Question about ductility in buildings

[afdengo]

I've noticed in my structural engineering coursework that it is important (especially in seismic zones) to design steel and concrete buildings with the ability to dissipate energy through ductility. However,what I do not fully understand is that if we design members to yield and develop hinges in large scale events, what is done with these buildings afterwards.

It seems easier in a steel building where you can design a moment frame with a reduced beam section as a structural fuse, you could just go and change that member later I guess. But what do you do with a concrete structure that has yielded?

 

[JAE]

Building codes are focused on Life Safety and not Building Survival....unless the owner wants the structure to fully survive a seismic event of some designated magnitude.

As such, after a major seismic event where a structure has performed as planned, lives are saved but the structure may or may not be salvageable.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[structSU10]

I want to piggy back on this question a bit, as it is something I have wondered about a bit myself.

Lets say you design a building in CA according to ASCE 7 and AISC 341. A major seismic event happens. fuse elements yield/buckle and dissipate the energy of the event, and the building looks fine to a non engineer but it may be deficient if another event were to happen and requires repairs. Is there some form of inspection mandated by the state that would uncover if the building needs to have structural repairs? Is it standard for all owners to have an inspection done after a major event just in case, even if no evidence of damage to the structure is readily apparent?

Do owners all know their buildings are potentially designed for one major event, and it may need to be demolished even if it 'survives'? I assume some discussion of performance based design is brought up in the design phase.

I assume non-structural stuff needs work, and maybe when people dig into that they run into 'spent' structural members, but it may not be obvious to an untrained eye.