NDS Table SDPWS Table 4.2A

This sheet calculates the ASD or LRFD shear capacities for unblocked diaphrams per NDS/SDPWS Table 4-2A

1. Nominal unit shear capacities shall be adjusted in accordance with 4.2.3 to determine ASD allowable unit shear capacity and LRFD factored unit resistance. For general construction requirements see 4.2.6. For specific requirements, see 4.2.7.1 for wood structural panel diaphragms.

2. For framing grades other than Douglas Fir-Larch or Southern Pine, reduced nominal unit shear capacities shall be determined by multiplying the tabulated nominal unit shear capacity by the Specific Gravity Adjustment Factor= [1-(0.5 - G)], where G = Specific Gravity of the framing lumber from the NDS. The Specific Gravity Adjustment Factor shall not be greater than 1.

3. Apparent shear stiffness values, G.. are based on nail slip in framing with moisture content less than or equal to 19% at time of fabrication and panel stiffness values for diaphragms constructed with OSB panels. When plywood panels are used, G. values shall be determined in accordance with Appendix A.

4. Where moisture content of the framing is greater than 19% at time of fabrication, G. values shall be multiplied by 0.5.

ASD LRFD Wood Design