毕业设计外文翻译--钢结构设计规范

毕业设计外文资料翻译

原文题目：钢结构设计规范 GB50017-2003 English

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译文题目：钢结构设计规范 GB50017-2003

院系名称：土木建筑学院专业班级：土木工程0901

附件： 1.外文资料翻译译文；2.外文原文。

附件1：外文资料翻译译文

钢结构设计规范 GB50017

3.4 设计指数

3.4.1钢的强度设计值应根据钢的厚度或者直径从表格3.4.1-1中查取。钢铸件的强度设计值应从3.4.1-2表格中查询。连接强度的设计值应该通过3.4.1-5从表格3.4.1-3中查取。

表3.4.1-1钢材强度设计值

备注：表中厚度表示计算点的钢材厚度，对于轴心力的作用主要是指截面中较厚的板件区域。

表3.4.1-2 钢铸件的强度设计值

备注：1.用于自动和半自动焊的焊条和焊剂应保证熔敷金属的力学性能不低于现行国家标准《埋弧焊用碳钢焊丝和焊剂》GB/T 5293和《低合金钢埋弧焊用焊剂》GB/T 12470中的相关规定。

2.焊缝的质量等级应符合现行国家标准《钢结构工程施工质量验收工程规范》GB 50205的规定。对厚度小于8mm的对接焊缝型的钢材不应采用超声波探伤来确定焊缝质量等级。

3.，在弯曲部分的对接焊缝，把fcw作为受压区的强度设计值，把ftw作为手拉去的强度设计值。

4，表中的厚度是指计算位置的钢材厚度，对于轴心受拉和轴心受压构件是指构件中较厚板件的厚度。

备注：1、A级螺栓用于螺栓的d=24mm或者l>=10d或l>=150mm（取较小值），d是公称直径，l是螺杆的公称长度。

2、A、B级螺栓孔的精度和孔壁表面的粗糙度，C级螺栓的允许偏差和孔壁表面的粗糙度应符合现行国家标准《钢结构工程施工质量验收工程规范》GB 50205的规定。

1、属于下列情况的为一类孔：

1）在装备好的构件上按设计要求的孔径钻成的孔； 2）在单个零件和构件上按设计要求用钻磨钻成的孔；

3）在单个零件上先钻成或者充成较小的孔径，然后在装配好的构件上扩钻成设计直径的孔。

2，在单个零件上一次冲成或不用钻模直接钻成的孔是二类孔。

3.4.2在下列情况的结构或者连接时，在条款3.4.1中规定的设计值应该乘以一个相应的折减系数。

1、单面连接的单角钢

1）按照轴心受力计算强度和连接，乘以系数0.85 2）按轴心受压构件计算稳定性

等边角钢乘以系数 0.6+0.0015a，但不大于1 以短边相连的不等边角钢连接，乘以系数 0.5+0.0025a，但不大

于1

以长边相连的不等边角钢相连，乘以系数 0.7

a表示细长比，对于一个中部没有连接的单角钢压杆，按最小的回

转半径计算，当a

2、无垫板的单面施焊对接焊缝，乘以系数 0.85

3、在地面以上的不利条件下的焊接和铆钉连接的构件，乘以系数 0.9 4、埋头孔和半埋头孔的铆钉连接乘以系数 0.8

备注：当这些条件中的几个同时发生时，相应的折减系数也应该连乘。 3.4.3轧制的构件和钢铸构件的物理性能指标应根据表格3.4.3

表3.4.3 轧制构件和钢铸件的物理性能指标

3.5结构或构件变形的规定

3.5.1 为了不影响适用性，不影响结构或者构件的外观，在设计时对它们的变形（挠曲或侧移）作相应的限值。按照一般的规定，结构或构件变形的限制件本规范附录A，当有工程经验或者特殊要求时，这样的限值可以在不影响正常的使用和外观要求的条件下，作适当的修改

3.5.2在钢结构或构件的变形计算中，可以不考虑螺栓孔（或铆钉孔）面积减少的影响。

3.5.3为了改善外观和使用条件，可以将横向受力构件预先起拱，起拱的大小根据实际情况而定，一般情况下是以恒载标准值加二分之一活载标准值所产生的挠度值。当仅为改善外观条件时，构件挠度应取结构在恒载和活载标准值作用下的挠度计算值减去预拱值。

4 挠曲构件的计算

4.1强度

4.1.1 在主平面内受弯构件的弯曲强度应按下式计算（考虑构件屈曲强度的参见本规范4.4.1）：

式中 Mx ，My——在同一位置处x轴和y轴的弯矩（对工字型截面，x轴为强轴，y轴为弱轴）

Wnx，Wny——对x轴和y轴的净截面模量

rx、ry ——塑性调整系数，对工字型rx = 1.05 ，ry = 1.2，对箱型rx，ry

= 1.05，对于其它的类型看表5.2.1 :f —— 钢构件弯曲强度设计值

当梁的受压翼缘的宽度与其厚度的壁纸大

于

，但小

于

MyMx

fxWnxyWny

(4.1.1)

时，rx应取1.0，fy为钢材对应等级的屈服点的强度。

对也要求抗疲劳验算的梁，rx，ry = 1.0

4.1.2 在主平面内受弯的实腹构件的抗剪强度应按下式计算。

（考虑构件屈曲强度的参见本规



范4.4.1）：

fv (4.1.2) Itw

式中：V ——在计算区域的腹板位置的剪力

I ——毛截面的惯性矩

'tw——腹板厚度

'fv——钢材的剪力强度设计值

4.1.3当在梁的上翼缘受有沿腹板平面的的集中荷载作用时，并且没有足够的支撑加劲肋时，在；腹板计算高度上的局部承压强度应按下式计算：

c

F

twlz

f

(4.1.3－1)

式中：F ——集中荷载，在动荷载作用下考虑到动力系数；

——集中荷载加强系数，对重要的吊车主梁 =1.35 ，对其它的横

梁或者主梁 =1.0

Lz ——在腹板上边缘计算高度上的集中荷载虚拟的分布长度：

Lz = a + 5hy +2

'a ——沿着梁跨度方向的集中荷载的承压长度，对于钢轨上的轮压取

50mm

'hy——自主梁或横梁顶面至腹板计算高度上边缘的距离

——钢轨的高度，对于顶上没有钢轨的梁取

'f ——钢构件的抗压强度设计值

在梁的支座处，当没有加劲肋支撑时，在它有效高度的低腹板处的局部

压力也应该用公式（4.1.3-1）

，取 =1.0。支座最终反作用力的分布长度由公式（4.1.3-2）和根据支撑尺寸决定。

注：腹板的有效高度 ho是：对于轧制主梁：为腹板与上、下翼缘相连接

处两内弧起点间的距离；对于焊接下翼缘与主梁，是腹板的高度；对铆接（或高强螺栓）连接的主梁：为上、

腹板连接的铆钉（或高强螺栓）线间的最近距离（见图4.3.2）。

4.1.4梁的腹板在计算高度边缘处，有相当大的正常正应力、剪应力和局部压应力，（或相当大的正应力和切应力）（例如在连续梁中部支座处或梁的翼缘截面改变出等）存在时，其它的折算盈利应按下式计算：

式中：, , c—在同一节点的有效的腹板计算高度边缘，同时产生的正

应力、剪应力和局部压应力。剪应力和局部压应力应分别由

公式（4.1.2）和公式

（4.1.3-1）计算。正应力按下式计算：



和以拉应力为整治，当是压应力时为负值； In ——横梁的净截面惯性矩 'y1——从计算点到梁中轴线的距离

——计算折算应力的设计值放大系数，当

和

的符号不同时，取=1.2，

4.2整体稳定

4.2.1 当出现下列之一条件时，可以不考虑梁的整体稳定计算：

1、当有稳定的平板（加固的混凝土平板或钢材平板）与受压翼缘相连接，可以约束它的侧移时。

2、当由轧制的H型钢或I字钢的受压翼缘的自由长度与受压翼缘的宽度的比例不超

过表4.2.1所给出的值时。

1f (4.1.4－

y1 (4.1.4－2) In

当和的符号相同时，或者当=0时， =1.1

表4.2.1 仅由轧制的H型钢或I字钢不需要计算受压稳定性的

受压翼缘的自由长度与宽度的最大l1/b1值

备注：在表4.2.1中除Q235钢的其它不需要计算的最大的l1/b1的比值应取Q235钢的数字乘以

对有跨内买有侧移支撑的梁，l1是跨长对跨内有侧移支撑的梁，l1是两个支撑点的距离（梁的支座处被看做有支撑）

4.2.2 除了表4.2.1中的情况外，受弯的H型钢和I字钢在主平面内的整体稳定性应按下式计算：

MyMx

fbWxyWy

(4.2.3)

式中：Wx，Wy——按受压纤维确定的对x轴和y轴的毛截面模量

4.2.4 不符合4.2.1条情况的整体箱型梁，其界面尺寸（图4.2.4）应满足h/b

符合上述规定的箱型截面简直了，可以不用计算整体稳定性。

——受弯构件的强轴的压杆稳定系数，与4.2.2条的一样

Figure 4.2.4 Box-section

4.2.5 在梁的支座处，应采取构造措施，应阻止梁端截面的扭转。

4.2.6用作减小受压翼缘自由长度的侧向支撑，其支撑应力将梁的受压翼缘视为轴心受压构件按5.1.7条款计算。

4.3局部稳定

4.3.1 承载静力荷载或间接荷载的组合梁应考虑腹板屈曲后的强度，根据规范4.4的规定计算其抗弯和抗剪的承载力；而直接承受动荷载以及类似构件或其它不考虑屈曲后强度的组合梁，则应该按规范的第4.3.2条款的规定布置加劲肋。当

规定计算腹板的稳定性。

在轻级、中级工作的吊车梁的腹板稳定性计算时，吊车梁轮压的设计值可以乘以折减系数0.9。

时，尚应按本规范第4.3.3跳空开至第4.3.5条款的

4.3.2组合梁中的腹板的加劲肋须满足以下的预防措施（图.4.3.2.):

Figure 4.3.2 Layout of stiffeners

1- transverse stiffeners; 2- longitudinal stiffeners; 3- short stiffeners

1、当ho/tw

时，对局部压应力

不等于0，为了满足设计要求应

按构造配置加劲肋，当局部压应力

2、当ho/tw>80

=0时，可以不配置加劲肋。

时（受压翼

时，应配置横向加劲肋。当ho/tw>170

缘的扭转受到约束，例如连接有刚性铺板，阻止振动的板或焊有钢轨时）或者ho/tw>150

时（受压翼缘的扭转未受限制）或者需按计算需要时，应该在弯

曲应力较大的受压区再另外配置纵向加劲肋。对于考虑局部压应力的梁，在必要的时候也应在受压区配置短的加劲肋。

无论任何条件下，ho/tw不应该超过250

综上所述的，ho时有效的腹板计算高度（对于单轴对称梁，当判断时候需要配置加劲肋时，ho应取腹板受压区高度ho的2倍），tw为腹板的厚度。

3、当在梁的支座处和在承受较大的集中固定荷载的上翼缘处，均应设置支撑加劲肋。

4.3.3对设置横向加劲肋的梁翼缘板（图.4.3.2a），其局部压应力应用下列的表达式计算：



c1 (4.3.3－1) crcrc, cr

式中： —在所计算腹板区隔内，由平均弯矩引起的在腹板计算高度边缘引起的

的的

来计算，但

部压应

力，由下列的公式计算取=1.0;

cr, cr, c, cr—由单独作用下的应力引起的临界压应力、剪切力和局平均剪应力，Vht, hw表示腹板高度；

ww

c—在腹板计算高度边缘的有效的局部压应力，用公式(4.1.3－1) 应力；

—在所计算腹板区隔内，由平均剪力引起的在腹板计算高度边缘引起

1)cr 由下列的公式计算当 b≤0.85

cr=f (4.3.3－

2a)

当 0.85

cr=[1-0.75(b-0.85)]f

(4.3.3－2b)

当 b>1.25

cr1.1f2 (4.3.3

－2c)

式中 b—在腹板受弯计算中的正常高厚比；当梁的受压翼缘受到扭转的约束时：

b

(4.3.3－2d)

当梁的受压翼缘未受到扭转的约束时：

b

(4.3.3－2e)

式中 hc—梁的腹板弯曲受压区的高度，对双轴对称的截面2hc= h0 2)cr 由下列的公式计算：当 s≤0.8

cr=fv

(4.3.3－3a)

当 0.8

cr10.5

9s0.f8 v

当 s>1.2 cr1.1f2vs (4.3.3－3c)

式中 s—用于腹板的受剪计算时通用的高后比

当 a/h0≤1.0

s

当 a/h0>1.0

s

3） c,cr由下列的公式计算：当 c≤0.9

c, cr =f 当 0.9

c,cr=[1-0.79(c-0.9)]f

(4.3.3－3b)

(4.3.3－3d)

(4.3.3－3e)

(4.3.3－4a)

(4.3.3－4b)

当 c>1.2

f2 c c,cr1.1

(4.3.3－4c)

式中 c—在局部压力作用下的翼缘的通用高厚比。

当 0.5≤a/h0≤1.5

c

(4.3.3－4d)

当 1.5

c

(4.3.3－4e)

4.3.4 既有横向加劲肋又有纵向加劲肋加强的腹板（图.4.3.2b，c），用下列的公式检测局部稳定性：

1 受压翼缘与纵向加劲肋之间的区格

c

1.0 (4.3.4－1) cr1cr1cr1

式中  cr1, cr1, c,cr1 由下列的公式计算

1） cr1 r由下列的公式（4.3.3—2）计算，但是b 改用下列的b1 代替当梁的受压翼缘扭转受到约束时：

b1(4.3.4－

2a)

当梁的受压翼缘扭转受到约束时： (4.3.4－2b)

式中 h1—纵向加劲肋至腹板计算高度受压边缘的距离

2）cr1 由下列的公式（4.3.3—3）计算，并将式中的h1代替ho，

b1

3) c,cr1 由下列的公式（4.3.3—2）计算，并将式中的c1代替b ，当梁的受压翼缘扭转受到约束时：

c1

(4.3.4－3a)

当梁的受压翼缘扭转未受到约束时：

c1

(4.3.4－3b)

2 受拉翼缘与纵向加劲肋之间的区格

(

22

)()2c21.0 (4.3.4－4) cr2cr2c,cr2

式中 2— 在所计算的区格内由平均的弯矩所产生的腹板内在纵向加劲肋处的弯曲

正应力;

c2—在纵向加劲肋处的腹板的横向正应力，取0.3c.

1）cr2 由下列的公式（4.3.3—2）计算，并用b2代替b

b2

(4.3.4－5)

2）cr2 由下列的公式（4.3.3—3）计算，并用h2代替h0 (h2= h0-h1). 3）c,cr2 由下列的公式（4.3.3—4）计算，并用h2代替h0，当 a/h2>2时取a/h2=2

附件2：外文原文（出自:钢结构设计规范 GB50017-2003）

3.4 Design indices

3.4.1 The design value of steel strength shall be taken from Table 3.4.1-1 according to the steel thickness or diameter. The design value of strength of cast steel parts shall be taken from Table 3.4.1-2. The design value of connection strength shall be taken from Tables 3.4.1-3 through 3.4.1-5.

for members subject to axial force, it is the thickness of the thicker plate element of the section.

guaranteed that the mechanical properties of the deposited metal is not lower than the requirement of the current national standards “Carbon steel electrodes and fluxes

for submerged arc welding”GB/T5293 and “ Fluxes for the submerged arc welding of low alloy steel” GB/T12470.

2. The weld quality class shall comply with the requirements of the current national

standard “Code for acceptance of construction quality of steel structures” GB 50205. For butt welds of steel components thinner than 8mm ultrasonic flaw detector shall not be used to determine the weld quality class.

3. For butt welds subject to flexion, takefcw as the design value of strength in

compression zone and ftw in tension zone.

4. “Thickness” in this table denotes the steel thickness at the location of calculation.

For members in axial tension and axial compression it is the thickness of the thicker plate element of the section.

Note ：1. Grade A bolts are used for bolts with ≤24mm and ≤10 or ≤150mm (take the

lesser value); grade B bolts are used for bolts with either d >24mm or l>10d or l >150mm (take the lesser value). d is the nominal diameter. l is the nominal length of bolt shank.

2. The precision and the surface roughness of holes of grade A, B bolts and the

tolerance and surface roughness of holes of grade C bolts shall meet the requirements of the current national standard “Code for acceptance of construction quality of steel structures” GB 50205.

Table 3.4.1-5 Design value of riveted connection strength (N/mm)

Note: 1. Holes made by the following processes belong to class I:

1) holes drilled to the design diameter on assembled members; 2) holes drilled to the design diameter separately on individual elements and members

by using drilling template;

3) holes drilled or punched to a smaller diameter on individual elements and reamed

afterwards to the design diameter on assembled member.

2. Holes punched or drilled without template to the design diameter on individual

elements belong to class II.

3.4.2 The design value of strength specified in Clause 3.4.1 shall be multiplied by a relevant reduction factor in the following situations of member and connection calculation: 1. Single angle connected by one leg

1) for checking member and connection strength as axially loaded, multiply by

0.85

2) for checking stability as an axially loaded compression member

Equal leg angles, multiply by 0.6+0.0015λ, but not larger

than 1.0

Unequal leg angles connected by short leg, multiply by 0.5+0.0025λ, but not larger than 1.0

Unequal leg angles connected by long leg, multiply by 0.7

where λ is the slenderness ratio, which shall be determined by the least radius of gyration for a single angle compression member without intermediate connection. Assume λ=20 when λ

2. Butt weld performed by welding from one side without backing plate, multiply by 0.85

3. Welded and riveted erection connections made high above the ground in unfavorable conditions, multiply by

0.9 4. Countersunk and semicountersunk riveted connection, multiply by 0.8

Note: When several of these situations occur simultaneously, the relevant reduction factors

shall be multiplied successively.

3.4.3 The indices of physical properties of rolled and cast steel shall be taken according to Table 3.4.3

Table 3.4.3 Indices of physical properties of rolled and cast steel

3.5 Provisions for deformation of structures and structural members

3.5.1 In order not to impair the serviceability, nor to affect the appearance of structures and structural members, their deformation (deflection or lateral drift) shall comply with the relevant limiting values in designing. The allowable values of deformation, as a general rule, are specified in Appendix A of this Code. The values therein may be suitably modified in consideration of practical experiences or to meet a specific demand, provided the serviceability is not impaired nor the appearance affected.

3.5.2 Reduction of sectional area by bolt (or rivet) holes may not be taken into account in the deformation calculation of steel structures and members.

3.5.3 In order to improve the appearance and the service condition, members subject to transverse forces may be given a predetermined camber, whose magnitude shall be set according to practical need and usually taken as the deflection caused by the unfactored dead load plus one half unfactored live load. In the case of solely improving the appearance, the member deflection shall be taken as that calculated from the unfactored dead and live load and minus the camber.

4 Calculation of flexural members

4.1 Strength

4.1.1 The bending strength of solid web members bent in their principal planes shall be checked as follows (for members taking account of web post-buckling strength see Clause 4.4.1 of this Code):

MyMx

f xWnxyWny

(4.1.1)

where Mx, My—bending moments about x- and y- axes at a common section (for

I-section, x-axis is the strong axis and y is the weak axis);

Wnx, Wny—net section moduli about x- and y-axis;

x, y—plasticity adaptation factors, x =1.05, y =1.20 for I-section,

x, y=1.05 for box section, see Table 5.2.1for other sections;

f —design value of bending strength of steel.

When the ratio of the free outstand of the compression flange to its thickness

is larger than

, but not exceedingx shall be taken as 1.0. fy

is the yield strength of the material indicated by the steel grade. For beams requiring fatigue checking, x=y =1.0 should be used. 4.1.2 The shear strength of solid web members bent in their principal plane shall be checked by the following formula (for members taking account of web post-buckling strength, see Clause 4.4.1 of this Code):

fv

Itw

(4.1.2)

where V—shear force in the calculated section along the plane of web;

S—static moment about neutral axis of that part of the gross section above

the location where shear stress is calculated;

I—moment of inertia of gross section; tw—web thickness;

fv—design value of shear strength of steel.

4.1.3 When a concentrated load is acting along the web plane on the upper flange of the beam, and that no bearing stiffener is provided at the loading location, the local compressive stress of the web at the upper edge of its effective depth shall be computed as follows:

F

cf (4.1.3－1)

twlzwhere F—concentrated load, taking into account the impact factor in case of

dynamic loading;

—amplification coefficient of the concentrated load, =1.35 for heavy

duty crane girder; =1.0 for other beams and girders;

lz—assumed distribution length of the concentrated load on the upper edge

of the effective web depth taken as:

lza5hy2hR (4.1.3－2) a—bearing length of the concentrated load along the beam span, taken as 50mm

for wheel loading on rail;

hy—distance from the top of girders or beams to the upper edge of the

effective web depth;

hR—depth of the rail, hR =0 for beams without rail on top; f—design value of compressive strength of steel. At the beam support, when no bearing stiffener is provided, the local compressive stress in the web at its lower edge of effective depth shall also be checked by Formula (4.1.3－1), with  take as 1.0. The distribution length of the end reaction shall be determined with reference to Formula(4.1.3－2) and according to the dimensions of the support.

Note: The effective web depth h0 is:

For rolled beams: the distance between the web toes of the fillets joining

the web with the upper and lower flanges;

For welded girders: the depth of the web;

For riveted（or high-strength bolted）girders: the distance between the

nearest gauge lines of rivets (or high-strength bolts) connecting the web with the upper and lower flanges (see Fig. 4.3.2).

4.1.4 In case comparatively large normal stress , shear stress , and local compressive stress c(or comparatively large and) exist simultaneously at the edge of the effective web depth of build–up girders, e. g. at the intermediate support of a continuous girder or at a section where the flange changes its dimensions, the reduced stress shall be checked by the following expression

1f (4.1.4－1)

where , , c—normal stress, shear stress and local compressive stress occurring

simultaneously at a same point on the edge of effective web depth.  and c are calculated by Formulae (4.1.2) and (4.1.3－1) respectively, while  is determined as follows:

My1 (4.1.4－2)

 and c are taken as positive while being tensile and negative while

compressive;

In—moment of inertia of the net beam section;

y1—distance from the calculated point to the neutral axis of the beam

section;

1—amplification coefficient of design value of strength for reduced

stress, 1=1.2 when  and c are of different signs, 1=1.1 when  and c are of the same sign or when c =0.

4.2 Overall stability

4.2.1 Calculation of the overall stability of the beams may not be needed when

one of the following situations takes place:

1. A rigid decking (reinforced concrete slab or steel plate) is securely connected to the compression flange of the beam and capable of preventing its lateral deflection;

2. The ratio of the unsupported length, l1, of the compression flange of a simply supported rolled H- or uniform I-section beam to its flange width, b1, does not exceed the values given in Table 4.2.1.

Table 4.2.1 Maximum l1/b1 values of simply supported

rolled H- or uniform I-section beams to avoid

checking for overall stability

Note: The maximum 1/1values of beams made of steel grade other than those shown For beams devoid of lateral support within the span, l1 is the span length;

for those provided with lateral supports within the span, l1 is the distance between these supports (beam bearings are considered as supports).

4.2.2 Except for the situations specified in Clause 4.2.1, members bent in their principal plane of largest rigidity shall be checked for overall stability as follows:

f (4.2.2) bWx

where Mx—maximum bending moment about the strong axis;

Wx—gross section modulus of the beam with respect to compression fibers; b—overall stability factor determined according to Appendix B.

4.2.3 Except for the situations specified in Clause 4.2.1, H- and I-section members bent in their two principal planes shall be checked for overall stability as follows:

MyMx

f (4.2.3) bWxyWy

where Wx, Wy—gross section moduli about x- and y- axes with respect to compression

fibers;

b—overall stability factor for members bent about the strong axis, same as in Clause 4.2.2.

4.2.4 Simply supported box section beams not conforming to the first situation

specified in Clause 4.2.1 shall have their cross section dimension (Fig. 4.2.4) meeting the relationships h/b0≤6 and l1/b095(235/fy).

Simply supported box section beams fulfilling the above requirement may not be checked for overall stability.

Figure 4.2.4 Box-section

4.2.5 Detailing measures shall be taken to prevent twisting of the section at beam end supports.

4.2.6 Lateral bracings for reducing the unsupported length of the compression flange of a beam shall have their axial force determined in accordance to Clause 5.1.7 by considering the compression flange as an axially loaded compression member.

4.3 Local stability

4.3.1 Built-up girders subject to static or indirect dynamic loading should take account of web post-buckling strength with their bending and shear capacities checked in accordance with sub-chapter 4.4; crane girders and similar members subject to direct dynamic loading, or other girders not taking account of post-buckling strength, shall be provided with stiffeners in accordance with Clause

4.3.2. In case h0/twrequirements of clauses 4.3.3 through 4.3.5.

In checking the web stability of light and medium duty crane girders, the design value of crane wheel load may be multiplied by a reduction factor 0.9.

4.3.2 Stiffeners shall be provided for webs of built-up girders in accordance with the following provisions (Fig.4.3.2):

1. When h0/t

w≤transverse stiffeners shall be provided for girders with local compressive stress(c≠0) in accordance with detailing requirements, but may not be provided for girders without local compressive stress(c

=0).

Transverse stiffeners shall be provided in case h0/twwhich,

when h0/twof compression flange is restrained, such as connected with rigid slab, surge plate or welded-on rail)

or h0/twcalculation, longitudinal stiffeners shall be added in the compression zone of large flexural stress panels. For girders with considerable local compressive stress, additional short stiffeners should also be provided if necessary.

h0/tw shall in no case exceed 250.

In the above, h0 is the effective web depth (for monosymmetric girders, h0 shall be taken as twice the height of compression zone hc in judging whether longitudinal stiffeners are necessary), tw is the web thickness.

Figure 4.3.2 Layout of stiffeners

1- transverse stiffeners; 2- longitudinal stiffeners; 3- short

stiffeners 3. Bearing stiffeners shall be provided at girder supports and anywhere a fixed and comparatively large concentrated load is applied on the upper flange. 4.3.3 Panels of girder webs provided solely with transverse stiffeners (Fig.4.3.2a) shall be checked for local stability by the following expression

c

1 (4.3.3－1) 

c, crcrcr

where —bending compressive stress at the edge of effective depth of the web

caused by the average bending moment in the calculated web panel;

—mean shear stress of the web caused by the average shear force in the

calculated web panel, V

hwtw

, hw being the web depth.

c—local compressive stress at the edge of effective depth of the web,

calculated with formula (4.1.3－1), but taking =1.0;

cr, cr, c, cr—critical value of bending-, shear- and local compressive stress,

acting individually and calculated as follows:

1) cr is calculated with the following formulae When b≤0.85

cr=f (4.3.3－2a)

When 0.85

cr=[1-0.75(b-0.85)]f (4.3.3－2b) When b>1.25

cr1.1f2 (4.3.3－2c)

where b— normalized depth-thickness ratio for calculation of web subject to flexion;

When twisting of the girder compression flange is restrained:

b

－2d)

When twisting of the girder compression flange is not restrained:

b

－2e)

where hc—the height of bending compression zone of girder web, 2hc= h0 for doubly symmetric section.

2) cr is calculated with the following formulae When s≤0.8

cr=fv (4.3.3

－3a)

When 0.8

cr10.59s0.8fv (4.3.

3－3b)

When s>1.2

cr1.1fvs2 (4.3.3－3

where s—normalized depth-thickness ratio for calculation of webs subject to shear.

When a/h0≤1.0

s

(4.3.3－3d)

When a/h0>1.0

s

(4.3.3－3e)

3) c,cr is calculated with the following formulae When c≤0.9

c, cr =f (4.3.3－4a) When 0.9

c,cr=[1-0.79(c-0.9)]f (4.3.3－

4b)

When c>1.2

c,cr1.1fc2 (4.3.3－4c)

where c—normalized depth-thickness ratio for webs under localized compression. When 0.5≤a/h0≤1.5

c

－4d)

When 1.5

2.0

c－4e)

4.3.4 Webs strengthened simultaneously with transverse and longitudinal

stiffeners (Fig.4.3.2b, c) shall be checked for local stability by the following expressions:

1 Panels between compression flange and longitudinal stiffener

c1.0 (4.3.4－1) cr1cr1cr1

where  cr1, cr1, c,cr1 are calculated as follows

1)  cr1 is calculated with formulae (4.3.3-2), but b

thereof is replaced by b1.

When twisting of the girder compression flange is restrained

b1

－2a)

When twisting of the girder compression flange is not restrained

b1

－2b)

where h1—distance from the longitudinal stiffener to the compressive edge of the

effective web depth.

2) cr1 is given by formulae (4.3.3－3), but replacing h0 thereof by h1. 3) c,cr1 is given by formulae (4.3.3－2), but replacing b thereof byc1.

When twisting of the girder compression flange is restrained

c1

－3a)

When twisting of the girder compression flange is not restrained

c1

－3b)

2 Panels between tension flange and the longitudinal stiffeners



(2)2()2c21.0 (4.3.4－4) cr2cr2c,cr2where 2—web bending compressive stress at the location of the longitudinal

stiffener caused by the average bending moment in the calculated panel; c2—transverse compressive stress of the web at the location of longitudinal stiffener, taken as 0.3c.

1) cr2 is given by formulae (4.3.3-2), but replacing b thereof by b2

b2

(4.3.4－5)

2) cr2 is given by formulae(4.3.3－3), but replacing h0 thereof by h2(h2= h0-h1). 3) c,cr2 is given by formulae(4.3.3－4), but replacing h0 thereof by h2, take

a/h2=2 when a/h2>2.

注明原文出处