Overstrength factor (AS3600-2018)

[DisplayName001]

When ductility is assumed in the model, do we need to times the analysis result by the overstrength factor (say 2.6 for limited ductile) when designing? If so what is the point reducing the seismic force in the first place then? Does AS3600-2018 mention that we need to time the overstrength factor in design cuz I couldn't find it.

 

[KootK]

...do we need to times the analysis result by the overstrength factor (say 2.6 for limited ductile) when designing?

Typically you only need to apply overstrenght to a select number of members within your structure, not all of them.

If so what is the point reducing the seismic force in the first place then?

The point is that it's advantages for all of the members within your structure that do not require overstrength design, which is usually most of them.

 

[rapt]

You cannot find it because the code does not require you to multiply the analysis result by the overstrength factor (say 2.6 for limited ductile) when designing. Why would you do it?

There are a couple of places where decisions on design approach are required to use the full earthquake loading (e.g. to decide if a wall needs to be detailed for tension), not the reduced design loading, but not in the strength requirements.

 

[Retrograde]

You only need to times the analysis result by the overstrength factor when checking lateral drift.