PSI - Issue 70

Surabhi Saxena et al. / Procedia Structural Integrity 70 (2025) 169–174

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bridge with varying height of piers and bond-slip behaviour. The study showed that probability increases with the consideration of bond-slip component and the spectral acceleration. The time history analysis and pushover analysis were also compared. (Zhong et al., 2023) involved continuous beam bridge and different construction methods, with focussing on age factors all along the operation period. The environmental factors, construction methods, varying seismic intensities gave the comprehensive result for the study. (Liu et al., 2023) studied the behavioural impact of vertical ground motion on isolated bearings. 3. Methodology In the current study, analytical method of seismic fragility analysis is conducted. Firstly, pushover analysis is performed and with the help of the findings of such analysis, fragility curves are drawn. Performance point is calculated by intersection of capacity curve and demand curve. Response spectrum function is used to record the response of the structure. The median value for Sa is defined at slight, moderate, extensive and complete damage state by findings of pushover curve and standard deviation is assumed as 0.6. Hazus manual is referred for developing fragility or probability curves. The capacity spectrum method is preferred for calculating the performance point in the pushover curve. The following equation is used for drawing the fragility curve for the selected bridge structure: ( ≥ ) = [ ln( , ) ] (2) Where, Φ =log normal function, Sa=spectral acceleration, Sa,ds=median values for different damage states, β =standard deviation values (0.6). 4. Bridge Modelling In this study, a two-span, simply supported bridge is selected (Banda & Kumar, 2022). Two equal spans of 45m, with a reinforced concrete pier is modelled using SAP2000. A pier of height 5.5m and diameter of 2.5m is selected. Here, the longitudinal reinforcement of 1.15% and transverse reinforcement is used as 12 mm bar at 150mm apart (Fig. 1 & Fig. 2) is provided. The slab has specifications as mentioned, A x =5.9313m 2 , moment of inertia I 33 =4.1968m 4 , I 22 =47.22m 4 (Kim, 2022). For the effect of earthquake, response spectrum function is defined at DBE (design basis earthquake) and MCE (maximum considered earthquake) conditions. M-35 concrete, and Fe-500 are used for bridge modelling.

Fig. 1 Two-span bridge model