  The authors propose a seismic monitoring framework for instrumented buildings
that employs dissipated energy as a feature for damage detection and
localization. The proposed framework employs a nonlinear model-based state
observer, which combines a nonlinear finite element model of a building and
global acceleration measurements to estimate the time history of seismic
response at all degrees of freedom of the model. This includes displacements,
element forces, and plastic deformations in all structural members. The
estimated seismic response is then used to 1) estimate inter-story drifts and
determine the post-earthquake re-occupancy classification of the building based
on performance-based criteria, 2) compare the estimated demands with code-based
capacity and reconstruct element-by-element demand-to-capacity ratios and 3)
reconstruct element-level normalized energy dissipation and ductility. The
outcome of this process is employed for the performance-based monitoring,
damage detection, and localization in instrumented buildings. The proposed
framework is validated using data from the Van Nuys hotel testbed; a
seven-story reinforced concrete building instrumented by the California Strong
Motion Instrumentation Program (Station 24386). The nonlinear state observer of
the building is implemented using a distributed plasticity finite element model
and seismic response measurements during the 1992 Big Bear and 1994 Northridge
earthquakes. The performance and damage assessment results are compared with
the post-earthquake damage inspection reports and photographic records. The
results demonstrate the accuracy and capability of the proposed framework in
the context of a real instrumented building that experienced significant
localized structural damage.
