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61.
T.A. Wyatt 《Journal of Wind Engineering & Industrial Aerodynamics》2004,92(5):359-374
The classical spectral analysis of structural response to a gusty wind is applied to the prediction of fatigue damage as expressed by the rate of accumulation of Miner's quotient, using the rainflow algorithm to establish stress-range cycle counts. A general solution in chart form is given for the effect of the broad-band (quasi-static) part of the response spectrum, together with an algebraic formulation for its combination with the effect of narrow-band (quasi-resonant) response.A procedure for integration of the long-term expectation of Miner's quotient is indicated. It is concluded that quasi-static response alone is unlikely to pose a serious fatigue problem. With generally anticipated levels of dynamic response, fatigue damage is greatly increased, but can be controlled at acceptable levels by care to avoid features especially sensitive to fatigue. 相似文献
62.
也谈轻型钢结构房屋柱基设计 总被引:1,自引:1,他引:0
对柱脚抗剪键的设置和计算中所取用的荷载组合提出个人观点,同时对轻钢结构柱脚螺栓受拉计算提出注意事项. 相似文献
63.
Ed Lowry 《Computer Standards & Interfaces》1991,13(1-3):105-108
Maximizing the satisfaction of a value in an engineering design is usually limited by tradeoffs in which other values become unacceptably sacrificed. In a few cases, however, the maximization is limited by a boundary between what is mathematically possible and what is not. Round wheels, vertical pillars, and binary memory elements are examples of optimum engineering structures which result from such mathematical limits. It is proposed that optimum characteristics of a language data model result similarly by minimizing the variety of primitive data objects, the complexity of those objects, and the number of objects needed to represent data states. Reducing these measures is needed to combine both rich data structure and powerful operations in one language. The minimizations lead to a narrow range of designs for language semantics in which the potential advantages of specialization is small compared with the advantages of commonality. Universal language for support of technical literacy appears to be an appropriate scope of generality in language design. 相似文献
64.
Service Load Effective Compression Flange Width in Fiber Reinforced Polymer Deck Systems Acting Compositely with Steel Stringers 总被引:1,自引:0,他引:1
This paper reports on the field study of a steel stringer-fiber reinforced polymer (FRP) deck composite bridge in Pennsylvania. The objective of the study is to assess the effective compression flange width in the FRP deck and floor systems when they act compositely with underlying steel girders at service conditions. The research results reported herein support the notion of employing a design approach, for both interior and exterior girders of a composite floor system, that is philosophically consistent with current practice related to steel girders acting compositely with concrete decking. It appears from the results presented herein that FRP decks and floors acting compositely with underlying steel girders exhibit an effective width that is close to the actual girder spacing for interior beams, and approximately one-half this value for exterior beams. 相似文献
65.
Design optimization of 3D steel structures: Genetic algorithms vs. classical techniques 总被引:1,自引:0,他引:1
María Belén Prendes Gero Antonio Bello García 《Journal of Constructional Steel Research》2006,62(12):1303-1309
In this paper an elitist genetic algorithm (GA) developed by the authors is compared with common commercial solutions for complex structural optimization. After its prior validation on two-dimensional (2D) structures, the GA was tuned and improved in order to obtain structural elements with minimum weights that satisfy the ultimate limit states of the applicable building code. Subsequently, the same spatial structures were optimized using a commercial structural analysis program. Finally, the cost and weight improvements obtained using the GA, although at a higher computational cost, are discussed. 相似文献
66.
通过典型示例揭示了传统杆系结构虚功原理在“微小位移”假定下,忽略挠度的一阶导数,用二阶导数代替曲率,造成的近似计算的假象,以及引起的概念上的混乱. 论证了虚功原理实质上是一组精确的数学恒等式,只是通过定义“力”和“位移”使其中每一项都赋予了虚功的物理意义,并不存在近似的问题. 提出了用截面转角的正切值定义截面的转动位移,并将虚功中力和位移的关系描述为力不随位移拖动的模式. 由此澄清了传统虚功原理可能引起的“近似计算,只适用于小位移”的假象,使虚功原理可以抛弃小位移假定,精确地适用于大位移情形. 相似文献
67.
68.
Wolfgang Appelt 《Computer Standards & Interfaces》1988,7(4):377-385
The Office Document Architecture (ODA) is an International Standard which is developed by TC 97/sc 18 of the International Organization for Standardization (ISO) in close collaboration with CCITT's Study Group VIII and with ECMA. This paper describes the current state of a formal specification of the ODA document structures by mathematical means and its use for conformance specification and conformance testing. 相似文献
69.
建筑结构爆破震动效应及安全分析研究 总被引:19,自引:8,他引:11
从现代爆破作用原理出发。对岩体爆破的振动特性,影响因素及最新研究进展作了综合评述。并通过大量科研观测资料分析。结合我国某些工程实践经验。着重介绍了岩土爆破对闸坝工程,水工隧洞的作用特性。破坏机制和安全准则。 相似文献
70.
Yangjun Chen 《Information Processing Letters》2006,99(1):19-26
A precise analysis of the retrieval of signature trees is presented. A signature tree is a data structure constructed over a signature file to speed up searching all those signatures, which match a given query signature. The methods used include a detailed study of probabilistic analysis in conjunction with suitable contour integration of complex variabled functions. 相似文献