Civil Engineering Reference
In-Depth Information
TABLE 7.2
Allowable Weld Stresses
Weld Type
Allowable Shear Stress (ksi)
CJP or PJP
0.35 F y
Fillet (60 ksi electrode)
16.5 but < 0.35 F y on base metal
Fillet (70 ksi electrode)
19.0 but < 0.35 F y on base metal
Fillet (80 ksi electrode)
22.0 but < 0.35 F y on base metal
7.2.6.1.4.2 Bottom Flange-to-Web Connection (Simply Supported Girder
Spans) The horizontal shear flow for which the bottom (tension) flange weld is to
be designed is
q f = Δ
VQ f
I
Δ
,
(7.69)
Δ
¯
where
y isthedistancefromthe
bottom flange-to-web connection to the neutral axis, and Q f =
V istheshearforcerangefromliveloadplusimpact,
A f (d f −¯
y) (statical
moment of the bottom flange area about the neutral axis). The required effective
area of weld can then be established based on the allowable weld fatigue shear stress
(typically Category B or B depending on weld backing bar usage) for the range of
live load shear flow.
7.2.6.1.5 Girder Bearing Stiffeners
Concentratedloads(e.g.,reactionsattheendsofgirders)createlocalizedconcentrated
compressive stresses that may exceed yield stress. The localized yielding or web
crippling may be resisted by web plates of sufficient thickness or by pairs of stiffeners.
Web crippling can be conservatively analyzed as shown in Figure 7.15. The minimum
P
1:1
L B
0.75 F y
F y
k
Toe of fillet
R
L B
FIGURE 7.15 Web crippling (stress distribution at the toe of the fillet shown).
 
 
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