Displacement-based assessment of typical Italian RC bridges

For the effective management and maintenance of a transport network it is important to identify the most at-risk bridges within the network and subsequently implement efficient retrofit solutions. The risk assessment process adopted for this purpose usually makes use of vulnerability or fragility functions that may be either simple empirical expressions or bridge-specific expressions developed from time-consuming non-linear dynamic analyses. Fragility curves defined for bridge taxonomies are less precise because fragility curves are in general site and bridge dependent. In this work the possibility of using a simplified displacement-based assessment (DBA) procedure for the identification of bridge fragility functions is explored. The simplifications to the DBA approach are made so that the inputs required for assessment are limited to bridge characteristics that can be readily identified from a rapid visual inspection of the bridge (or from drawings). Nonetheless, by incorporating a number of input parameters that can dictate the displacement capacity of a bridge, it is argued that the simplified DBA procedure can still provide a good level of accuracy, particularly compared to simplified empirical methods. In addition to this, for portfolio risk assessment, this approach can be easily applied and is more refined than the use of fragility curves defined for bridge taxonomies. This is demonstrated in the paper by comparing fragility functions obtained via various methods, for a number of RC bridge typologies commonly found in Italy.