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CONNECTIONS

3.20 CHAPTER THREE

TABLE 3.5 Traditional Allowable Loads on Threaded Welded Studs*
Stud size, in Tension, kips Single shear, kips
5 6.9 4.1
/ 8
3 10.0 6.0
/ 4
7 13.9 8.3
/ 8
1 18.2 10.9
*ASTM 108, Grade 1015, 1018, or 1020.

to achieve the Class C surface, the faying surfaces must be roughened by hand wire brushing. Power
wire brushing should not be used, since it tends to polish rather than roughen the faying surfaces,
thereby decreasing the slip resistance. Without the final step of hand wire brushing, the slip resistance
is less than half that of a properly prepared Class C surface. Test results (Kulak et al., 1987) and field
experience have shown that hot-dip galvanized slip-critical connections may experience creep over
time. Thus it is advisable to use only standard holes for hot-dipped galvanized steel.

3.2.9 Specifying Bolts
When working with competent fabricators and detailers, engineers should avoid specifying bolts too
tightly. The connection design engineer should be given the latitude to choose bolt grades, diame-
ters, hole types, and connection types, within the limits allowed by AISC and RCSC, to achieve max-
imum efficiency and economy in both the shop and the field. Slip-critical connections should only
be required where specified by AISC and RCSC, unless unusual circumstances exist where slip can-
not be tolerated. Slip-critical connections should not be specified to obtain an added factor of safety,
since in many cases additional bolts will not translate into additional reliability, but will result in
added cost.
To prevent mistakes in the field, it is good practice to avoid choosing bolts with the same diam-
eter but different grades. Therefore, if both A490 and A325 bolts are to be furnished, they should be
7
of different diameters, such as 1-in-diameter A490 bolts and / 8-in-diameter A325 bolts. Since the
oversized hole diameter of a bolt is often the same as the standard hole diameter of the next larger
bolt, some engineers also prefer to skip a size to prevent field mistakes. Therefore, they would fur-
7
1
7
3
nish / 4-in- and 1-in-diameter bolts, or / 8-in- and 1 / 8-in-diameter bolts, instead of / 8-in- and 1-in-
diameter bolts.
3.2.10 Welded Studs
Studs, fasteners with one end welded to a steel member, frequently are used for connecting material.
Shear connectors in composite construction are a common application. Welded studs also are used as
anchors to attach wood, masonry, or concrete to steel. Threaded studs can also be used for steel-to-steel
connections to cut costs. For example, fastening rail clips to crane girders with studs eliminates drilling
of the top flange of the girders and may permit a reduction in flange size.
Types of studs and welding guns vary with manufacturers.
Table 3.5 lists traditional allowable loads (safety factor includ-
ed) for several sizes of threaded studs. Check manufacturer data
for studs to be used. Chemical composition and physical prop-
erties may differ from those assumed for this table.
In designs with threaded studs, clearance must be provid-
ed for stud welds. Usual sizes of these welds are indicated in
Fig. 3.12 and Table 3.6. The dimension C given is the mini-
mum required to prevent burn-through in stud welding.
FIGURE 3.12 Welded stud. Other design considerations may require greater thicknesses.

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