Dead Load Resisting Failure Combinations (0.9D)

Sizer includes a full set of load combinations for dead-load resisting failure, according to

NBC 4.1.3.2.(4),
NBC Structural Commentaries A19, A20, and A23,
CSA O86-14 Section 5.2.4.1 and Table 5.2.4.1

These are load combinations that have a 0.9D load factor instead of 1.25D, which will govern when the dead load counteracts other types of loads applied to the opposite side of the member. Examples are:

dead gravity loads counteracting wind uplift loads on beams and columns,
lateral effects of the eccentric dead loads on columns and walls counteracting wind or hydrostatic lateral loads
dead gravity loads counteracting mechanically induced uplift from patterned snow or live loads

The table below gives the counteracting load combinations that are generated using the load types D, L, S and W. The comments below the table explain how to extend this to the load types Ds, Lf/s, H and E.

Load Type	Combination	Case
D	None	1
D,L	0.9D + 1.5L	2
D,S	0.9D + 1.5S	3
D,W	0.9D + 1.4W	4
D,L,W	0.9D + 1.5L + 0.4W 0.9D + 1.4W + 0.5L plus D,L and D,W	2 4
D,L,S¹	0.9D + 1.5L + 1.0S¹ 0.9D + 1.5S + 1.0L¹ plus D,L and D,S	2 3
D,S,W	0.9D + 1.5S + 0.4W 0.9D + 1.4W + 0.5S plus D,S and D,W	3 4
D,L,W,S	D,L,S; D,L,W; and D,W,S; (no combinations with all of L, S, W)

¹These combinations will only be created if not on an exterior surface - refer to the setting for this feature.

Sustained Live Loads Ls and Lf

Sustained live loads are not in this table. Refer to the note on sustained live loads under the Ultimate Limit States Combinations table, or the note on Dead Load Resisting Failure Combinations under the Sustained Load combinations table.

Dead Loads Due to Soil

Dead load due to soil cannot be used to resist failure according to NBC 4.1.4.1 6) and A4.1.4.1 6) , so no counteracting load combinations are created with Ds

Hydrostatic Loads

The load combinations for hydrostatic loads H can be arrived at by adding H to each of these combinations, while also retaining the combinations without H.

Earthquake Loads

There is no dead-load resisting failure combination for earthquake loads E, as the dead load factor for E is always 1.0, not 1.25 or 0.9. No extra load combinations will be created for E.

Pattern Loads

Dead-load-resisting failure combinations are patterned whenever the corresponding ultimate limit state combination is patterned.

The load types referred to here are D=dead W=wind S=snow H=earth,groundwater E=earthquake L=live(use,occupancy) Ls=live(storage,equipment) Lf =live(controlled fluids) ) Ds=dead load due to soil.