Using experimental data to reduce the single-building sigma of fragility curves: case study of the BRD tower in Bucharest, Romania

Abstract

Sponsor: Vulnérabilité des Ouvrages aux Risques VOR Program, Rhône-Alpes Council. Acknowledgment:This work was supported by the Rhône-Alpes Regional Council (Programme Vulnerabilité des Ouvrages aux Risques) and the Joseph Fourier Université (Grenoble 1).Using experimental data to reduce the single-building sigma of fragility curves: case study of the BRD Tower (Bucharest -Romania) ABSTRACT:The lack of knowledge concerning modelling existing buildings leads to significant variability in fragility curves for single or grouped existing buildings. This paper aims to investigate the uncertainties of fragility curves, with special consideration of the single-building sigma. Experimental data and simplified models are applied to the BRD tower in Bucharest (Romania), a RC building with permanent instrumentation. A 3-step methodology is applied, (1) adjustment of a linear MDOF model for experimental modal analysis using a Timoshenko beam model and based on Anderson s criteria, (2) computation of the structure s response to a large set of accelerograms simulated by SIMQKE software, considering twelve ground motion parameters as intensity measurements (IM), and (3) construction of the fragility curves by comparing numerical interstorey drift with the threshold criteria provided by the Hazus methodology for the slight damage state. By introducing experimental data into the model, uncertainty is reduced to 0.02 considering Sd(f 1 ) as seismic intensity IM and uncertainty related to the model is assessed at 0.03. These values must be compared with the total uncertainty value of around 0.7 provided by the Hazus methodology.

Correlation between Ground Motion and Building Response using California Earthquake Records

“…Even if the fifth class corresponding to the strongest values lacks data to have a perfect uniform distribution of PGA, this figure confirms the log-normal distribution assumption, considering to represent the vulnerability of existing buildings through fragility curves, i.e. giving the probability to observe a certain level of damage (through NRRD for example) with respect to ground motion intensity (IMs) (e.g., FEMA, 1999;Milutinovic and Trendafiloski, 2003;McGuire, 2004;Calvi et al, 2006;Michel et al, 2012;Perrault et al, 2013). The same result is observed whatever the IM.…”

“…Higher values are expected with higher ground motions, but these values may come from the method, which may not be sufficiently robust. Perrault et al (2013) showed the significant effect of the variation of damping values on fragility functions. Without additional information on the relevancy of this estimate, it is difficult to adopt other solution for setting damping values.…”

Application of a Damage State Method Based on Period Elongation for Time Variant Vulnerability of Degrading Reinforced Concrete Buildings

“…The scatter of the results is higher in the case of the C2M model, which can be seen both visually and by comparing the values (0.95 versus 0.81) of the coefficient of determination (R 2 ). A possible explanation for this is the adoption of PGA as an intensity measure [30]. We are proposing an alternative grouping which gives the probability of exceedance of a specific damage state given that the building is in all lower damage states.…”

Using full bridge numerical model to develop analytical fragility curves

“…Vosooghi et al [17] used data from 32 bridge column test models to develop fragility curves. Perrault et al [18] used experimental data to evaluate the fragility of the BRD tower in Bucharest. Choi et al [19] used RC column experimental results to develop nonlinear models.…”