中美欧建筑结构抗震设计对比

抗震设计规范的制定与各国的建筑抗震设防水准及结构设计可靠度水平有关,同时还与各国的技术发展水平、经济实力和行政决策紧密相关,因此,各规范之间存在着显著的差别。本文从抗震设防等级与设防目标、地震作用计算与反应谱曲线等方面对中美欧抗震设计规范的差异进行了分析,详细阐述了三本规范之间的差别。按照三本规范中的有关条文,通过变换基本参数确定同一地区、相同场地条件下的反应谱曲线,根据计算结果对比分析了中美欧抗震规范中设计地震作用的取值标准。针对同一建筑结构,根据三本规范分别计算了结构的底部总剪力以及各层的剪力分布。结果表明,中国规范较欧洲规范偏于保守,与美国规范的差别与结构体系有关。该研究为我国建筑抗震设计规范的修订人员及抗震设计研究人员了解熟悉国外的抗震规范提供了帮助,有助于今后我国抗震规范与国际接轨。     

计算力学课程体系建设与思考————- 基于调查问卷分析

 通过对部分力学专业本科生和研究生的问卷调查, 了解学生对计算力学相关 方法与知识的掌握与使用情况, 并结合对学生相关调查现状分析的基础上, 探讨了计算 力学课程的内容与模式. 结合计算力学系列课程的开设与实践, 阐述了计算力学课程体系建 设与改革的一些思想和做法.     

国内外大学工科专业力学课程设置情况对比

调查了国内外若干大学机械、土木与航空宇航专业力学基础课程的设置情况,通过对统计数据的对比、分析,揭示了力学作为基础和专业基础在航空、机械、土木等专业培养计划中的重要性,指出了国际工程教育中“大力学”的趋势以及相应的在教学内容上所出现的整合与优化. 同时,文中还对国内有关专业力学基础课程的设置与教学提出了建议.     

跨世纪的中国计算力学

简要介绍中国计算力学的形成和发展,回顾了３０多年来中国计算力学工作者在计算力学基本理论、方法和应用软件等各方面所取得的成就,展望２１世纪中国计算力学的发展和可能的重要研究方向。     

带弹簧支撑结构的计算方法

针对工程中一类带弹簧支撑结构的静力分析,运用结构分析中的虚功原理推导该类结构位移计算的一般公式,介绍了带弹簧支撑超静定结构的静力分析方法. 经验证,其计算结果与有限元分析结果一致,证明该公式的正确性.     

漫话音乐中的力学

叙述音乐中与振动有关的力学现象, 如乐器的发声和音色, 音律学中的力学原理等.     

用振动方法测量流体密度

介绍了用振动方法则量流体密度的实验原理、实验装置和实验方法, 这是振动力学的一个教学实验,具有实际应用价值。     

关于扁担挑运力学原理的注记

扁担是常见的运输工具. 人双脚交替向前, 肩部高低变化可以激励扁担作为悬臂梁牵引荷物上下振动; 而行走速度的脉动可以引起悬挂于扁担两端的荷物前后摆动, 绳索对扁担的水平作用力和竖直作用力均周期变化, 后者可引起扁担振动而得到放大. 合适的扁担可以使挑担者在肩部承载较小时迈步向前.     

中国古代计量弓力的方法及相关经验认识

通过对现存传统弓箭制作工艺的调查,在对弓匠认识和解决具体的实践力学知识方法的考察基础之上,从对物理知识历史认识论的视角,对中国传统弓箭制作及使用中的实践力学知识进行了系统研究. 总结了中国古代计量弓力的单位和测试弓力的方法,分析了中国古代对弓体力学性能的认识. 并对前人争论的``郑玄发现弹性定律'的观点,从解读郑玄注文的含义、测试和解析弓体的力学性能、调查弓匠们的经验认识等多方面进行讨论,指出以前的研究者对这个问题的认识是错误的.     

结点位移计算的一种简单方法

推导了一种结点位移计算的简单方法,在平面桁架结点位移的计算和静不定杆系结构的变形几何关系的确定中应用方便.     

Fuzzy reliability analysis of aseismic structures

The structural reliability analysis taking account of the fuzziness in both earthquake loads and structural resistances is put forward in this paper. For this purpose, the concepts such as fuzzy earthquake intensity, fuzzy response spectrum, fuzzy structural response and satisfaction degree to fuzzy-random constraint are defined. This procedure may be taken as a basis for establishing a more rational optimum design of structures.     

圆柱壳自由振动特性分析方法研究

对传统解析法进行了改进,直接将复特征根代入边界条件构造了特征方阵;并基于圆柱壳Flügge 模型推导了位移形式的传递函数矩阵.在此基础上对比了改进的解析法、传递函数法、有限元法和实验方法获得的两端自由边界条件下圆柱壳的固有频率和模态.研究结果表明:改进的解析方法其特征方阵表达式简单且易于实现;同时通过与有限元和实验方法的对比,验证了改进解析法和位移形式传递函数矩阵的正确性;传递函数法相对于传统解析法对舍入误差敏感,可以通过增加字长的方式进行改善.     

不同均衡补偿模式下海底地形反演方法比较分析

针对不同均衡补偿模式下导纳函数存在不同的函数表现形式以及涉及诸多地球物理参数的特点,依据最新的全球地壳模型CRUST1.0获得了研究海域海水密度、地壳密度、地幔密度等参数信息。根据谱分析技术,在挠曲导纳函数受有效弹性厚度影响显著波段,采用迭代方法解算了不同有效弹性厚度环境下观测导纳和理论导纳的差值均方差,获得了研究海域有效弹性厚度最佳估值为11 km。分别采用未补偿导纳函数、挠曲导纳函数和Airy导纳函数构建了研究海域海底地形模型1、模型2和模型3,并与ETOPO1模型和GEBCO模型比较发现:模型1和模型2检核精度优于ETOPO1模型和GEBCO模型;相比于ETOPO1模型,模型1和模型2精度提高了49.04%和39.44%。海深分层检核统计结果表明:应用导纳函数构建的海底地形与检核点表现出良好的相关性;同时随着海深的增加,模型检核精度呈现不断升高的趋势。     

Comparative study of rock slope stability analysis methods for hydropower projects

This paper presents a comparative study of methods used for the analysis of the stability of rock slopes for hydropower projects. The comparison concerns the application of the limit equilibrium method, the block element method, and the finite element method on the stability analysis of two hydropower engineering projects in China. The study results show that the limit equilibrium method and the block element method give very close result, while the finite element method gives more conservative safety factor.     

Comparative analysis of chaos control methods: A mechanical system case study

Chaos may be exploited in order to design dynamical systems that may quickly react to some new situation, changing conditions and their response. In this regard, the idea that chaotic behavior may be controlled by small perturbations allows this kind of behavior to be desirable in different applications. This paper presents an overview of chaos control methods classified as follows: OGY methods - include discrete and semi-continuous approaches; multiparameter methods - also include discrete and semi-continuous approaches; and time-delayed feedback methods that are continuous approaches. These methods are employed in order to stabilize some desired UPOs establishing a comparative analysis of all methods. Essentially, a control rule is of concern and each controller needs to follow this rule. Noisy time series is treated establishing a robustness analysis of control methods. The main goal is to present a comparative analysis of the capability of each chaos control method to stabilize a desired UPO.     

Pile analysis by simple integral equation methods

Two simple integral equation methods are proposed for the analysis of vertical loaded pile. One of them is; let the axisymmetrical loads formed by Mindlin's horizontal point forces be distributed along the axis z in [0, L] of the elastic half-space, and composed with the Boussinesq's point force. The other is: in addition to the above fictitious loads, the. Mindlin's vertical forces are distributed along the axis z in [0, L]. The former reduces the problem of a vertical loaded pile embedded in a half-space with the following boundary conditions.     

Comparative analysis of methods of areal flooding of stratified reservoirs of anomalous oil

When anomalous oils in productive reservoirs are displaced by water [1], residual undisplaced oil remains [2, 3]. For calculating the volume of the unrecovered oil, most studies have been of homogeneous reservoirs [4–8]. In the present paper, the residual volume is assessed using an inhomogeneous-stratified-model. The inhomogeneity of the strata is described by the random distributions of Weibull or Pearson (gamma-distribution), which are characteristic of oilfields possessing anomalous properties (see, for example, [9]). A parametric study is made of four known schemes of areal flooding: two-point (straight line), five-, seven-, and nine-point [10]. The obtained estimates of the volume of the residual oil can be used for rational selection of the parameters for exploiting anomalous oilfields.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 121–126, May–June, 1985.     

Comparative study on underwater manipulation methods for valve-turning operation

Meccanica - The need for development of underwater vehicle-manipulator systems (UVMS) is on the rise owing to the increased requirement for underwater operations. To perform handle valve turning...     

Strain analysis of composites by moiré methods

Moiré techniques were developed, adapted and applied to the determination of strain fields in filamentary composite laminates. Conventional techniques, using 1000 line-per-inch (Ipi) arrays bonded or photoprinted onto the specimen, were applied to glass-epoxy and boron-epoxy specimens with holes and cracks. Techniques for tenfold fringe multiplication were also applied to glass-epoxy and boron-epoxy laminates with holes. A reflective surface of glass-like smoothness was produced on the specimen and a 500 dot-per-inch grid photoprinted on it. A rigid distortion-free camera was used for recording replicas of the specimen grid by projection photography. These replicas were analyzed with a 200 line-per-millimeter (5080 Ipi) grating for reconstruction of moiré-fringe patterns. These patterns were analyzed by graphical and mechanical differentiation using second-order moiré. Strain distributions and strain-concentration factors were in very good agreement with theoretical and other experimental results.