The Effective Fragility Analysis (EFA) methodology is applied to the assessment of seismic reliability of three reinforced concrete bridges along Italian highway network. The selected bridges are different for structural scheme (continuous/simply supported deck) and pier type (single stem/frame piers). The reliability evaluation considers different sources of uncertainty: in the seismic input, through the use of different accelerograms for the dynamic analysis, in the structural behaviour, through the use of a refined non-linear finite element model, and in the ultimate state modelling. The EFA procedure implemented in this study reduces the number of simulations required for the reliability analysis using a surface response technique only for random variables affecting the structural dynamic behaviour, whilst state-limit randomness is treated explicitly during simulations. The final result of the analysis is the bridge fragility curve as function of spectral acceleration and, through its convolution with local hazard, the risk. Those results are briefly discussed with respect to the following aspects: comparison of bridge vulnerability in relation of different pier and deck structural models, influence of material randomness on final reliability, relative importance of seismic input respect to mechanical and epistemic uncertainty.
A probabilistic approach for seismic assessment of r.c. structures: application to highway bridges
RASULO, Alessandro
2004-01-01
Abstract
The Effective Fragility Analysis (EFA) methodology is applied to the assessment of seismic reliability of three reinforced concrete bridges along Italian highway network. The selected bridges are different for structural scheme (continuous/simply supported deck) and pier type (single stem/frame piers). The reliability evaluation considers different sources of uncertainty: in the seismic input, through the use of different accelerograms for the dynamic analysis, in the structural behaviour, through the use of a refined non-linear finite element model, and in the ultimate state modelling. The EFA procedure implemented in this study reduces the number of simulations required for the reliability analysis using a surface response technique only for random variables affecting the structural dynamic behaviour, whilst state-limit randomness is treated explicitly during simulations. The final result of the analysis is the bridge fragility curve as function of spectral acceleration and, through its convolution with local hazard, the risk. Those results are briefly discussed with respect to the following aspects: comparison of bridge vulnerability in relation of different pier and deck structural models, influence of material randomness on final reliability, relative importance of seismic input respect to mechanical and epistemic uncertainty.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
