Design Of Wood Structures 3l1mw

,

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, Bolts, Lag Bolts, and Other Connectors

13.39

The time effect factor for LRFD load combinations in which seismic load is dominant is 1.0. The resistance factor is z 0.65 for all fasteners in the NDS. The other adjustment factors are identical for both LRFD and ASD. Adjusted LRFD capacity for the six bolt connection based on yield limit equations: Adj. Pn N(Zn) N(Zn) (z CMCtCgC) 6(18,990)(0.65)(1.0)(1.0)(1.0)(0.993)(1.0) 73,500 lb Adjusted LRFD capacity based on tension and shear stresses in the glulam member: Since net section tension, row tear-out, and group tear-out are based on failure in the wood member, the format conversion factor KF and the resistance factor are based on member design. See Sec. 4.24. For member failure in tension, the format conversion factor is KF 2.7 and the resistance factor is t 0.8. For member failure in shear, the format conversion factor is KF 2.88 and the resistance factor is v 0.75. The nominal and adjusted LRFD design values for tension and shear are: Ftn Ft (KF) 1100(2.7) 2970 psi F rtn 5 Ftn sftlCMCtd 5 2970s0.8ds1.0ds1.0ds1.0d 5 2376 psi Fvn Fv (KF) 191(2.88) 550 psi F vr n 5 Fvn sfvlCMCtd 5 550s0.75ds1.0ds1.0ds1.0d 5 412 psi Net section tension for LRFD (NDS Eq. E.2-1): Z rn NT 5 F trn sAnd 5 2376s50.6d 5 120,200 lb . 73,500 lb Row tear-out for LRFD (NDS Eqs. E.3-2 and E.3-3): Z nr RT21 5 Z nr RT22 5 nF rvn tscrit 5 3s412ds5.125ds4.0d 5 25,350 lb Z rnRT 5

nrow

Z nr RT

i51

i

5 25,350 1 25,350 5 50,700 lb , 73,500 lb

Group tear-out for LRFD (NDS Eq. E.4-1): Z nr GT 5 Z nGT r 5

Z nr RT21 Zr 1 nRT22 1 F trn Agroup2net 2 2 25,350 25,350 1 1 2376s9.93d 5 48,900 lb , 73,500 lb 2 2

The adjusted LRFD capacity is 48,900 lb due to group tear-out at the connection. The group tear-out capacity Z nr GT at the connection is approximately 67 percent of the capacity based on yield limit equations for the bolts (same as for ASD).