畢業(yè)設(shè)計(jì)外文翻譯----結(jié)構(gòu)分析-其他專業(yè)-資料下載頁
2025-01-19 04:18本頁面
【導(dǎo)讀】它與建筑風(fēng)格是不可分割的，在不同程度。如能巧妙地設(shè)計(jì)建筑結(jié)構(gòu)，則可建立或加強(qiáng)建筑空間與建筑平面。之間的格調(diào)與節(jié)奏。不幸的是在一些情況下，它不能被忽視，它是存在的。合理的形式提供了依據(jù)。在上述三項(xiàng)要求中，很明顯維持建筑物形狀的穩(wěn)定性要求是首選。構(gòu)意味著有不平衡的力或失去平衡狀態(tài)，并且會(huì)導(dǎo)致建筑結(jié)構(gòu)整體或部分產(chǎn)生加速度。強(qiáng)度的要求意味著材料的選擇要能抵抗荷載和變形引起的應(yīng)力。建筑物的功能相關(guān)而不應(yīng)該與建筑風(fēng)格相矛盾。很顯然，結(jié)構(gòu)體系必須能保持完整直到內(nèi)部人員安全撤離為止。建筑規(guī)范詳細(xì)規(guī)定了建筑物的某些部位抵抗熱量而不倒塌的時(shí)間。準(zhǔn)方法加以推廣，使之也可以在動(dòng)荷載的分析中加以應(yīng)用。動(dòng)荷載的一種特殊形式。同樣，在動(dòng)荷載下的結(jié)構(gòu)反應(yīng)，即所產(chǎn)生的撓度。何特定的結(jié)構(gòu)體系在非隨機(jī)動(dòng)荷載下的反應(yīng)分析通常定義為確定分析。
【正文】 in any given case depen ds upon how the loading is defined. If the time variation of loading is fully known, even though it may be highly oscillatory or irregular in character, it will be referred to herein as a prescribed dyn amic loading and the analysis of the response of any specified structural system to a prescribed dynamic loading is defined as a deterministic analysis. On the other hand,if the time variation is not pletely known but can be defined in a statistical sense, the loading is termed a random dynamic loading。 a nondeterministic analysis Correspondingly is the analysis of response to a random dyna mic loading. In general, the structural response to any dynamic loading is expressed basically in terms of the displacements of the structure. Thus a deterministic analysis leads to a displacementtime history corresponding to the prescribed loading history 。other aspects of the deterministic structural respo nse,such as stresses,strains,internal forces,etc. ,are usually obtained as a secondary phase of the ana lysis, from the previously established displacement patterns. On the other hand,a nondeterministic analysis provides statistical information about the displacements which result from a statistically de fined loading. In this case,the time variation of the displacements is not determined,and other aspec ts of the response,such as stresses,internal forces, etc. , must be evaluated directly by independent nondeterministic analysis rather than from the displacement results. A structuraldynamic problem differs from its staticloading counterpart in two important respe cts. The first difference to be noted, by definition, is the timevarying nature of the dynamic proble m. Because the load and the response vary with time,it is evident that a dynamic problem does not have a single solution,as a static problem does. Instead the analyst must establish a succession of so lutions corresponding to all times of interest in the response history. Thus a dynamic analysis is cle arly more plex and timeconsuming than a static analysis. 10 However,a more fundamental distinction between static and dynamic problems is illustrated in Fig. 1. If a simple beam is subjected to a static load p ,as shown in Fig. )(a , its internal mome nts and shears and deflected shape depend directly upon the given load and can be puted from p by established principles of force equilibrium. On the other hand, if the load )(tp is applied dy namically,as shown in Fig. )(b , the resulting displacements of the beam are associated with accelra tions which produce inertia forces resisting the accelerations. Thus the internal moments and shears in the beam in Fig. )(b must equilibrate not only the externally applied force but also the inertia fo rces resulting from the accelerations of the beam. P )(a )(tP Inertia forces )(b Fig. 1 Basic difference between static and dynamic loads: )(a static loading。 )(b dynamic loading Inertia forces which resist accelerations of the structure in this way are the most important disti nguishing characteristic of a structuraldynamics problem. In general, if the inertia forces represent a signifieant portion of the total load equilibrated by the internal elastic forces of the structure, then the dynamic character of the problem must be accounted for in its solution. On the other hand,if the motions are so slow that the inertia force39。s,are negligibly small, the analysis for any desired instant of time may be made by static structuralanalysis procedures even though the load and response ma y be timevarying.
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