Section 507.docx

SECTION 507 - PLATE GIRDERS

stress given in Section 506, M

507.1 SCOPE 507.1.1 Plate girders shall be distinguished from beams on the basis of the web slenderness ratio

R PG=1−0 . 0005

h/t w . When this value is greater than

2547/ √ Fy

, the provisions of this Sections shall apply for allowable bending stress, otherwise Section 506 is applicable.

507.2 WEB SLENDERNESS LIMITATIONS

under

507.2.2 When transverse stiffeners are provided, spaced not more than 1½ times the distance between flanges: h 5,250 ∠ t w √ Fy ∫¿ ¿

investigation,

Af =

mm

2

area of compression flange,

2

α=0.6F yw / Fb ∠1.0 507.4 ALLOWABLE SHEAR STRESS WITH TENSION FIELD ACTION 507.4.1 Except as herein provided, the largest

f

(507-2)

507.3 ALLOWABLE BENDING STRESS 507.3.1 When the web depth-to-thickness ratio

√

exceeds 2547/ Fy , maximum bending stress in the compression flange shall not exceed:

F ' h ∠F b R PG R e

Re =1.0 )

A w = area of web at the section

mm (507-1)

)

Aw ( 3 α−α3 ) Af Re = ∠1. 0 Aw 12+2 Af (non-hybrid girders,

h 96 , 530 ∠ t w √ Fy ( Fy+114 )

(

12+

507.1.2 For allowable shear stress and transverse stiffener design see appropriate Articles in Section in Section 506 or this Section if tension field action is utilized.

507.2.1 When no transverse stiffeners are provided, spaced not more than 1½ times the distance between the flanges:

Aw h 1996 − ∠1 . 0 A f t √ Fb

(507-3)

where:

Fb = applicable bending

average web shear, v , in MPa, computed for any condition of complete or partial loading, shall not exceed the value given by Equation (506-16). 507-4.2 Alternatively, for girders other than hybrid girders, if intermediate stiffeners are provided and spaced to satisfy the provisions of

C ∠1

v Section 507.5 and if , the allowable shear including tension field action given by Equation (507-4) is permitted in lieu of the value given by Equation (506-16).

F 1−C v F v= y C v + 2 2 .89 1 .15 √ 1+ ( a /h )

(

C v ,a , h, and t are as defined in

)

Section 506.5. (507-

Y=

4)

ratio of yield stress of web steel

to

507.5 TRANSVERSE STIFFENERS

yield stress of stiffener steel

D=

507.5.1 Transverse stiffeners shall meet the requirements of Section 506.6.

1.0 for stiffeners furnished in

pairs =

507.5.2 In girders designed on the basis of tension field action, the spacing between stiffeners at end panels, at panels containing large holes, and at panels adjacent to panels

f

containing large holes shall be such that v does not exceed the value given by Equation (506-16). 507.5.3 Bolts and rivets connecting stiffeners to the girder web shall be spaced not more than 300 mm. on centers. If intermittent fillet welds shall not be more than 16 times the web thickness nor more than 250 mm.

=

f

507.5.6 When the greatest shear stress v in a panel is less than that permitted by Equation (507-4), the reduction of this gross are requirements permitted in like proportion. 507.5.7 Intermediate stiffeners are required by Equation (507-4) shall be connected for a total shear transfer, in N per linear millimeter of single stiffener or pair of stiffeners, not less than:

√(

Fy f vs=h 5990

I

507.5.4 The moment of inertia, sl , of a pair of intermediate stiffeners, or a single intermediate stiffener, with reference to an axis in the plane of the web, shall be limited as follows:

h I sl ≥ 50

( )

(507-5) 2

stiffeners are furnished in pair), in mm , of intermediate stiffeners spaced as required for Equation (507-4) shall not be less than:

1−C v a ( a /h )2 A st = − YDht 2 h √1+ ( a /h )2 (507-6) where:

3

)

(507-7)

where:

Fy=

yield stress of web steel, MPa

507.5.8 This shear transfer may be reduced in the same proportion that the largest computed

4

507.5.5 The gross area (total area, when

(

1.8 for single angle stiffener 2.4 for single plate stiffeners

)

f

shear stress v in the adjacent panels is less than that permitted by Equation (507-4). However, rivets and welds in intermediate stiffeners which are required to transmit to the web an applied concentrated load or reaction shall be proportioned for not less than the applied load or reaction. 507.5.9 Intermediate stiffeners may be stopped short of the tension flange, provided bearing is not needed to transmit a concentrated load or reaction. The weld by which intermediate stiffeners are attached to the web shall be

terminated not closer than 4 times nor more than 6 times the web thickness from the near toe of the web-to-flange weld. When single stiffeners are used, they shall be attached to the compression flange, if it consists of rectangular plate, it resist any uplift tendency due to torsion in the plate. When a lateral bracing is attached to a stiffener, or a pair of stiffeners, in turn, these shall be connected to a compression flange to transmit 1% of the total flange stiffener unless the flange is composed only of angles.

507.6 COMBINED SHEAR ANND TENSION STRESS 507.6.1 Plate girder webs which depend upon tension field action, as provided in Equation (507-4), shall be so proportioned that bending tensile stress, due to moment in the plane of the

0.60 Fy

girder web, shall not exceed

(

0 . 825−0 . 375

fv Fy Fv

)

nor

(507-8)

where:

f v= computed average web shear stress (total shear divided by web area), MPa

F v= allowable web shear stress according to Equation (507-4), MPa 507.6.2 The allowable shear stress in the webs of girders having flanges and webs with yield point greater than 448 MPa shall not exceed the values given by Equation (506-16) if the flexural stress in the flange

f b exceeds 0.75 F b .