-
4PART 2Analysis and design of structural elements In the nine chapters in Part II we systematically treat all the major structural elements used building context. Each chapter contains initial sections that define the element and discuss in tributes in a qualitative way. The following sections present more detailed analysis of the structural characteristics of the element and discuss principles that are useful in a design .30111
- 上一篇：气压管道模型受不稳定剪力的裂纹扩展英文文献和中文翻译
- 下一篇：冷轧机的发展英文文献和中文翻译
As discussed in more detail in Part III, design endeavors may be classified into first second-, and third-order activities, generally characterizing the sequence in which design are encountered and must be made. First- and second-order activities deal with establish relations between broader design intents, specific morphological characteristics of the building and the type and attributes of different structural systems (materials, systems, structural chies, bay geometries). Third-order activities focus on member and connection design within constraints previously established by earlier decisions. It is in the latter sense that the term is used in Part II. A thorough knowledge of the analysis and design of such members as cables, beams, columns, trusses, frames, plates, shells, and membranes is a necessary to understanding first- and second-order design activities, and for this reason the analysis design of elements are discussed first, even though the design process does not proceed in sequence.
Chapter 4
Trusses
Although structures made of jointed members have been constructed throughout history, the conscious exploitation of structural advantages inherent when inpidual linear members are formed into triangulated patterns is of relatively recent origin. Structures of this type, commonly called trusses, were indeed built quite early. Simple trusses using relatively few members often appeared in common pitched roofs. More complex trusses were used in isolated instances. A bridge using a form of timber truss, for example ,however, had little significant impact on the methods of building of the time. The Italian architect Andrea Palladio(1518-1580) gave an illustration of a correctly triangulated truss structure and indicated that he had some knowledge of its potential and the way it carried forces. Trusses were occasionally used afterward in large public buildings such as Independence Hall, Philadelphia, but again without having much impact as a structural innovation. It was the bridge builders of the early nineteenth century who first began systematically to explore and experiment with the potential of the truss. This was in response to the demands of rapidly expanding transportation systems of the time. Emiland Gauthey’s Traite de la Construction des Ponts(posthumously published between 1809 and 1813 by his nephew, the famous mathematician Louis Navier of the Ecole Polytechnic in Paris),provided a foundation for many subsequent theoretical works in the area. Gauthey’s treatise include a discussion of what he termed the principles of equilibrium of position and equilibrium of resistance. The former was an initial attempt to resolve bridge loads into components in inpidual members. The latter dealt with material properties and the sizing of truss members. Later important contributions include Squire Whipple's classic of structural engineering, A Work on Bridge Building, published in 1847. The development of the truss was thus fostered by a tentative but rapidly expanding body of theoretical knowledge. This contrasts with other structural forms which typically developed slowly over time in a strictly empirical way. The truss soon became a common structural form used in civil engineering structures spanning long distances. The use of trusses in buildings also increased, although more slowly due to different traditions and needs, until they became a common element in modern architecture. The emergence of the truss as a major structural form has been rapid and its impact significant. The remainder of this chapter explores what a truss is, how it works, and why it is an important structural form. The presentation is an inquiry into a specific structural element. On amore general level, the methods of analysis and design presented for trusses are used to demonstrate principles that are broadly applicable to the analysis and design of a wide range of other structural forms.