Estimation of Building Response to Past
Earthquakes through Structural Identification
Research Team: Babak Moaveni (PI), Andrea Belleri (visiting post-doc
from University of Bergamo, Italy)
Duration: 5/2012 – present
Relevant publications to date:
Belleri, A., Moaveni, B., and Restrepo, J.I. (2014). "Damage assessment through
structural identification of a large-scale three-story precast concrete structure."
Earthquake Engineering and Structural Dynamics, 43(1), 61-76.
The objective of this study is to predict the unmeasured response of a
structure to a recent ground motions based an equivalent linear model of the
structure identified using its response to low-amplitude after-shocks or even
ambient excitations. Such a model can provide an estimate of displacement and
acceleration response measurements. These measurements can be used to compute
inter-story drift and/or shear that are indicative of damage sustained by the
structure during the last earthquake.
A stochastic subspace identification method will be used to realize an
equivalent linear state-space model of a three-story, half scale, precast concrete
building resembling a parking garage (see Figure 1) that was tested on the large
outdoor shake table at the University of California, San Diego. Identification
will be performed based on the low-amplitude white-noise and "after-shock" base
excitation tests and the realized models will be used to predict the structural
response to a damaging earthquake test preceding the low-amplitude base excitations.
This testing program on a precast concrete structure provides a unique
opportunity to use dynamic data obtained from a complex large scale system at
various levels of realistically induced damage. Such data cannot be reproduced
by numerical simulation, where damage is highly idealized in the form of section
reductions of structural members and/or sudden changes in boundary conditions.
The loading sequence was designed to induce damage in the specimen progressively
through scaled historical earthquake ground motions of increasing intensity.
Between the seismic tests, the tested structure was subjected to low-amplitude
white-noise base excitation and to small earthquake type excitations. The specimen
responded to the white-noise and small earthquake base excitations as a quasi-linear
system with modal properties changing as a result of damage and of retrofitting.
Figure 1. Half-scale precast concrete structure tested on the UCSD-NEES shake table