PSI - Issue 52

Govardhan Polepally et al. / Procedia Structural Integrity 52 (2024) 487–505 Govardhan Polepally/ Structural Integrity Procedia 00 (2019) 000 – 000

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which are primarily defined by bending and torsion movements in the vertical direction. The grade of concrete employed in the numerical model are given in Table 8. A detailed site investigation has been carried out for the geometrical specifications of the bridge which are shown in Fig. 3 to 7. Boundary conditions considered for the numerical model are taken as nearest to the actual existing bridge at the site. Based on the visual inspection the base of the bridge is assumed to be fixed and two edges are assumed to be frictionless as they are expansion joints as shown in table 3. As mentioned earlier, the material properties considered for the bridge were obtained from the concrete core test. As a factor of safety 1.25 is applied to the obtained compressive strength of the concrete core and the same has been applied to the numerical model. This is also supported by UPV test values as shown in table 4.

Table 3. Material properties considered for the bridge Member

Boundary Condition

Bottom

Fixed

Left Side Abutment

Frictionless

Right Side Abutment

Frictionless

Table 4. Material properties considered for the bridge Bridge No Average Compressive strength of Concrete (MPa)

Grade of Concrete considered for FEM Analysis (MPa)

Bridge 1 Bridge 2 Bridge 3 Bridge 4 Bridge 5

39.90 41.72 37.56 33.09 28.19

40 40 35 30 25

Three load cases have been considered for this study, which depicts all possibilities of maximum deformation and stresses. Every load case consists of the following load combination: i. Gravity (Self-weight), ii. UDL due to ballast (considered thickness – 400 mm, density 1600 kg/m 3 ), iii. Live loads (9.4 MT and 25 MT). As per the Code of Practice for Plain, Reinforced & Prestressed Concrete for General Bridge Construction IRS Concrete Bridge Code table 12, we consider load Combinations and Load factors as follows: a) The dead weight of concrete =1.25 Superimposed dead load = 2.0 b) Live load = 1.75 (Live load + Dynamic effect).

Fig. 11. Finite Element Model of Bridge No. 1 (a) 3D view; (b) Cross-section .