PSI - Issue 62

Mariano Angelo Zanini et al. / Procedia Structural Integrity 62 (2024) 815–823 Zanini / Structural Integrity Procedia 00 (2019) 000 – 000

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As regards the MIT EV loading scheme considered, results highlight how structural demands both in BM and S parameters are higher than those derived from the traffic load models almost for all the girder deck configurations designed from 1930 to 2005 in the case of free traffic conditions and also when speed limitation of the EV is introduced. If the suspension of the traffic is introduced, L3EV coefficients shows values closed to the unitary value for the shorter span length configurations in the interval 1952-2023, whereas for the longer ones structural demands are higher. Traffic suspension measure coupled with the use of geometric limitations lead to structural demands lower than those used for the design of the majority of the analysed girder deck configurations in the interval 1952-2023. The most critical configurations are instead represented by girders with short span lengths built before 1952, where the L3EV coefficient can reach values higher than 3. As regards the real EV configurations analysed, the S10 EV loading scheme herein reported for sake of example highlights similar outcomes than those described for the MIT EV 1080/135 loading scheme. From the analysis of the resulting L3EV coefficients, the main influencing parameters on the structural demand are the year of the design that reflects the traffic load model adopted in the design code in force at that time, and the span length of the girder deck, whereas the number of beams and the deck width have shown a significantly lower impact. In addition, from the observation of Figs. 4-7 it is possible to note three different macro-steps characterizing the temporal evolution of L3EV coefficients, that can be associated to the regulations in force in the time intervals 1933 1951, 1952-2004 and 2005-2023. In order to provide a quick aid to infrastructure owners in responding about the transitability over a stock of existing bridges belonging to the requested travel itinerary, the L3EV coefficient plots over time can be used to get a preliminary suggestion on its feasibility. A further results processing has been carried out by grouping the L3EV coefficients in a set of subclasses defined in relation to the type of EV loading scheme, design code and span length interval, computing mean and standard deviation values of L3EV coefficients, and to get a judgment on the similarity of the structural demand induced by the EV loading scheme with that of the traffic load model of the code in force to be used as a preliminary “ fast transitability judgment ” . In detail, the following intervals have been considered: - L3EV < 0.7 stands for a structural demand of the EV “LOW” with respect to the design one; - 0.7 < L3EV < 1.3 represents case where the structural demand of the EV is “SIMILAR” with respect to the design one; - 1.3 < L3EV < 2.0 is associated to configurations where the structural demand of the EV is “HIGHER” with respect to the design one; - 2.0 < L3EV characterizes conditions where the structural demand of the EV is “MUCH HIGHER” than the design one. As regards the judgement attributed to the dispersion of the L3EV results (i.e. standard deviation value), the following judgement have been set: - St. dev. < 0.05 is associated to “LOW” dispersion; - 0.05 < St. dev. < 0.10 stands for “MEDIUM” dispersion; - 0.10 < St. dev. is as signed to “HIGH” dispersion. Table 1 shows as sake of example the judgments that can be assigned to different types of girder decks designed with the code of 1990 with respect to the bending moment actions induced by a request of transit of the S10 EV loading scheme.

Table 1. Fast transitability judgments based on L3EV coefficients – BM case.

BENDING MOMENT - LEVEL 3 COEFFICIENT - 1990

L < 10 m

10 m ≤ L < 20 m

20 m ≤ L < 30 m

30 m ≤ L < 40 m

L > 40 m

Mean Dispersion Mean Dispersion Mean Dispersion Mean Dispersion Mean Dispersion TF Similar Mean Higher High Higher Low Higher Low Higher Low TS Similar Mean Similar High Higher Mean Higher Mean Higher Mean TSGL Low Mean Similar Mean Similar Mean Similar Mean Similar Mean S10