J10. ANCHOR RODS AND EMBEDMENTS

J10. ANCHOR RODS AND EMBEDMENTS

Steel anchor rods and embedments shall be proportioned to develop the factored load combinations stipulated in Section A4. If the load factors and combinations

16.1–90 LOCAL BUCKLING [App. B5.

3a. Unstiffened Compression Elements

The design strength of unstiffened compression elements whose width-thickness ratio exceeds the applicable limit l r as stipulated in Section B5.1 shall be subject to

a reduction factor Q s . The value of Q s shall be determined by Equations A-B5-3 through A-B5-10, as applicable. When such elements comprise the compression flange of a flexural member, the design flexural strength, in ksi, shall be computed

using f b F y Q s , where f b = 0.90. The design strength of axially loaded compression members shall be modified by the appropriate reduction factor Q, as provided in Appendix B5.3d.

(a) For single angles:

when 0.45 EF / y < bt / < 0.91 EF / y :

Q s = 1.340 - 0.76( / ) bt F y / E (A-B5-3)

Rev. 9/4/01

when bt / > 0.91 EF / y :

E 0.53 / é Fbt

ë y () / ù û

(A-B5-4)

(b) For flanges, angles, and plates projecting from rolled beams or columns or other compression members:

when 0.56 EF / y < bt / < 1.03 EF / y :

Q s = 1.415 0.74( / ) - bt F y / E (A-B5-5)

when bt / ³ 1.03 EF / y :

E 0.69 / é Fbt y () / ù

(A-B5-6) (c) For flanges, angles and plates projecting from built-up columns or other com-

pression members:

when 0.64 EF /( y / k c ) < bt / < 1.17 EF /( y / k c ):

Q s = 1.415 0.65( / ) ( - bt F y / kE c )

(A-B5-7)

when bt / ³ 1.17 EF /( y / k c ): Q 2

s = 0.90 Ek c / é Fbt / ù ë y () û

(A-B5-8)

App. B5.]

LOCAL BUCKLING

, 0 35 . £ k c £ . 0 763

ht / w where

h = depth of web, in. (mm) t w = thickness of web, in. (mm)

(b) For other sections: k c = 0.763 (d) For stems of tees:

when 0.75 EF / y < dt / < 1.03 EF / y :

Q s = 1.908 1.22( / ) - dt F y / E (A-B5-9)

when dt / ³ 1.03 EF /

Rev.

(A-B5-10) where

E 0.69 / é ë F y (/) dt ù

û Rev.

d = width of unstiffened compression element as defined in Section B5.1, in. (mm) t = thickness of unstiffened element, in. (mm)

3b. Stiffened Compression Elements

When the width-thickness ratio of uniformly compressed stiffened elements (except perforated cover plates) exceeds the limit l r stipulated in Section B5.1, a

reduced effective width b e shall be used in computing the design properties of the section containing the element.

(a) For flanges of square and rectangular sections of uniform thickness:

when ³ 1.40 :

0.38 E ù

b e = 1.91 t

f ê ê ë (/) bt f ú û ú

(A-B5-11)

otherwise b e = b. (b) For other uniformly compressed elements:

when b ³ E 1.49 :

0.34 E ù

b e = 1.91 t

ê 1 f - (/) bt f ú

(A-B5-12)

16.1–98 DESIGN FOR FLEXURE [App. F1.

TABLE A-F1.1 Nominal Strength Parameters

Plastic Moment

Limiting Buckling Shape

Limit State of

Buckling

Moment M r

Channels and doubly

F L S x and singly symmetric

LTB doubly symmetric

[b]

members and channels

I -shaped beams (includ- ing hybrid beams) bent

LTB singly symmetric

about major axis [a]

F y S y and singly symmetric I -shaped members bent about minor axis [a]

Channels and doubly

FLB

NOTE: LTB applies only for strong axis bending. [a] Excluding double angles and tees. [b] Computed from fully plastic stress distribution for hybrid sections.

Rev. p EGJA

9/4/01 [c] X 1 = S

[e] F = M cr , where M

2 EC b 2

b 2 1 ) û ú ù£ p

IJB y é ê + L + ë 1 ( 1 B + B M

B= 1 ë é (I 2.25 2 yc y /I )– 1 ù û (h/L ) (I /J) b y

2 yc y

B= 25(1 – I /I )(I

yc /J)(h/L ) b

I yc y 1.0 if /I < 0.1or I yc y /I > 0.9

App. F3.]

WEB-TAPERED MEMBERS

5.9 E

2 (A-F3-7)

h s = factor equal to 1 0 . + . 0 023 g Ld o / A f 11/1/01

h w = factor equal to 1 0 . + . 0 00385 gLr / To r To = radius of gyration of a section at the smaller end, considering only the compression flange plus one-third of the compression web area, taken about an axis in the plane of the web, in. (mm)

A f = area of the compression flange, in. 2 (mm 2 )

and where B is determined as follows: (a) When the maximum moment M 2 in three adjacent segments of approximately

equal unbraced length is located within the central segment and M 1 is the larger moment at one end of the three-segment portion of a member:

M 2 ÷ ø (b) When the largest computed bending stress f b2 occurs at the larger end of two

+ 0.50 g 1.0 +

³ 1.0 (A-F3-8)

adjacent segments of approximately equal unbraced lengths and f b1 is the com- puted bending stress at the smaller end of the two-segment portion of a mem- ber:

B 1.0 0.58 1.0

÷ - 0.70 ç

f b 2 ÷ ø (c) When the largest computed bending stress f b 2 occurs at the smaller end of two

g 1.0 b 1

³ 1.0 (A-F3-9)

adjacent segments of approximately equal unbraced length and f b 1 is the com- puted bending stress at the larger end of the two-segment portion of a member:

1 ö 2.20 1.0 b 1 ö =

B 1.0 0.55 1.0

f b 2 ø ÷ In the foregoing, g = (d L -d o )/ d o is calculated for the unbraced length that contains

³ 1.0 (A-F3-10)

the maximum computed bending stress. M 1 /M 2 is considered as negative when producing single curvature. In the rare case where M 1 /M 2 is positive, it is recom- mended that it be taken as zero. f b1 /f b2 is considered as negative when producing single curvature. If a point of contraflexure occurs in one of two adjacent unbraced

DESIGN SHEAR STRENGTH

[App. G3.

V n = 0.6 FA yw w ç C v v +

(A-G3-2)

1.15 1 ( / ) + ah ø

Also see Appendix G4 and G5. Tension field action is not permitted for end-panels in non-hybrid plate girders, all

panels in hybrid and web-tapered plate girders, and when a / h exceeds 3.0 or [260 / 2

Rev.

(h / t w ) ] . For these cases, the nominal strength is:

V n = 0.6 FAC yw w v

(A-G3-3)

The web plate buckling coefficient k v is given as

k v =+ 5 2 (A-G3-4)

(/) ah

except that k v shall be taken as 5.0 if a / h exceeds 3.0 or [260 / (h / t w 2 )] . The shear coefficient C v is determined as follows:

kE

(a) For 1.10 v

1.10 kEF v / yw

(A-G3-5)

1.51 kE v

2 (A-G3-6)

(/ ht w ) F yw