PSI - Issue 84

Stefano Bozza et al. / Procedia Structural Integrity 84 (2026) 852–858

854

numbers of transverse diaphragms equal to two or three were considered. For each deck width, three different number of main girders were taken into account, in order to obtain beam spacing as close as possible to 1.0 m, 2.0m and 3.0 m. Beams were assumed equally spaced along the deck width. Moreover, different beam sections were considered, chosen from a section database made of 19 precast sections with height varying from 0.6 m to 2.0 m; for each deck length, every section with height between 1/22 of the span and 1/15 of the span was considered. Overall, a total of 42480 deck geometries were taken into account. 2.2. Traffic load models The evolution of the Italian codes on traffic loads have been investigated in previous studies (Buratti et al. (2019), Bencivenga et al. (2022), Bozza et al. (2023)), so it is not reported for sake of brevity. In the present paper, the following regulations and the following specified bridge class were considered: • Decree no. 8 of September 15, 1933 (D. 1933), first and second class bridges (neglecting third class bridges); • Circular no. 6018 of June 09, 1945 (C. 1945), only first class bridges; • Circular no. 384 of February 14, 1962 (C. 1962), first and second class bridges; • Ministry Decree no. 308 of August 02, 1980 (D.M. 1980), first and second class bridges; • Ministry Decree of May 04, 1990 (D.M. 1990), first and second class bridges; • Ministry Decree no. 222 of September 14, 2005 (D.M. 2005), first and second class bridges; • Ministry Decree no. 29 of January 14, 2008 (D.M. 2008), first and second class bridges; • Ministry Decree no. 8 of January 17, 2018 (D.M. 2018), only first class bridges (reference traffic load model). Every regulation specifies different lane loads, lane widths, sidewalks load, and dynamic amplification factors, explicitly taken into account in the parametric study. Deck geometries described in section 2.1 were analysed with every regulation reported above, following the simplified structural analysis described in section 2.3. In the present paper, the simplified structural analysis of the bridge decks adopted take into account the transverse load distribution via the methodology proposed by Guyon, Massonnet and Bareš (Massonnet and Bareš (1966)). The structural behaviour of a simply supported deck made of longitudinal main girders and transverse diaphragms is approximate as an equivalent orthotropic plate, characterised by a torsional parameter and a transverse deformability parameter , defined as: = + 2√ ∙ , = √ 4 (1) Where is the span length, b is the half-width of the deck, , are the torsional stiffness per unit of width of longitudinal girders and transverse diaphragms, and , are the bending stiffness per unit of width of longitudinal girders and transverse diaphragms . Guyon, Massonnet and Bare š derived the coefficients that allow to calculate the stresses on the equivalent orthotropic plate induced by sinusoidal loads for the cases α = 0 and α = 1, and proposed an interpolation for intermediate values of . In the present work, the coefficient related to the transverse distribution of bending moments induced by a sinusoidal load with a half sine wave of length is used to evaluate the transverse distribution of equivalent uniformly distributed loads, which were used instead of the exact lane load model, as described in Bozza et al. (2023). For each geometry, the maximum bending moment in the most stressed girder was calculated for each traffic load model. Then, all the results for outdated regulation were normalised to the reference values, i. e. the maximum bending moments induced by the current technical code (D.M. 2018). The normalised data represent the comparison between effects induced by outdated traffic load model and those induced by current technical code, that is a preliminary assessment according to the Guidelines. 2.3. Simplified structural analyses