Gravity load designed (GLD) reinforced concrete (RC) buildings represent a common
type of construction in the Mid-America Region. These buildings have limited lateral
resistance and are susceptible to story mechanisms during earthquake loading. Fragility
estimates are developed to assess the seismic vulnerability of GLD RC buildings in the
Mid-America Region. Fragility is defined as the conditional probability of reaching or
exceeding a performance level for a given earthquake intensity measure.
Five sample buildings of various story heights (1, 2, 3, 6, and 10 stories) are used to
represent generic RC frame buildings of 1 to 10 stories tall. A Bayesian methodology is
used to develop probabilistic demand models to predict the maximum inter story drift
given the spectral acceleration at the fundamental period of the building. The unknown
parameters of the demand models are estimated using the simulated response data
obtained from nonlinear time history analyses of the structural models for a suite of
synthetic ground motions, developed for Memphis, Tennessee. Seismic structural
capacity values are selected corresponding to the performance levels or damage states as
specified in FEMA-356 and as computed by nonlinear pushover analyses.
For the sample buildings, fragility estimates are developed using the predicted drift
demands and structural capacity values. Confidence bounds are developed to represent
the epistemic uncertainty inherent in the fragility estimates. In addition, bivariate fragility estimates, formulated as a function of spectral acceleration and the fundamental
building period, are developed from the fragility estimates of the individual buildings.
The bivariate fragilities can be used to quantify the seismic vulnerability of GLD RC
frame buildings of 1 to 10 stories. Using the Bayesian approach, a framework is
developed to update the analytical fragility estimates using observed damage data or
experimental test data. As an illustration of the updating framework, the analytical
bivariate fragility estimates for the sample buildings in the Mid-America Region are
updated using the damage data obtained from 1994 Northridge, California earthquake.
Furthermore, to investigate and demonstrate the increase in seismic performance
of the GLD RC frame buildings, the columns of the 2 and 3 story buildings are
retrofitted by column strengthening. Fragility estimates developed for the retrofitted
buildings show the effectiveness of the retrofit technique by the improved seismic
performance of GLD RC frame buildings.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4937 |
| Date | 25 April 2007 |
| Creators | Ramamoorthy, Sathish Kumar |
| Contributors | Bracci, Joseph M., Gardoni, Paolo |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 1601625 bytes, electronic, application/pdf, born digital |
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