Page 15 - Advanced Design Examples of Seismic Retrofit of Structures

sources
damage
possibly
are
risk
standby
utilities
lower
less
available,
Much
other
from
and
risk
lack
lower
or
failure
to
and
due
damage
mechanical
operate
utilities
Less
not
of
electrical
damage
risk
damaged
higher
and
more
Target Levels Performance Building Level Operational Occupancy Immediate Level Safety (1-B) Level (1-A) light Very Light drift. permanent No drift. permanent No and strength residual substantially Structure substantially Structure stories. all in left original retains and strength original retains Grav
mechanical,
slightly
are
[6] Life (3-C) Moderate Some stiffness elements of-plane tipping Some Damage Building Falling but systems Somewhat and
Levels Level and permanent blocked. damage
Performance Prevention stiffness residual load-bearing but walls and Large exits Some unbraced and at or failed incipient failure. Building is collapse damage more risk greater
Structural Collapse (5-E) Severe Little strength, columns function. drifts. Infills parapets near Extensive Significantly and
of components for under design
Sample with intended designed (National Hazards Program) the
1.1 Damage Nonstructural NEHRP for
TABLE Overall General Comparison performance buildings the Earthquake Reduction provisions, earthquake