Investigating the influence of topographic irregularities and two-dimensional effects on surface ground motion intensity with one- and two-dimensional analyses

Abstract

In this work, the surface ground motion that occurs during an earthquake in ground sections having different topographic forms has been examined with one and two dynamic site response analyses. One-dimensional analyses were undertaken using the Equivalent-Linear Earthquake Response Analysis (EERA) program based on the equivalent linear analysis principle and the Deepsoil program which is able to make both equivalent linear and nonlinear analyses and two-dimensional analyses using the Plaxis 8.2 software. The viscous damping parameters used in the dynamic site response analyses undertaken with the Plaxis 8.2 software were obtained using the DeepSoil program. In the dynamic site response analyses, the synthetic acceleration over a 475year return period representing the earthquakes in Istanbul was used as the basis of the bedrock ground motion. The peak ground acceleration obtained different depths of soils and acceleration spectrum values have been compared. The surface topography and layer boundaries in the 5-5 cross section which cuts across the study area west to east were selected in order to examine the effect of the land topography and layer boundaries on the analysis results, and were flattened and compared with the actual status. The analysis results showed that the characteristics of the surface ground motion change in relation to the varying local soil conditions and land topography.Published by Copernicus Publications on behalf of the European Geosciences Union. Syst. Sci., 14, 1773-1788, 2014 www.nat-hazards-earth-syst-sci.net/14/1773/2014/ G. Ç.İnce and L. Yılmazoglu: Investigating the influence of topographic irregularities Nat. Hazards EarthConsidering the results, it is observed that the surface topography has an influence on and changes the acceleration value. Moreover, when the field topography becomes flat, the acceleration values can be said to increase in the one and two-dimensional analyses.

An Investigation of Local Site Effects Using Linear and Nonlinear analysis and Comparison Between Them

“…Program EERA was developed in FORTRAN90 from this basic code to take full advantage of the dynamic array dimensioning and matrix operations (Bardet et al, 2000). EERA's input and output are integrated with the spreadsheet program Excel [5][6][7].…”