which the matrix of shear rigidity and torsional rigidity were determined. The shear center can be obtained by determining the coordinate axes so as to eliminate the nondiagonal terms. Then, applying the stiffness matrix of shear rigidity and torsional rigidity obtained in the above, the stiffness matrix of the space framework elements in which the shear deformation is taken into consideration is developed.     

边梁对板柱结构侧向刚度影响的研究

板柱结构的周边布置边梁可以提高结构的抗震性能。采用等代框架法分析带边梁的板柱结构发现,边梁的抗扭刚度对内框架的侧向刚度影响较小。在边框架中,等代梁的抗弯刚度比边梁的抗弯刚度大,影响因素有板与边梁的抗弯刚度比、受扭构件与板抗弯刚度的比等,给出了边梁抗弯刚度增大系数的计算方法。     

Practical calculation of the torsional stiffness radius of multistorey tall buildings

The present paper refers to the definition of the torsional stiffness radii of multistorey tall buildings using both the continuous and the discrete model of the structure. The magnitude of the torsional stiffness radius of a building is the most important structural characteristic in order to explain the torsional behaviour of a building during an earthquake as it directly affects the building's torsional flexibility. The importance of the torsional flexibility of buildings is recognized by contemporary Seismic Codes that propose a grid of torsional provisions in order to avoid soft‐storey operation due to floor torsional vibrations around a vertical axis. However, contrary to single‐storey buildings, the torsional stiffness radius of multistorey buildings is not defined directly because both the translational and torsional stiffness of these buildings are expressed in matrix form. In the present paper, this weakness has been overcome using the continuous model of the structure, from which the torsional stiffness radius of a general monosymmetric multistorey tall system arises via a closed mathematical equation. The discrete model of the structure has numerically verified this closed mathematical equation. Copyright © 2007 John Wiley & Sons, Ltd.     

大跨度非对称悬索桥振动基频的参数敏感性分析

为了研究大跨度非对称悬索桥的动力特性,基于ANSYS软件建立了某大跨度主缆不等高支承悬索桥的三维有限元模型。在计算自振频率时考虑了表征结构非对称的参数,进行了前20阶模态分析,并分析了矢跨比、结构非对称参数、加劲梁抗弯刚度及主塔抗弯刚度等关键结构参数对其振动频率的影响。研究结果表明：不同的参数对非对称悬索桥振动基频的敏感性不同,一阶竖弯和扭转频率随矢跨比的增大减小,相对于正对称的振动频率,反对称的频率对矢跨比参数更敏感;非对称悬索桥的一阶反对称竖弯和扭转基频不受非对称结构参数的影响,而正对称竖弯和扭转基频随非对称结构参数的增大而减小;一阶横弯的自振频率对加劲梁刚度的变化非常敏感,当加劲梁的抗弯刚度增加到原来的3倍时,结构原有的振型次序发生了改变,但主塔抗弯刚度参数的变化对结构各向频率的影响很小,研究结果可为非对称悬索桥的结构设计和动力分析提供参考。