PSI - Issue 44

Fabrizio Paolacci et al. / Procedia Structural Integrity 44 (2023) 697–704 Fabrizio Paolacci et al./ Structural Integrity Procedia 00 (2022) 000–000

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ArcGIS® ESRI programs (Quinci et al 2022). A first version of Building Information Model (BIM) was prepared, with the idea of creating a preliminary BIM model for each bridge, starting from the basic information available (D’Amico et al 2022). Level 1 focused on visual inspections of bridges, whose main goal is to determine the conservation state of the structure, synthetically represented by the defect level. An algorithm for the evaluation of the defect level of each bridge was developed. The procedure, which tried to overcome some of the limitations of the Italian guidelines MIT 17/04/2020 (in which it is still unclear how to go from identifying defects on each bridge element to estimating the defect level of the entire structure) is synthetically described in the following. As a first step special defect sheets are filled in during the visual inspection, in which, for each element of the bridge, each defect is associated with a weight, extension and intensity. Then, an importance-of-defect index, representative of the extent to which the defect is present in the structure is evaluated. Based on this, the defect level of each element of the bridge is calculated. The final output of the procedure is the defect level of the whole structure, obtained by combining the defect levels of all the single elements. This defect level ranges from 1 (low) to 5 (high), passing through three further intermediate classes, that is 2 (medium-low), 3 (medium) and 4 (medium-high). It is worth noting that the defect level of the bridge also considers the importance (weight) of each element in the stability of the structure under static loads, which is an aspect needing attention, as highlighted in Pellegrino et al. 2011.

Fig. 2. Evaluation process of the attention class.

Level 2 aimed to assign to each bridge an attention class, either static or seismic, in order to establish a qualitative mapping of the structures, allowing for the individuation of the most critical ones. The attention class of a bridge is obtained by following the workflow resumed in Fig. 2, based on the combination of three indices: hazard, vulnerability and exposure. For the evaluation of each of these indices, the Italian guidelines MIT 17/04/2020 indicates the characteristics of the structure to be taken into account (Table 1), already acquired in the previous levels and gathered within the database. This procedure allows to classify the bridges in 5 different classes, from the low attention class up to the high attention class.

Table 1. Minimum amount of data for Level 2 analysis. Attention class

Static

Seismic

Hazard

Traffic load allowed Frequency of traffic load

ag (Peak Ground Acceleration T r =50years

T i (Ground category) (a)

Defect level

Span length Materials

Construction age (a) Static scheme Length of the span Materials Number of spans Daily average traffic Average span length Alternative road (a)

Typology of span

Vulnerability

Design method (seismic or not seismic) (a)

Defect level

Daily average traffic

Exposure

Strategic nature of the structure

Bypassed structure (a) (a) Not essential data that can be conservatively replaced by values provided by the Italian guidelines.