PSI - Issue 62

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

818

4

In order to analyse the highest number of possible configurations, in addition to the EV loading schemes provided by the MIT EV standard, a set of real EV configurations has been considered representative of types of vehicles commonly used by transport companies. Fig. 2 illustrates EV schemes investigated, characterized by a number of axles higher than 8, thus implying the possibility to transport total weights higher than those defined by the MIT EV standard. For each case, Fig. 2 lists main data retrievable in the technical data sheets of the vehicles, in terms of distances between consecutive axles as well as maximum loads admissible per axle.

Fig. 2. EV loading schemes for real types of vehicles used by transport companies.

For these additional loading schemes the following scenarios have been considered:

• Free traffic : bridge is considered open to traffic; as a consequence, the structural demand calculation is carried out considering the EV placed in the first lane, while the remaining lanes are loaded with the loads foreseen by the current Codes (MIT 2018). • Suspended traffic : in this case, the EV passing in the first lane is always considered, while the remaining lanes are empty as the bridge is considered closed to traffic. • Suspended traffic and transversal geometric limitation : in this case, the EV is positioned in the center of roadway, i.e. the most favorable transversal position, whereas the remaining area is unloaded, given that the bridge is considered closed to traffic. 3. Methodology For the computation of the “Level 3 coefficient for EV loads” the Engesser-Courbon theory for the transverse distribution of dead and live loads on girder decks has been adopted. This approach underlies some key assumptions, i.e. that transverse beams have to be considered able to allow the transversal distribution of loads, thus meaning that are characterized by a significative bending stiffness; and longitudinal beams have to be considered responding to loads in a pure bending deflection mode, without torsional effects. Under such hypotheses, a girder deck subject to gravitational loads is able to distribute among longitudinal beams the resulting solicitation, and will have a transversal deformation profile of a linear type; and the transversal distribution of loads among the longitudinal beams is