10外文文献翻译

1、第 PAGE 126 页外文翻译Web Yielding and Web CripplingCome from Applied Structural Steel Design (Fourth Edition)，TSINGHUA UNIVERSITY PRESS.A beam that is subjected to concentrated loads applied normal to the flanges and symmetric to the web must be checked to ensure that a localized failure of the web does

2、not occur. The ASDS, Section Kl, establishes requirements for beam webs under compression due to concentrated loads. When the stipulated requirements are exceeded, the webs of the beams should be reinforced or the length of bearing increased.Two conditions are considered: web yielding and web crippl

3、ing. Figure 4-25 illustrates the type of deformation failure expected. Practical and commonly used bearing lengths N are usually large enough to prevent this type of failure from occurring.With respect to web yielding, the ASDS, Section K1.3, requires that the compressive stress at the toe of the fi

4、llet, shown in Figure 4-26, not exceed 0.66 .The assumption is made that the load spreads out so that the critical area for stress, which occurs at the toe of the fillet, has a length of (N + 2.5k) or (N + 5k) for end reactions and interior loads, respectively, and a width of . The dimension k, whic

5、h locates the toe of the fillet, is tabulated for various shapes in the ASDM, Part 1.The controlling equations for web yielding are as follows:1. For interior loads (defined as applied at a distance from the end of the member that is greater than the depth d of the member), ASDS Eq.(K1-2)FIGURE4-25

6、Web yielding/web crippling2. For end reactions, ASDS Eq.(K1-2)where R is the applied concentrated load and N is the length of bearing.Should the web yielding stress be excessive, the problem may be corrected by increasing the bearing length ,by designing bearing stiffeners (discussed in Section 5-6

7、of this test), or by selecting a beam with a thicker web.With respect to web crippling , the ASDS , SectionK1, places limits on the compressive concentrated loads.For interior loads (defined as applied at a distance from the end of the member that is greater than d/2 ),the limiting load R may be tak

8、en as ASDS Eq.(K1-4)FIGURE4-26 Web yieldingFor end reactions, ASDS Eq.(K1-5)where=maximum concentrated load or reaction (kips)=specified minimum yield stress of beam web (ksi)And all other terms are previously defined.For unreinforced webs, both web yielding and web crippling should be checked under

9、 all concentrated loads and at points where the beam is supported by walls or pedestals or at columns when the connection is a seated type. If web stiffeners are provided and extend at least one-half the web depth, Equations (K1-4) and (K1-5) need not be checked.A third type of failure considered in

10、 the ASDS, Section K1.5, is termed sidesway web buckling. This phenomenon manifests itself in the lateral buckling of the tension flange due to compression in the web that results from the application of concentrated load on the compression flange of the beam. Sidesway web buckling can be prevented

11、by the use of lateral bracing or stiffeners at the concentrated load point. This type of failure is further discussed with regard to plate girders in Section 5-6 of this text.Example 4-16A W24 x 55 beam of A36 steel has an end reaction of 70 kips and is supported on a plate such that N = 6 in. (see

12、Figure 4-26).the beam for web yielding and web crippling.Solution:For this shape,Check web yielding using Equation (K1-3) for end reactions. The compressive stress at the toe of the fillet isThe web yielding allowable stress isCheck web crippling using Equation (K1-5) for end reactions.The maximum c

13、ompressive force isSince 55 kips70 kips, the beam is inadequate with respect to web crippling. Bearing stiffeners must be provided, or the length of bearing must be increased.Note that the web yielding equationsASDS Equations (K1-2) and (K1-3) may be expressed in different forms. To determine allowa

14、ble load (based on allowable web yielding stress):For end reactions,For interior loads,To determine minimum length of bearing required (based on allowable web yielding stress):For end reactions,For interior loads,Rather than use the web yielding and web crippling equations as previously described, t

15、his checking process can be significantly simplified by using the ASDM, Part 2, Allowable Uniform Load Tables. The data furnished in the tables are summarized as follows:The tabulated value R (kips) is the maximum end reaction for 3 in.of bearing length (N = 3in.) For other values of N, the maximum

16、end reaction with respect to web yielding is computed from where andare constants tabulated for each shape in the Allowable Uniform Load Tables.2. In a similar manner the maximum end reaction with respect to web crippling is computed fromwhereand are also tabulated constants.Using the tabular values

17、 greatly simplifies the calculations involving web yielding and web crippling.Example 4-17Rework Example 4-16 by using the tabulated values to determine the maximum end reaction and compare with the end reaction of 70 kips.Solution:From the Allowable Uniform Load Tables, for the W2455 of A36 steel,

18、for a bearing length N of 6 in., the maximum end reaction is computed with respect to web yielding and web crippling.Web yielding: Web crippling: The beam is not satisfactory with respect to web crippling. This checks Example 4-16.腹板屈服和腹板压跛一个受到集中荷载的梁采用普通的翼缘和对称的腹板，必须进行检查，以确保翼缘不会发生局部破坏。ASDS的K1节，设定在集中载

19、荷作用下梁腹板受压条件。当超过规定要求，腹板梁应进行加固或增加大支承长度。需要考虑的两种情况：腹板屈服和腹板压跛。图4 - 25说明了的变形破坏的预期类型。实际的和常用的支承长度通常是大到足以防止此类破坏的发生。关于腹板屈服，ASDS,K1-3部分，要求如图426所示角焊缝的焊趾边界的压应力，不超过0.66。假定荷载传递使出角焊缝焊趾边界产生应力的临界面，分别有一个长度为（N+2.5k）或（N+5k）的最终反应和内部荷载，以及一个宽度。规定了角焊缝焊趾位置的尺寸k，在ASDS第一部分被定义为各种形式。腹板屈服的控制方程如下：1.内部荷载（定义为与构件端部的距离大于构件深度的荷载） ASDS E

20、q.(K1-2)图4-25 腹板屈服和腹板压跛2.最终反应 ASDS Eq.(K1-2)这里R是作用的集中荷载，N是轴线长度。一旦腹板的屈服应力过高，可以通过增加轴线的长度，设计支承加劲肋（5-6节中讨论这一实验），或者选择更厚的腹板。对腹板压跛，ASDS的K1节，限制了压缩集中荷载1.内部荷载（定义为与构建末端的距离大于d/2的荷载），极限荷载R可取为 ASDS Eq.(K1-4)图4-26 腹板屈服2.最终反应 ASDS Eq.(K1-5)这里R-最大集中荷载或反应（磅）-规定梁腹板的最小屈服应力其他方面同以前定义对未加强腹板，在全集中荷载并且梁被墙或支座或柱支撑的一些类型为坐式时应检测腹板屈服和腹板压跛。如果腹板加劲肋和扩大提供至少有一半的腹板深度，方程（k1-4）和（k1-5）不需要进行检查。ASDS中K1.5节第三种类型的破坏称为侧移腹板屈曲。这种现象体现了其自身由于作用于梁受压翼缘集中荷