PSI - Issue 64

Marco di Prisco et al. / Procedia Structural Integrity 64 (2024) 2133–2140 M. di Prisco, L. Radice, M. Colombo / Structural Integrity Procedia 00 (2019) 000 – 000

2136

4

Table 1. Compressive strength and carbonation depth of concrete specimens N. Ø h m P max

R c

Carbonation

mm

mm

kg

kN

MPa 61.5 50.9 55.0 65.2 61.5

mm

P2_A P2_B P3_A P3_B T1_A

94 94 94 94 74

94 94 94 94 74

1.584 1.553 1.619 1.521 0.741

426.5 353.2 381.9 452.3 264.4

0 0 0 0

10mm-internal face 40 mm-external face 18 mm-internal face 40 mm-external face

T2_B

74

74

0.472

317.5

73.8

4. Model and bearing capacity check A 3D finite element model was developed (Figure 4). Mono- dimensional “BEAM” and bi - dimensional “PLATE” elements were used respectively for the longitudinal beams and the slab. Beam elements were linked to plate elements through elastic rigid link that connect the centroid of the beam to the centroid of the slab. Vertical bi-directional supports were introduced to connect the bridge abutment and pier to the ground. For the central supports, two different assumptions were made due to the fact that theoretically the beams should have been simply supported on the piers, while in reality the upper slab was casted creating a continuity between the beams and the piers. A first model (MODEL 01) considers piers as elastic cantilever vertical elements with a hinge located at their top, modelled through translational springs with a stiffness equal to 28.99 kN/mm. A second model (MODEL 02) considers piers as elastic cantilever vertical elements equipped with a flexural continuity to the top, with null rotation; in this case, in addition to the translational springs (stiffness of 115.96 kN/mm), rotational springs was also added, with a stiffness equal to 139553.50 kNm/rad, value obtained by assuming a perfect bending continuity between the pier and the beams, iteratively reduced to obtain a maximum displacement at mid-span equal to the average displacement measured during the acceptance test. The internal forces due to self-weight of the structure were manually computed by means of the simply-supported beam set-up; on the other end, permanent loads and traffic loads were introduced in the model in order to consider the statically undetermined effect.

(a)

(b)

(c)

Figure 4. Finite element model: a) 3D, b) lateral and c) transversal view.