capacity, If the soil is weak and/or column loads are great, the required footing areas become so large as to be uneconomical. In this case, unless a deep foundation is called for by soil conditions, a mat or raft foundation is resorted to. This consists of a solid reinforced-concrete slab which extends under the entire building and which consequently distributes the load of the structure over the maximum available area. Such a foundation, in view of its own rigidity, also minimizes differential settlement. It consists, in its simplest form, of a concrete slab reinforced in both directions. A form which provides more rigidity and at the same time is often more economical consists of an inverted beam-and-girder floor. Girders are located in the column lines in one direction, with beams in the other, mostly at closer intervals. If the columns are arranged in a square pattern, girders are equally spaced in both directions and the slab is provided with two-way reinforcement. Inverted flat slabs, with capitals at the bottoms of the columns, are also used for mat foundations.
一些独立或联合的柱基是扩展基础中具有理想承载力的最常用形式。如果土层比较柔软或者柱上的荷载很大，基础面积将会变得非常大，变得不经济。碰到这种情况，考虑到土层，除了使用深基础外，还可以考虑使用垫层或者筏基。它们由实心的钢筋混凝土板构成，并且延伸到整个建筑底部，因此可以将基础的荷载分布到最大可用的区域。这种基础，从其自身的刚度来讲，也可以减小不均匀沉降。这是一种最简单的形式，它在两个方向都配有混凝土板和钢筋， 这种形式通
过使用倒梁和肋梁楼板，能够提供更大的刚度，从而更经济。主梁通常沿柱中线同方向布置，次梁则布置在同一个方向，且距离较近。 如果柱允许做成方形，则主梁可沿两个方向等距离放置，同时板也可以双向布置。用于柱底部的无梁楼盖，则常用于筏板基础。
[6]On compressible soils footings should be loaded concentrically to avoid tilting, which will result if bearing pressures are significantly larger under one side of the footing than under the opposite side. This means that single footing should be placed concentrically. under. The columns and wall footings concentrically under the walls and that for combined footings the centroid of the footings area should coincide with the resultant of the column loads. Eccentrically loaded footings can be used on highly compacted soils and on rock. It follows that one should count on rotational restraint of the column by a single footing only when such favorable soil conditions are present and when the footing is designed both for the column load and the restraining moment. Even then, less than full fixity should be assumed, except for footings on rock.
在可压缩土中，基础应居中放置，避免倾斜，否则会导致一侧的压力比另一侧的压力大很多。这意味着，独立基础在住下方应居中放置，墙基础在墙下方应居中放置，对于联合基础来说，整个基础的重心应与柱荷载重心重合。承受偏心荷载的基础常用于密实性好的土壤及岩石上接下来应该考虑独立基础位于合适土层中时以及基础设计用来承受柱荷载和约束力矩时柱中的转动约束问题，尽管如此，也不能假
定完全牢固，除非基础坐落在岩石上。
第十一单元 [2]Long-span structures cannot be designed any more like any other building type because of their vulnerability to failure. 由于大跨结构极易损坏，因此不能像其他结构类型一样进行设计。 [3]The larger scale may require building contigurations quite different from traditional forms as well as other materials and nonconventional detailing techniques. It requires a more precise evaluation of loading conditions than just provided by codes, this includes the placement of expansion joints as well as the inclusion of secondary stresses due to the deformations of the members and their interaction, which cannot be ignored any more as for small-scale buildings or structures of high redundancy. Further, it requires a much more comprehensive field inspection to control the quality during the erection phase, post-construction building maintenance and periodic inspection is necessary to monitor the effects of loading and weather on member behavior in addition to the potential deterioration of the materials. 由于大跨结构极易损坏，因此不能像其他结构类型一样进行设计。大型结构可能需要特殊的建筑构型，这和传统方式、材料和非常规的技术不同。它需要提供比规范要求的更精确地荷载条件，其中包括伸缩缝（接头）的位置，以及由于构件变形及相互作用所产生的二次应力，然而，对于高冗余的小型建筑或结构所产生的二次应力也不能忽视。而且，还需要进行更全面的现场检查来控制其在安装阶段的质量，对于后减建筑的维护与定期检查也是必须的，这样不仅能监测材料本身潜在的失效问题，还能监测荷载与气候对构件所构成的影响。
[8]Each of the cantilevering masses is supported by its side walls, which in turn act as vertical, cantilevers with respect to gravity action. The continuous wall-roof space truss envelope of case (Fig.11-8)is only edge supported at three locations, it allows a column-free interior space and flexibility in the placement of openings and large overhangs.
每个悬臂实体由它的侧墙支撑着，侧墙反过来可以作为竖向的，承受重力作用的悬臂结构。（图11-8）连续的屋面网架结构只在三个方向的边缘进行了支撑，这就提供了一个无中柱的室内空间，并给开敞及大悬挑结构的布置带来了灵活性。
词组optimum design 最优设计 transit-mixed 混合运输 field-or-job-mixed 现场或临时 with respect to 有关关于 retaining walls 挡土墙 sign off 签字 in conjunction with 连同，同…连起来
钢构件容许（allowable）长细比 allowable slenderness of steel member .裂缝宽度容许值 allowable value of crack with
超固结土 over consolidated soil 饱和度 saturation level 最优含水量 the optimum moisture 渗透系数 saturation coefficient 恒载持续荷载 constant load 有限元法 finite element method 地基承载力 bearing strength of the ground 最终沉降 final settlement
rolling hinge 滚动铰 Have recourse to 求助于，依靠 In contradiction to同…..相矛盾
Deep foundation excavation 深基坑开挖 Column bracing 柱间支撑
Cold bend inspection of steel bar 钢筋冷弯检查 Compression member with small 小偏心受压柱 Creep of concrete 混凝土徐变
engineering essentials 工程实际 building/architectural form 建筑风格 strength and stiffness 强度和刚度 unbalanced force 不平衡力 factor of safety 安全系数 anticipate load 预计荷载 material property 材料特性 structural system 结构体系 linear function 线性功能 fire-resistant 防火
high-rise frame 高层框架 apparent safety 外观安全性conglomerate stone 组合石材 coarse aggregate粗骨料 stone concrete 碎石混凝土 lightweight concrete轻质混凝土 compressive material抗压材料 tensile strength 抗拉强度
可能考选词填空
Shear stresses in pairs act on an element at or near the wide surface, as shown in Fig. 4-4a, As shown in strength of materials , this state of stress corresponds to equal tension and compression stresses on the faces of an element at 45°to the direction of shear . These inclined tension stresses are of the same kind as those cause by transverse shear .However, in the case of torsion, since the torsional shear stresses are of opposite signs in the two halves of the member(Fig.4-4b)the corresponding diagonal tension stresses in the two halves are at right angles to each other(Fig.4-4a). When the diagonal tension stresses exceed the tension resistance of the concrete, a crack forms at some accidentally weaker location and spreads immediately across the beam, as shown in Fig.4-5,Observation shows that the tension crack(on the near face on Fig.4-5b) forms at practically 45°,that is, perpendicular to the diagonal tension stresses. The cracks on the two narrow faces, where diagonal tension stresses are smaller, are of more indefinite inclination, as shown, and the fracture line on the far face connects the cracks at the short faces. This completes the formation of an entire fracture surface across the beam which fails the member.