在Stuttgart（斯图加特）大学Morsch教授的领导下起草了第一套钢筋混凝土的建筑规范，并于1904年在Prussia（普鲁士）发布。1907-1909年在英国、法国、奥地利和瑞士发布了设计规范。 Building Codes 建筑规范
The American Railway Engineering Association（协会） appointed（任命）a Committee on Masonry（砌体委员会）in 1890. In 1903 this committee presented（提出）specifications for Portland cement concrete. Between 1908 and 1910 a series of committee reports led to the Standard Building Regulations for the Use of Reinforced Concrete published（发表）in 1910 by the National（国家的）Association of Cement Users（用户）which subsequently（随后）became the American Concrete Institute（协会）.
美国的铁路工程协会在1890年任命了一个砌体委员会。该委员会在1903年提出了波特兰水泥混凝土的规范。1908-1910间，一些列的委员会报告使国家水泥用户协会在1910年发表了钢筋混凝土使用的标准建筑规范，其随后成为美国混凝土协会。
A Joint Committee（联合委员会）on Concrete and Reinforced Concrete was established in 1904 by the American Society of Civil Engineers（土木工程师协会）, American Society for Testing and Materials, the American Railway Engineering Association, and the Association of American Portland Cement Manufactures. This group was later joined by（加入）the American Concrete Institute. Between 1904 and 1910 the Joint Committee carried out research. A preliminary （初步的）report issued in 1913 lists the more important papers and books on reinforced concrete published（发表）between 1898 and 1911. The final report of this committee was published in 1916. The history of reinforced concrete building codes in the United States was reviewed（回顾）in 1954 by Kerekes and Reid.
水泥与钢筋混凝土的联合委员会于1904年建立，包括美国土木工程师协会、美国测试和材料协会、美国铁路工程协会和美国波特兰水泥制造协会。该团体中后来又加入了美国混凝土协会。在1904-1910年间，联合委员会进行了研究。在1913年发布的初步报告中列出了在1898-1911年间发表的关于钢筋混凝土的较重要的文件和书籍。该委员会最后的报告发表于1916。Kerekes and Reid在1954对钢筋混凝土建筑规范在美国的发展历史作了回顾。
The design and construction of buildings is regulated（控制）by municipal bylaws（市政细则）called building codes. These exist to protect（用以保护）the public health and safety. Each city and town is free to（允许）write（编制）or adopt its own building code, and in that city or town, only that particular code has legal status（合法地位）. Because of the complexity of building code writing, cities in the United States generally base their building codes on one of three model（典型）codes: the Uniform（统一）Building Code, the Standard Building Code, or the Basic Building Code. These codes cover（包括） such things as use and occupancy requirements, fire requirements, heating and ventilating（供热和通风） requirements, and structural design. 建筑的设计和施工是由称为建筑规范的市政细则来控制的。这些规范是用以保护公众的健康和安全。每个城市和城镇允许编制或采用其自己的建筑规范，并且在那个城市或城镇只有那个特定的规范才有合法的地位。由于建筑规范编制的复杂性，美国的城市通常将它们的建筑规范以三个典型规范中的一个为基础，即统一建筑规范、标准建筑规范或基本建筑规范。这些规范包括诸如使用和居住的要求，防火要求、供热和通风要求以及结构的设计。
The definitive（最终的）design specification for reinforced concrete buildings in North America（北美）is the Building Code Requirements for Reinforced Concrete (ACI-318-95), which is
explained in a Commentary（说明）.
在北美，钢筋混凝土建筑最终的设计规范是钢筋混凝土建筑规范要求（ACI-318-95），并通过说明（对该规范要求）加以解释。
This code, generally referred to as （指..） the ACI Code, has been incorporated（体现）in most building codes in the United States and serves as the basis for comparable codes in Canada, New Zealand, Australia, and parts of Latin America. The ACI Code has legal status only if（只要）adopted in a local（当地的）building code. 该规范通常称为ACI规范，它已经在美国的大多数建筑规范中被体现，并作为加拿大、新西兰、澳大利亚和部分拉丁美洲国家类似规范的基础。ACI规范只要在当地的建筑规范中被使用便拥有合法的地位。
The rules for the design of concrete highway bridges（公路桥） are specified in the Standard Specifications for Highway Bridges, American Association of State Highway and Transportation Officials（美国国家公路和运输官方协会）, Washington, D.C.（哥伦比亚华盛顿特区）. 混凝土公路桥的设计规则在哥伦比亚华盛顿特区的美国国家公路和运输官方协会对公路桥的标准规范中作了规定。 Each nation or group of（一群）nations in Europe has its own building code for reinforced concrete. The CEB-FIP Model Code for Concrete Structures is intended to（用来）serve as the basis for future attempts to unify（统一）European codes. This code and the ACI Code are similar in many ways. 在欧洲每个国家或一群国家都有自己的钢筋混凝土建筑规范。混凝土结构的典型规范CEB-FIP被用来作为将来尝试统一欧洲规范的基础。该规范在很多方面与ACI规范是相似的。 作业练习
通过一篇Reading Material的学习，进一步了解混凝土作为结构材料的历史发展情况。
Unit 8 第八单元
Columns: Combined Axial Load and Bending 柱：轴向力与弯曲的组合 教学目标
了解柱子中箍筋的布置特点 了解相关图的确定和使用
了解短柱设计中的注意问题
熟悉钢筋混凝土柱子中的专业词汇 熟悉科技类文献中的常用句型
熟悉tie、spiral、stirrup的区别；limit、restrain、confine、hold的用法；refer to、be referred to、be referred to as 的区别；a family of、a series of、 a portion of 、great majority of的区别。 A column is a vertical structural member transmitting axial compressive loads（压缩荷载）, with or without moments. The cross-sectional dimensions of a column are generally considerably less than（远小于）its height. Columns support vertical loads from the floors and roof and transmit these loads to the foundations.
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 seismic regions the ties are heavier（较粗）and much more closely spaced（密集）. Spiral columns are used more extensively in such region. In a spiral column, the lateral expansion of the concrete inside the spiral (referred to as the core) is restrained by the spiral. 在地震区箍筋较粗且密集得多。螺旋箍筋柱较广泛地用于这样的地区（即地震区）。在螺旋箍筋柱中，螺旋箍筋内部的混凝土（称为核心）的横向扩张受到螺旋箍筋的约束。
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.
