Elastic Seismic Design? 3

[Logan82]

Hi,

From what I have seen, codes typically ask that the building must resist earthquakes of X shake intensity, using inelastic deformations to absorb seismic energy. Inelastic deformations can imply important building damage, but it is cheaper to design using inelastic deformations.

How can we perform seismic design while remaining in the elastic realm and without damaging the building? Does anyone have good references or codes for that kind of design? I am thinking about the kind of design for important buildings such as power plants or hospitals. They are the type of buildings that need to be operational even after the "design earthquake shake" happens.

 

[BridgeSmith]

Other than that, why would a properly designed structure using only elastic deformation for seismic loads be less adequate than a properly designed structure using inelastic deformation?

It's not that elastic design is not as good; it's a matter of what happens when the elastic limit is exceeded. All structures respond elastically up to a point. What you don't want is for the structure to fail catastrophically if an earthquake twice the size of what you designed for hits. In bridge design, we use overstrength factors to control where the failure occurs (concrete components are assumed to be 40% stronger than the design strength when they are the planned failure point). I assume the building code has something similar.

Rod Smith, P.E., The artist formerly known as HotRod10