PSI - Issue 78

Atilla Ansal et al. / Procedia Structural Integrity 78 (2026) 2133–2140

2138

was average spectral accelerations calculated by site response analysis and empirical amplification factor calculated based on V s30 (Borcherdt, 1994). Various microzonation parameters were proposed by Brax et al. (2018); Mancini et al. (2014); Pagliaroli et al. (2014); Strollo et al. (2012); Lanzo et al (2011); Grasso and Maugeri (2009); Singh et al (2007); Papadimitriou et al. (2008); Alvarez et al. (2004); Pergalani et al. (2020) and others. However, the damages in recent earthquakes have given better correlations with the Housner Intensity, HI and Cumulative Absolute Velocity, CAV (Cabanas, et al, 1997; Campbell & Bozorgnia, 2012; Elenas, 2000; Elenas & Meskouris, 2001; Miyakoshi & Hayashi, 2000; Perrault & Gueguen, 2015, Riddel, 2007, Wu et al., 2012) The above-summarized microzonation procedure was applied to the city of Bolu, which experienced 1999 Düzce earthquake. The initial microzonation project, supported by the Bolu Municipality, was conducted by the author and his colleagues (Ansal et al., 2007a). Recently, a new microzonation study was conducted (Ansal, 2025) based on the latest procedures developed by the author and his colleagues (Tonuk & Ansal, 2022, Tonuk et.al., 2013). Based on 250 soil explorations that were available, 214 cells with specifically assigned soil profiles were identified to conduct site response analysis. Site response analyses were conducted using the modified version of Shake91 (Ansal, et al. 2007b, Sugito, et. al. (1994), Idriss & Sun, 1992, Schabel, et al., 1972). Generating 100 Monte Carlo simulations for all soil profiles with respect to layer thickness and shear wave velocity assuming normal distribution with 25% variability, 21400 site response analyses were conducted for 20 acceleration histories scaled to the probabilistic uniform acceleration hazard spectrum on the engineering bedrock. Based on the new site response analyses results, a new microzonation maps are developed for the recently suggested parameters for probabilistic Cumulative Average Velocity and Housner Intensity (Ansal, 2025). A comparison of this microzonation map is shown with respect to the observed damage distribution during the 1999 Düzce earthquake in the Bolu city in Figure (Erdik et al., 2007).

Figure 7. The comparison of microzonation with the observed damage distribution for collapsed buildings and probabilistic CAV-HI microzonation map The comparison between the microzonation map and observed damage distribution (Figure Figure 7) indicates to a limited extent that cells estimated to have high and medium shaking intensity coincide with higher number of collapsed buildings. Even though structural damages are mostly controlled by structural properties, the effects of site conditions may play an important role, if site conditions are not considered during the design of buildings and foundations. This happens to be general practice in the construction industry in Türkiye.