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ACI 318-19 default load combinations

This section provides information on the default load combinations (technically, loading combinations) that RAM Concept creates when you start a new ACI 318-14 file. The purpose and origin of each load combination are given. You can remove or modify any of these load combinations. You can also add load combinations. The load combinations are from ACI 318-14 /ASCE 7-10 unless noted otherwise.

RAM Concept uses loading types to determine the appropriate factors in some load combinations. The factor on "L" in ACI 318-14 equations (5.3.1c), (5.3.1d), and (5.3.1e) will be equal to 0.5 for Live (Reducible) Loading, 1.0 for Live (Unreducible) Loading, 1.0 for Live (Storage) Loading, and 1.0 for Live (Parking) Loading.

For the default Load History specification, RAM Concept uses the "Service LC: D + L" combination for the maximum load case. This load combination does not contain any roof loads. For floors that contain roof loads, a more appropriate load combination will need to be specified for the maximum load history step.

Note: Some load combinations in mat (raft) files are of the Lateral Group type and use a "Zero-Tension" analysis. Since a load combination using a "Zero-Tension" analysis does not use Alternate Envelope Factors, then such load combinations in mat files have been expanded into multiple load combinations. In some cases, the assumption that all gravity loads act in the same direction have been used to keep the number of load combinations to a minimum. See Specifying Load Combinations for further description.
Parent topic: ACI 318-19 Design

All Dead LC

This load combination sums all of the dead loadings, with a load factor of 1.0, that act simultaneously in the standard service condition. This load combination is for information only - it is not used by RAM Concept for design purposes.

Initial Service LC

This load combination is intended for checking requirements upon application of prestress. The load factors used are:

Balance Loading: 1.13 (std & alt) (this includes an 13% increase for long-term losses, which have normally not occurred at this stage)

Note: Although elastic shortening produces a short-term loss, in RAM Concept elastic shortening losses are considered part of the long term loss lump sum.

Self-Dead Loading: 1.0 (std & alt)

Temporary Construction Loading (At Stressing): 1.0 (std & alt)

Service LC: D + L

This load combination is intended for checking the serviceability limit state. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 1.0 (std) & 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) & 0.0 (alt)

Live (Storage) Loading: 1.0 (std) & 0.0 (alt)

Live (Parking) Loading: 1.0 (std) and 0.0 (alt)

Service LC: D + Lr

This load combination is intended for checking the serviceability limit state. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Roof) Loading: 1.0 (std) & 0.0 (alt)

Service LC: D + S

This load combination is intended for checking the serviceability limit state. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Snow Loading: 1.0 (std) & 0.0 (alt)

Service LC: D + 0.75L + 0.75Lr

This load combination is intended for checking the serviceability limit state. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.75 (std) & 0.0 (alt)

Live (Unreducible) Loading: 0.75 (std) & 0.0 (alt)

Live (Storage) Loading: 0.75 (std) & 0.0 (alt)

Live (Parking) Loading: 0.75 (std) and 0.0 (alt)

Live (Roof) Loading: 0.75 (std) & 0.0 (alt)

Service LC: D + 0.75L + 0.75S

This load combination is intended for checking the serviceability limit state. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.75 (std) & 0.0 (alt)

Live (Unreducible) Loading: 0.75 (std) & 0.0 (alt)

Live (Storage) Loading: 0.75 (std) & 0.0 (alt)

Live (Parking) Loading: 0.75 (std) and 0.0 (alt)

Snow Loading: 0.75 (std) & 0.0 (alt)

Sustained Service LC

This load combination is intended for checking the serviceability limit state. For the purpose of this load combination, 100% of the Live (Storage) Loading and 50% of all other live loading is assumed to be permanent loading. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.5 (std & alt)

Live (Unreducible) Loading: 0.5 (std & alt)

Live (Storage) Loading: 1.0 (std & alt)

Live (Parking) Loading: 0.5 (std) and 0.0 (alt)

Live (Roof) Loading: 0.5 (std & alt)

Factored LC: 1.4D

This load combination is intended for checking the strength limit state. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.4 (std) and 0.9 (alt)

Factored LC: 1.2D + 1.6L + 0.5Lr

This load combination is intended for checking the strength limit state. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) and 0.9 (alt)

Live (Reducible) Loading: 1.6 (std) and 0.0 (alt)

Live (Unreducible) Loading: 1.6 (std) and 0.0 (alt)

Live (Storage) Loading: 1.6 (std) and 0.0 (alt)

Live (Parking) Loading: 1.6 (std) and 0.0 (alt)

Live (Roof) Loading: 0.5 (std) and 0.0 (alt)

Factored LC: 1.2D + f1L+ 1.6Lr

This load combination is intended for checking the strength limit state. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) and 0.9 (alt)

Live (Reducible) Loading: 0.5 (std) and 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) and 0.0 (alt)

Live (Storage) Loading: 1.0 (std) and 0.0 (alt)

Live (Parking) Loading: 1.0 (std) and 0.0 (alt)

Live (Roof) Loading: 1.6 (std) and 0.0 (alt)

Factored LC: 1.2D + 1.6L + 0.5S

This load combination is intended for checking the strength limit state. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) and 0.9 (alt)

Live (Reducible) Loading: 1.6(std) and 0.0 (alt)

Live (Unreducible) Loading: 1.6 (std) and 0.0 (alt)

Live (Storage) Loading: 1.6 (std) and 0.0 (alt)

Live (Parking) Loading: 1.6 (std) and 0.0 (alt)

Snow Loading: 0.5 (std) and 0.0 (alt)

Factored LC: 1.2D + f1L+ 1.6S

This load combination is intended for checking the strength limit state. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) and 0.9 (alt)

Live (Reducible) Loading: 0.5 (std) and 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) and 0.0 (alt)

Live (Storage) Loading: 1.0 (std) and 0.0 (alt)

Live (Parking) Loading: 1.0 (std) and 0.0 (alt)

Snow Loading: 1.6 (std) and 0.0 (alt)

Service Wind LC: D + 0.6W

This load combination is intended for checking the serviceability limit state with applied wind loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Ultimate Wind Loading: 0.6 (std & alt)

Service Wind LC: D + 0.75L + 0.75Lr + 0.45W

This load combination is intended for checking the serviceability limit state with applied wind and live loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.75 (std & alt)

Live (Unreducible) Loading: 0.75 (std & alt)

Live (Storage) Loading: 0.75 (std & alt)

Live (Parking) Loading: 0.75 (std & alt)

Live (Roof) Loading: 0.75 (std & alt)

Ultimate Wind Loading: 0.45 (std & alt)

Service Wind LC: D + 0.75L + 0.75S + 0.45W

This load combination is intended for checking the serviceability limit state with applied wind and live loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.75 (std & alt)

Live (Unreducible) Loading: 0.75 (std & alt)

Live (Storage) Loading: 0.75 (std & alt)

Live (Parking) Loading: 0.75 (std & alt)

Snow Loading: 0.75 (std & alt)

Ultimate Wind Loading: 0.45 (std & alt)

Service Wind LC: 0.6D + 0.6W

This load combination is intended for checking the serviceability limit state with applied wind loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 0.6 (std & alt)

Ultimate Wind Loading: 0.6 (std & alt)

Service Seismic LC: D + 0.7E

This load combination is intended for checking the serviceability limit state with applied seismic loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Ultimate Seismic Loading: 0.7 (std & alt)

Service Seismic LC: D + 0.75L + 0.75S + 0.525E

This load combination is intended for checking the serviceability limit state with applied seismic and live loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 1.0 (std & alt)

Live (Reducible) Loading: 0.75 (std & alt)

Live (Unreducible) Loading: 0.75 (std & alt)

Live (Storage) Loading: 0.75 (std & alt)

Live (Parking) Loading: 0.75 (std & alt)

Snow Loading: 0.75 (std & alt)

Ultimate Seismic Loading: 0.525 (std & alt)

Service Seismic LC: 0.6D + 0.7E

This load combination is intended for checking the serviceability limit state with applied seismic loads. It is currently only generated for mat foundations. The load factors used are:

Balance Loading: 1.0 (std & alt)

Dead Loading: 0.6 (std & alt)

Ultimate Seismic Loading: 0.7 (std & alt)

Factored Wind LC: 1.2D + f1L + 0.5Lr + W

This load combination is intended for checking the strength limit state with applied wind and live loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) & 0.9 (alt)

Live (Reducible) Loading: 0.5 (std) & 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) & 0.0 (alt)

Live (Storage) Loading: 1.0 (std) & 0.0 (alt)

Live (Parking) Loading: 1.0 (std) & 0.0 (alt)

Live (Roof) Loading: 0.5 (std) & 0.0 (alt)

Ultimate Wind Loading: 1.0 (std & alt)

Factored Wind LC: 1.2D + f1L + 0.5S + W

This load combination is intended for checking the strength limit state with applied wind and live loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) & 0.9 (alt)

Live (Reducible) Loading: 0.5 (std) & 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) & 0.0 (alt)

Live (Storage) Loading: 1.0 (std) & 0.0 (alt)

Live (Parking) Loading: 1.0 (std) & 0.0 (alt)

Snow Loading: 0.5 (std) & 0.0 (alt)

Ultimate Wind Loading: 1.0 (std & alt)

Factored Wind LC: 1.2D + 1.6Lr + 0.5W

This load combination is intended for checking the strength limit state with applied wind and live loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std & alt)

Live (Roof) Loading: 1.6 (std & alt)

Ultimate Wind Loading: 0.5 (std & alt)

Factored Wind LC: 1.2D + 1.6S + 0.5W

This load combination is intended for checking the strength limit state with applied wind and live loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std & alt)

Snow Loading: 1.6 (std & alt)

Ultimate Wind Loading: 0.5 (std & alt)

Factored Seismic LC: 1.2D + f1L + 0.2S + E

This load combination is intended for checking the strength limit state with applied seismic and live loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 1.2 (std) & 0.9 (alt)

Live (Reducible) Loading: 0.5 (std) & 0.0 (alt)

Live (Unreducible) Loading: 1.0 (std) & 0.0 (alt)

Live (Storage) Loading: 1.0 (std) & 0.0 (alt)

Live (Parking) Loading: 1.0 (std) & 0.0 (alt)

Snow Loading: 0.2 (std) & 0.0 (alt)

Ultimate Seismic Loading: 1.0 (std & alt)

Factored Seismic LC: 0.9D + E

This load combination is intended for checking the strength limit state with applied seismic loads. The load factors used are:

Hyperstatic Loading: 1.0 (std & alt)

Dead Loading: 0.9 (std & alt)

Ultimate Seismic Loading: 1.0 (std & alt)