|
|
|
|
|
Serviceability load combinations used by Sizer for deflection design are taken from NBC 2020, Table 4.1.3.4 . The following NBC Structural Commentaries have also been consulted:
CSA O86-14 Section 5.2.4.2 and.Table 5.2.4.2 are used for load combinations when selecting design code options previous to NBC 2020..
The following table gives the serviceability load combinations used for design for total elastic deflection (CSA O86-14 5.5.2) with the Sizer Load types D, L, S and W. The comments below the table explain how to extend this to the load types Ds, Lt/s, H and E.
For the modifications to these combinations to deal with live deflection and permanent deflection (5.5.3) refer to Deflection Design.
Load Type |
Combination |
Case |
D |
1.0D |
1 |
D,L |
1.0D + 1.0L plus D only |
2 |
D,S |
1.0D + 1.0S plus D only |
3 |
D,W |
1.0D + 1.0W plus D only |
4 |
D,L,W |
1.0D + 1.0L + 0.3W 1.0D + 1.0W + 0.35L plus D,L; D,W, and D |
2 4 |
D,L,S2 |
1.0D + 1.0L + 0.35S2 1.0D + 1.0S + 0.35L2 plus D; D,L and D,S |
2 3 |
D,S,W |
1.0D + 1.0S + 0.3W 1.0D + 1.0W + 0.35S plus D; 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) |
|
1Note that this creates two extra load cases by splitting up D + S and D + L compared to what is required by the design code.
2These combinations will only be created if not on an exterior surface -refer to the setting for this feature.
Dead Loads Due to Soil
The load combinations for Dead (soil) load types are arrived at by replacing D with D + Ds in this table, without repeating the load combinations for D only. The main Load Combinations page gives a list of serviceability combinations that contain 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. Refer to Hydrostatic Load Combinations for a list of these combinations and explanation.
Storage Live Loads Ls and Lt
Storage live loads are not included in this table. In general, Replace L by L + Ls or L + Lt if such loads occur, with the appropriate factors, without also repeating all of the load combinations that have L only, or creating combinations with Ls only. An exception to the above is that the load combinations D (+ Ds + H) + L and D ( + Ds + H) + Ls will be created.
In other words, for D, L, Ls, S, the following are created:
And the following are not created:
Refer to Live Storage Load Combinations for a complete list of live storage load combinations for ultimate limit states design and explanation. These correspond to the serviceability states, with the appropriate change in principal factors, with the following exception:
For the permanent deflection check the program will only check those combinations for which the live storage load for liquids in tanks Lt is the principal load. This will govern over the cases that it is the companion load, as D, Ds, and Lt are generally in the same direction and not oriented as H is.
Earthquake Loads
Serviceability load combinations are not created for Earthquake load types, and deflection design is not done for earthquake load combinations.
Pattern Loads
Serviceability 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) Lt =live(liquids in tanks) ) Ds=dead load due to soil.