Civil Engineering Reference
In-Depth Information
Weld line properties for any weld configuration may be determined as shown in
Example 9.1.
Table 9.1
provides weld line properties for various commonly used
weld configurations.
9.2.4.4
Direct Axial Loads on Welded Connections
Axial weld connections should have at least the strength of the members being
connected and be designed to avoid large eccentricities.
Groove welds are often used for butt welds between axial tension or compres-
sion members (Figure 9.4g). Eccentricities are avoided and, with electrodes properly
chosen to match the base metal (see AWS, 2005), CJP groove welds are designed in
accordance with the base metal strength and thickness.
Fillet welds are designed to resist shear stress on the effective area,
A
e
. The size
of fillets welds is often governed by the thickness of the elements being joined and it
is necessary to determine the length of fillet weld to transmit the axial force without
eccentricity at the connection. Example 9.2 outlines the design of an axially loaded
full strength fillet weld connection that eliminates eccentricities.
Example 9.2
Design the welded connection for some secondary wind bracing shown in
50 ksi) and E70XX electrodes are used
for the SMAW fillet weld.
Considering an estimated shear lag coefficient of 0.90 (see Chapter 6), the
member strength is
T
=
0.55
(
50
)(
5.75
)
=
158.1 kips
or
T
=
(
0.90
)
0.47
(
70
)(
5.75
)
=
170.3 kips.
The minimum fillet weld size is 1/4 in. and maximum fillet weld size is
7/16 in. Try a 5/16 in. fillet weld.
t
e
=
(
5
/
16
)(
0.707
)
=
0.22 in.
From Equation 9.2, the allowable strength of the weld line is
F
w
=
t
e
(f
all
)
=
0.22
(
19
)
=
4.18 kips/in.
F
L1
L
6 × 6 × 1/2
T
F
E
3"
1.73"
A
= 5.75 in.
2
F
L2
FIGURE E9.2
