2025 Volume 81 Issue 13 Article ID: 24-13499
A study was conducted to understand the effect of engineering bedrock on the predominant period of surface layer. The results confirmed that even when the natural period Tg derived from eigenvalue analysis is the same, the interaction with engineering bedrock can cause significant changes in the predominant period and ground motion. Additionally, it was clarified that when the natural periods of the first and second modes from eigenvalue analysis are relatively close or when the shear stiffness of the surface layer is relatively large, the influence of engineering bedrock is likely to shorten the predominant period compared to Tg. We proposed a method to easily correct this tendency and confirmed that the proposed method can more appropriately estimate the dominant period of the ground. By using the insights obtained in this study, it is expected to improve the accuracy of estimating the predominant period of ground during earthquakes
