有关建筑结构的外文翻译.doc

Types and function of substructure, or foundation, is that part of a structure which is usually placed below the surface of the ground and which transmits the load to the underlying soil or rock. All soils compress noticeably when loaded and cause the supported structure to settle. The two essential requirements in the design of foundations are that the total settlement of the structure shall be limited to a tolerably small amount and that differential settlement of the various parts of the structure shall be eliminated as nearly as possible. With respect to possible structural damage, the elimination of differential settlement, i.e., different amounts of settlement within the same structure, is even more important than limitations on uniform overall settlement.
To limit settlement as indicated, it is necessary to transmit the load of the structure to a soil stratum of sufficient strength and to spread the load cover a sufficiently large area of that stratum to minimize bearing pressure. If adequate soil is not found immediately below the structure, it becomes necessary to use deep foundations such as piles or caissons to transmit the load to deeper, firmer layers. If satisfactory soil directly underlies the structure, it is merely necessary to spread the load, by footings or other means. Such substructures are known as spread foundations, and it is mainly this type which will be discussed.
下部结构的类型和作用
下部结构（或称基础）通常是设置在地面以下、并将荷载传递给下面土壤或岩石的结构部分。所以土壤在受荷作用时明显受到压缩，并引起所支撑的建筑物沉降。在基础设计中有两个基本要求，一是结构总的沉降要限制到尽量小的程度，二是要尽可能消除结构物各部分的不均匀沉降。就建筑物被破坏的可能性而言，避免不均匀沉降，即避免同一建筑物的沉降差值比限制均匀的譆@两蹈匾Ⅻbr>为了限制上述沉降，必须把建筑物的荷载传递到有足够强度的土层，把荷载分布在该土层足够大的面积上，以减少支撑压力，如果建筑物下就近找不到合适的土层，必须采用深基础，例如桩或沉箱，以便把荷载传递到较深的坚实土层上，如果正好在建筑物的下面就有良好的土层，仅需要用基础或其他手段来扩散荷载。这样的荷载叫做扩展基础。
扩展基础的种类
基础通常分墙基础和 柱基础，墙基础只不过是比墙稍宽的钢筋混凝土条带，它分散墙体的压力，单柱基础通常是正方形，有时是长方形，都是最简单最经济的形式，如果地产权不允许基础突出外墙，外柱使用这种基础就会有麻烦，在这种情况下，可采用不突出墙柱以外的复式基础或条形基础，在间距小的重载内柱下可采用两柱或更多柱的复式基础，如果这种情况下采用单个基础，它们将完全连在一起。
在有较好承载能力的土层上，单个柱基或复式柱基是扩展基础的最常用形式，如果土质软或柱荷载大，需要的基础面积将太大而不符合经济要求，在这种情况下，除非根据土壤条件需要深基础，否则就采用板式基础，这种基础是铺