PSI - Issue 70

Jaiyash Jaiswal et al. / Procedia Structural Integrity 70 (2025) 596–603

598

and delta-shaped pylons performed best under seismic loading. Additionally, changes in deck width for a constant main span had minimal effect on normalized shear force. However, limited studies are available on effect of cable stiffness with variation in its modulus of elasticity on the responses of cable stayed bridge including girder and tower deflection and bending moment. 1.2. Tables In the following tables, the properties of materials which are used for modelling the cabled stayed bridges are listed.

Table 1. Properties of materials

Material properties

Cross-section properties

Density (kN/m 3 )

Poisson ’s ratio

Material

Elasticity (N/mm 2 )

Area (m 2 )

I

XX (m

4 )

I

YY (m

4 )

I

ZZ (m

4 )

Cable

1.96E+08

77.09

0.3

5.20E-03

0

0

0

Girder

2.00E+08

77.09

0.3

3.09E-01

7.00E-03

1.58E-01

4.76E+00

Pylon (Concrete) Cross beam (Girder) CrossBeam (Tower)

2.78E+07

23.56

0.2

9.2E+00

1.95E+01

2.56E+01

8.12E+00

1.96E+08

77.09

0.3

4.99E-02

3.10E-03

4.47E-02

1.33E-01

2.78E+07

23.56

0.2

7.20E+00

1.58E+01

1.45E+01

7.99E+00

2. Methodology To study the effect of cable stiffness on cable stayed bridges two variables viz., which is Modulus of elasticity and cross-sectional area of the cable are considered. Three different cable material properties are chosen and their modulus of elasticity are as follows 1.65×10 8 N/mm 2 , 1.96×10 8 N/mm 2 and 2.1×10 8 N/mm 2 . And for a specific modulus of elasticity i.e. 1.96×10 8 N/mm 2 cable area is increased by 5 -20%. For all these properties of the cables, the structure has been modelled in MIDAS CIVIL software. The cable stayed bridge selected for the analysis is a three-span bridge (4-lane) of total length 420m, where side spans of length 100 m and main span of length 220 m are provided. Cable is modelled as truss element. Elastic spring used as support representing soil in term of stiffness. Moving load analysis is done as per IRC 6:2017. After modelling the bridge, unknown load factor optimization in MIDAS CIVIL is used which calculates the load factors in order to satisfy specific constraints like displacement or bending moment defined for a system. Based on these constraints prestressing force is applied in the cable. In the other study, the modulus of elasticity of the cable is altered, keeping area constant. The results of the study are presented in the graphical form. The model of the bridge (longitudinal profile) and different types of cable are presented in Fig.1. 3. Validation For the data validation an example problem is taken from Midas academy tutorial and modelled in software. Results are compared and are within acceptable limit. Table 2. Validation of work Parameters Actual values Values from model Deflection of Girder 24.5 mm 24.49 mm Maximum positive Moment 8961 kN-m 8962 kN-m Maximum negative Moment 4404 kN-m 4403 kN-m