PSI - Issue 70

Aman Kumar et al. / Procedia Structural Integrity 70 (2025) 255–262

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the fragility analysis. The fragility analysis provides the fragility curve of the building in slight, moderate, extreme, and collapse damage states. Fragility curves are generated by using the probabilistic model as per the Hazus manual 2.1 (2003). The probability of damage to the building can be estimated by intersecting the building's fragility curve with the spectral displacement demand corresponding to the seismic response of the building to a particular earthquake. Yield and Ultimate displacement are the primary inputs to estimate the damage probability of the building (Barbet et al., 2008).

Fig. 2. (i) Flow chart of Methodology and (ii) Matched Response spectrum compatible to the MCE response spectrum

4. Results and discussion 4.1. Soil amplification

Soil amplification is a phenomenon where the amplitude of seismic ground motion significantly increases as it propagates through specific soil layers. The amplified seismic waves result in increased seismic demand or roof displacement in structures. To understand this effect, three near-field ground motion GM 1(Cape Mendocino, Petrolia_PET000), GM 2 (Coyote Lake, Gilroy Array #6_G06230), GM 3(Imperial valley, Brawley Airport-BRA225) are considered in the present study from the PEER ground motion database and made compatible with the IS 1893:2016 maximum considered earthquake (MCE) response spectrum as shown in Figure 2 (ii). Soil profile has been modelled in DEEPSOIL software by using the soil characteristics from the borehole data taken from Sargin et al. (2017), such as soil stratification, SPT-N values, shear wave velocity, and layer thickness, as shown in Figure 3a. DEEPSOIL software is used for one-dimensional seismic site response analysis to evaluate soil layer influence on the ground motion during seismic activity. Various soils have unit weights ranging from 19.2-24 kN/m 3 , shear wave velocity ranging from 150-900 m/sec, and minimum damping of soil ranging from 2-5%. Blue lines represent the modified ground motions applied at the bedrock level, and the orange line represents the amplified surface-level ground motion, as presented in Figure 3b. It has been observed that the Peak ground acceleration value has increased by 0.84 g (0.47 g to 1.27 g) in GM 1, 0.75 g (0.46 g to 1.21 g) in GM 2, and 0.8 g (0.45 g to 1.25 g) in GM 3. Similarly, the Peak spectral acceleration (PSA) value increased by 3.15 g (1.06 to 4.21 g) in GM 1, 3.58 g (0.98 to 4.56 g) in GM 2, and 2.98 g (1.08 to 4.06 g) in GM 3. The results show that each ground motion amplifies at the surface level significantly, but the amplification varies for each ground motion differently. The soil amplification