柱是竖向的结构构件，传递轴向压缩荷载和弯矩（或无弯矩）。柱的横截面尺寸通常远远小于其高度。柱子支承着来自楼面和屋面的竖向荷载，并将它们传于地基。
           In construction, the reinforcement and concrete for the beams and slabs in a floor are placed. Once this concrete has hardened, the reinforcement and concrete for the columns over that floor are placed, followed（接着）by the next-higher floor（下一个更高楼面）.

            施工时，将楼面梁和楼面板的钢筋与混凝土放入。一旦混凝土已经变硬，则将该层柱子的钢筋和混凝土放入，紧接着进行下一个更高楼面的（施工）。
           The more general terms（通用的术语）compression members or members subjected to combined axial load and bending are sometimes used to refer to（指、表示）columns, walls, and members in concrete trusses or frames. These may be vertical（垂直的）, inclined（倾斜的）, or horizontal（水平的）. A column is a special case（特殊的例子）of a compression member that is vertical.

            有时采用较通用的术语即受压构件或承受轴向力和弯曲组合的构件来表示柱子、墙和混凝土桁架或框架中的构件。这些构件可以是垂直的、倾斜的或水平的。柱子是受压构件中一种特殊的例子，即垂直的。
        Stability effects（影响）must be considered in the design of compression members. If the moments induced（引起）by slenderness effects（细长度效应）weaken a column appreciably（明显地）, it is referred to as a slender column or a long column. The great majority of（绝大多数的）concrete columns are sufficiently stocky（非常粗短的）that slenderness can be ignored. Such columns are referred to as short columns.
            在设计受压构件时必须考虑稳定性的影响。如果由于细长度效应引起的弯矩明显地削弱了柱子，它被称为细长柱或长柱。绝大多数的混凝土柱子是非常粗短的，以致可以忽略其细长度。这样的柱子称为短柱。
             Tied and Spiral Columns
普通箍筋和螺旋箍筋的柱子

Over（超过）95% of all columns in buildings in nonseismic regions（非地震区）are tied columns. Tied columns may be square（正方形）, rectangular, L shaped, circular, or any other required shape. Occasionally when high strength and/or high ductility（延性）are required, the bars are placed in a circle（圆环）and the ties are replaced by a bar bent into a helix or spiral（螺旋线）, with a pitch（间距）of 1.375 to 3.375 in.（英寸）. Such a column is called a spiral column. Spiral columns are generally circular, although square or polygonal（多边形）shapes are sometimes used. The spiral acts to restrain the lateral expansion（横向扩张）of the column core under axial loads causing crushing（压碎）, and in doing so, delays（延缓）the failure of the core, making the column more ductile.
            在非地震区域的建筑物中超过95%的柱子是普通箍筋的柱子。普通箍筋的柱子可以是正方形、矩形、L形、圆形或其它任何需要的形状。偶尔当需要高强度和/或高延性时，将钢筋置入一个圆环，普通箍筋由弯成螺旋线的钢筋代替，间距为1.375-3.375英寸。该柱子称为螺旋箍筋柱。螺旋箍筋柱通常是圆形的，尽管有时也用正方形或多边形。螺旋箍筋的作用是约束柱子的核心在导致压碎的轴向荷载作用下的横向扩张，并据此延缓其核心的破坏，使柱子具有更好的延性。
          In a tied column in a nonseismic region, the ties are spaced roughly（约）the width of the column apart（间隔为）, and as a result, provide relatively little lateral restraint to the core. Outward（向外的）pressure on the sides of the ties due to lateral expansion of the core merely（仅仅）bends them outward, developing a negligible（可忽略的） hoop stress effect（环向应力效应）. Hence normal（普通）ties have little effect on the strength of the core in a tied column. They do, however, act to reduce the unsupported length of the longitudinal bars, thus reducing the danger of buckling（屈曲）of those bars as the bar stress approaches yield.
            在非地震区的普通箍筋柱中，普通箍筋相隔的间距约为柱子的宽度，因此对核心混凝土提供了比较小的横向约束。由于核心（混凝土）的横向扩张导致普通箍筋边上向外的压力仅使普通箍筋向外弯曲，形成一个可忽略的环向应力效应。因此，在普通箍筋柱中，普通的箍筋对核心混凝土的强度几乎没什么影响。但是它们减少了纵向钢筋未被支撑的长度，这样当钢筋的应力接近屈服时可减少这些钢筋发生屈曲的危险。
         When the shell（外壳）spalls off（剥落）the spiral column, the column does not fail immediately because the strength of the core has been enhanced（加强）by the triaxial stresses resulting from the effect of the spiral reinforcement（加强）. As a result, the column can undergo large deformations, eventually reaching a second（另一个）maximum load when the spirals yield and the column finally collapses. Such a failure is much more ductile and gives warning of the impending（即将发生的） failure together with possible load redistribution（重分布）to other members. It should be noted, however, that this is accomplished（实现）only at very high strains. For example, the strains necessary to reach the second（第二个）maximum load correspond to a shortening of about 1 in. in  an 8-ft-high column. When spiral columns are eccentrically（偏心）loaded, the second maximum load may be less than the initial maximum, but the deformations at failure are still large, allowing load redistribution.