Page 273 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch05.qxd 9/29/05 5:12 PM Page 5.53

CRITERIA FOR BUILDING DESIGN

CRITERIA FOR BUILDING DESIGN 5.53

5.9.10 Design of Fillers
Plates used to build up the thickness of one component being spliced to another are known as fillers.
The AISC Specification gives the applicable design requirements as follows.

1
In welded construction, any filler / 4-in (6 mm) or more in thickness shall extend beyond the edges of the
splice plate and shall be welded to the part on which it is fitted with sufficient weld to transmit the splice
plate load, applied at the surface of the filler. The welds joining the splice plate to the filler shall be suf-
ficient to transmit the splice plate load and shall be long enough to avoid overloading the filler along the
1
toe of the weld. Any filler less than / 4-in (6 mm) thick shall have its edges made flush with the edges of
the splice plate and the weld size shall be the sum of the size necessary to carry the splice plus the thick-
ness of the filler plate.
1
When a bolt that carries load passes through fillers that are equal to or less than / 4-in (6 mm) thick,
the shear strength shall be used without reduction. When a bolt that carries load passes through fillers that
1
are greater than / 4-in (6 mm) thick, one of the following requirements shall apply:
3
(1) For fillers that are equal to or less than / 4-in (19 mm) thick, the shear strength of the bolts shall be
multiplied by the factor [1 − 0.4(t − 0.25)] [S.I.: [1 − 0.0154(t − 6)]], where t is the total thickness of the
3
fillers up to / 4-in (19 mm);
(2) The fillers shall be extended beyond the joint and the filler extension shall be secured with enough
bolts to uniformly distribute the total force in the connected element over the combined cross-section of
the connected element and the fillers;
(3) The size of the joint shall be increased to accommodate a number of bolts that is equivalent to the
total number required in (2) above; or
(4) The joints shall be designed to prevent slip at required member strength levels in accordance with
Sec. J3.8. [See Art. 5.9.8.]
5.9.11 Design of Splices
Groove-welded splices in plate girders and beams should develop the nominal strength of the smaller
section spliced. Other types of splices in cross sections of plate girders and beams, such as bolted
splices, should develop the strength required by the forces at the splice point.

5.9.12 Design of Components in Bearing
The available bearing strength (design bearing strength φR n and allowable bearing strength R n /Ω) for
surfaces in contact is determined for the limit state of bearing (local compressive yielding) as given
in the following. Use φ= 0.75 (LRFD) and Ω= 2.00 (ASD) for all cases.
The nominal bearing strength for milled surfaces, pins in reamed, drilled, or bored holes, and
ends of fitted bearing stiffeners, is

(5.157)
R n = 1.8F y A pb
where F y = specified minimum yield stress, ksi (MPa)
2
2
A pb = projected bearing area, in (mm )
The nominal bearing strength for expansion rollers and rockers depends on the diameter d:
If d ≤ 25 in (635 mm),
12.( F −13) ld
R = y (5.158a)
n
20
12.( F − 90) ld
SI: R = y (5.158b)
n
20

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