BOLTED CONSTRUCTION
8 - 27
Table 8-15. Design Tensile Strength of Bolts, kips Nominal Bolt Diameter d, in. 5⁄ 8
3⁄ 4
7⁄ 8
1
11⁄8
11⁄4
13⁄8
11⁄2
1.227
1.485
1.767
2
Nominal Bolt Area, in.
ASTM Desig.
φFt, ksi
A325
67.5
A490 A307
84.8 33.8
0.3068
0.4418
0.6013
20.7
29.8
40.6
41.4
59.6
81.2
26.0
37.4
52.0
74.9
51.0 102
0.7854 53.0 106 66.6 133
0.9940 67.1
82.8
134
166
84.2 169
100
119
200
239
104
126
150
208
252
300
10.4
14.9
20.3
26.5
33.5
41.4
20.7
29.8
40.6
53.0
67.1
82.8
50.1 100
59.6 119
and φ = 1.0 for standard holes, oversized holes, short-slotted holes, and long-slotted holes perpendicular to the direction of the load; φ = 0.85 for long-slotted holes parallel to the direction of the load. In the above equation, n is the number of bolts in the connection. In general, slip is likely to occur at 1.4 to 1.5 times the service loads. Note that the values of Fv tabulated in LRFD Specification Table J3.6 for bolts in slip-critical connections assume Class A surfaces with µ = 0.33. As stated in LRFD Specification Section J3.8a, it is permissible to increase Fv to the applicable value in the RCSC Specification for other surfaces. When subjected to combined shear and tension, the slip capacity for comparison with service loads must be reduced by the factor: T 1 − Tb as specified in LRFD Specification Section J3.9a, where T is the unfactored force on the connection and Tb is the minimum bolt tension from LRFD Specification Table J3.1. From LRFD Specification Appendix J3.8a, the design slip resistance for comparison with factored loads is φRstr, Effective thickness in bearing db 2
db 4
Ru Ru db
Fig. 8-6. Effective thickness for bearing of countersunk bolts. AMERICAN INSTITUTE OF STEEL CONSTRUCTION