Structural Evaluation Criteria.

DOE-STD-3014-96

APPENDIX C

the building would collapse under impact. But a detailed finite element model is

necessary to determine if localized collapse needs to be evaluated.

If the model is also used to compute instructure shock spectra to evaluate the

functionality of SSCs supported by the target structure, the structural components that

support these SSCs should be explicitly represented by separate mass and stiffness

elements. Also, the discretization of mass and stiffness should be refined enough that

the high frequency content of the impact force is appropriately reflected in the generated

instructure spectra.

C.6.3.3.3 Structural Evaluation Criteria.

Even if one or more structural components fail (i.e., the computed ductility ratio is more

than the permissible value), the building or the structure as a whole may not collapse

unless a mechanism (i.e., no resistance to additional load) is formed due to the failure of

these components. To determine if collapse would occur, a nonlinear analysis (having

both geometric and material nonlinearity) can be performed in which the stiffness of the

structural components shall be set approximately to zero as soon as the deformation

reaches the ductility limit. If the structure can withstand the impact force without forming

a mechanism, no structural collapse will occur.

For certain target structures, their deformation, displacement, or strain may be required

to remain within some specified limits well below those associated with the permissible

ductility ratios given in Section 6.3.3.3. Examples of such structures are (1) concrete

structures or vaults that must perform a confinement function and therefore are allowed

only infinitesimal cracks, and (2) structures that must not deform excessively to avoid

pounding on adjacent safety-related systems or structures. Permissible deformation or

strain limits for these structures shall be based on their performance requirements.

C-17