PSI - Issue 44

Gianluca Costantino et al. / Procedia Structural Integrity 44 (2023) 1220–1227 Gianluca Costantino et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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Therefore, in this paper, some assumptions are introduced to fill up this gap and, thus, suggest a procedure to estimate the level of defectiveness as a function of the inspection results. The Guidelines introduce a list of Critical Elements (CEs), indicating with this term the elements that are particularly subject to degradation phenomena and whose possible malfunctions can significantly affect the overall structural behavior of the bridge, i.e. the elements or conditions for which the presence of a high degree of decay should be reported immediately. Here, the list of CEs suggested by the Guidelines has been extended (Section 3.3 of Guidelines 3.3). Indeed, apart from some elements already suggested in the Guidelines, like Gerber saddles, prestressing tendons and extensive crack patterns, others elements have been assumed as critical for the bridge. Some of these are: movements and undermining of foundation, diagonal and crushing cracks, bending of rebars, missing anchor of rebars, oxidation of prestressing wires. Moreover, the level of defectiveness depends on the inspection results. The parameters that should be considered to evaluate the basic level of defectiveness are level (G), extension ( k 1 ) and intensity ( k 2 ) of the detected defects. If G < 4, the level of defectiveness is estimated as medium-low independently of the extension and intensity. In all the others cases (G = 4 or 5), it is evaluated by the matrix proposed in Table 1. In addition, if the defect affects the static of the bridge (AS = true), the basic level of defectiveness is increased and, if the defect involves a CE, the level of defectiveness is always assumed as high .

Table 1. Level of defectiveness: 1) Low, 2) Medium-Low, 3) Medium, 4) Medium-High, and 5) High G k 1 k 2 AS CE 0.2 0.5 1 true true 4 0.2 2 2 3 4 5 4 0.5 2 2 3 4 5 4 1 2 2 5 5 5 5 0.2 3 3 3 4 5 5 0.5 3 3 3 4 5 5 1 3 3 5 5 5

The web platform implements the suggested procedure for the estimation of the level of defectiveness and automatically provides the results in terms of Seismic and Structural/Foundational CoAs. The results in terms of Structural/Foundational and Seismic CoAs are reported in Figs. 5 and 6, respectively. The Structural-Foundational CoA of 19/142 bridges is high , while that of most of the bridges is medium-high . The level of hazard is high for all the bridges investigated here because of the high traffic level frequency on the single lane of the highway (Fig. 5a). The levels of Vulnerability (Fig. 5b) and Exposure (Fig. 5c) are predominantly medium-high (86/142) and medium (66/142), respectively. The results in terms of Seismic CoA show a high level for 38/142 bridges and a medium-high for 86/142. Referring to Fig. 6d, many of the bridges with the higher values of the seismic CoA are localized close to the Messina strait area, where the current Italian code (NTC18) provides a Peak Ground Acceleration (PGA) > 0.25g. The PGA strongly influences the seismic hazard, as shown in Fig. 6a. The seismic exposure is different from the Structural/Foundational exposure because of the strategic classification of the bridge. In the case of the A18 highway, all the bridges can be classified as strategic (i.e. they are involved into the plans of the Italian Civil Protection Department). Then, the exposure factor is predominately medium-high (66/142). The vulnerability, as well as the level of defectiveness above discussed, is influenced by the design criteria of the bridge. For many of the bridges taken into account, the design was carried out without seismic provisions. Therefore, the vulnerability level is predominantly medium-high (102/142). 4. Conclusions The paper presents a web platform for the management and analysis of existing bridges, focused on the approach proposed by the Italian Guidelines, which is applied to a bridge stock located in the Sicilia region (southern Italy).