Virginia Tech
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Site response data used for deriving ergodicity factors for performing non-ergodic PSHA


Probabilistic seismic hazard analysis (PSHA) is the basis for the development of the National Seismic Hazard Maps (NSHM) produced by the USGS. These maps are adopted by national building codes for the design of structures. For this reason, the hazard maps can have a significant economic impact nationwide and it is important to ensure that the maps reflect the state of the practice in PSHA and properly incorporate all sources of uncertainty that must be accounted for in the hazard analyses. 

   This research has proposed a new framework by which non-ergodic PSHA can be implemented in building codes. Within this framework, the code-based design ground motions are corrected for the ergodicity in site effects using the ‘ergodicity factor’. The ergodicity factor is computed as the ratio of non-ergodic ground motion to the ergodic ground motion at a given hazard level. The factors are computed in hazard space to allow for ready implementation into building codes. The ergodicity factors are postulated as a function of degree of site characterization, which is parameterized using the uncertainty in velocity estimates. The framework was generalized based on multiple soil profiles obtained from the KiK-net database. The generic ergodicity factors based on NEHRP site class and the degree of site characterization is presented.  

 The dataset presented herein is the compilation of the soil velocity profiles obtained from KiK-net database randomized based on Toro randomization model, Fourier Amplitude Spectrum (FAS) of the input motion used for performing site response, results from site response analyses and the ergodicity factors derived in the process. For more details on the research, the users of this dataset are referred to the report " Adrian Rodriguez-Marek and Balakumar Anbazhagan., (2022). A framework for incorporating non-ergodic PSHA in building codes. Final report submitted to United States Geological Survey."


Moving Towards the Use of Single-Station Sigma in National Hazard Maps

United States Geological Survey

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University Libraries, Virginia Tech

Corresponding Author Name

Balakumar Anbazhagan

Corresponding Author E-mail Address

Files/Folders in Dataset and Description

The zip file named "" contains all the data in the form of .csv files organized in the following subfolders. Base profiles - Contains all the velocity profiles obtained from KiK-net database used in the research, organized based on NEHRP site class. Velocity profiles obtained from KiK-net database (in .csv format) Randomized profiles - Each base profile is randomized 100 times using Toro randomization model. The files are presented in .csv format. Each base profile in 'Base profiles' folder is randomized based on Toro (1995) model. 100 randomized profiles were generated for each profile for varying degrees of site characterization (uncertainty in Vs). Input motion - Contains the Fourier Amplitude Spectrum (FAS) that was used as the input motion for performing site response analyses. Fourier Amplitude Spectrum of the input motion used for performing site response analyses (in .csv format) Site response results - Contains the mean amplification and uncertainty obtained from site response analyses. Results from Site response analyses. The folder contains mean amplification along with uncertainty for each soil profile. (in .csv format) Ergodicity factors - Contains the ergodicity factors for each site class. Ergodicity factors derived in this research for each NEHRP site class (in .csv format) README.rtf - Description of the files in the dataset.

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