## LRFD vs LFD

## LRFD vs LFD

(OP)

What is the difference between LRFD (load and resistance factor design) and LFD (load factor design)?

For loads (dead, live, etc.) apply a "load factor" such as:

1.4D

1.2D + 1.6L

The "resistance factor" is the phi for bending, compression, tension, etc.

Does LFD simply not use the "reduction factor" and LRFD does?

For loads (dead, live, etc.) apply a "load factor" such as:

1.4D

1.2D + 1.6L

The "resistance factor" is the phi for bending, compression, tension, etc.

Does LFD simply not use the "reduction factor" and LRFD does?

## RE: LRFD vs LFD

DaveAtkins

## RE: LRFD vs LFD

LFD is load factor design - meaning all safety factors are applied to the load. The factored load can be as high as the ultimate load.

LFRD is load factor resistance design - meaning safety factors are applied to both the load (demand) and to the materials (resistance). In theory, the factors (load and resistance) should be based on statistical analysis to determine the possible range of loads and possible range of resistance offered by the materials coupled with appropriate factors of safety.

Hope this is helpful

KEW

## RE: LRFD vs LFD

Then, out of curiousity, the ACI 318-02 is all based on LRFD. To modify it for LFD, should I just ignore all the phi factors?

## RE: LRFD vs LFD

## RE: LRFD vs LFD

## RE: LRFD vs LFD

## RE: LRFD vs LFD

## RE: LRFD vs LFD

1.2DL+1.6LL<phi*N

where phi is the reduction factor and N is the nominal resistance. So you'd just divide both sides of the equation by phi to get the same factor of safety as using LRFD.

## RE: LRFD vs LFD

Hg

Eng-Tips guidelines: FAQ731-376

## RE: LRFD vs LFD

## RE: LRFD vs LFD