A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Site Response in NEHRP Provisions and NGA Models
Site factors are used to modify ground motions from a reference rock site condition to reflect the influence of geologic conditions at the site of interest. Site factors typically have a small-strain (linear) site amplification that captures impedance and resonance effects coupled with nonlinear components. Site factors in current NEHRP Provisions are empirically-derived at relatively small ground motion levels and feature simulation-based nonlinearity. We show that NEHRP factors have discrepancies with respect to the site terms in the Next Generation Attenuation (NGA) ground motion prediction equations, both in the linear site amplification (especially for Classes B, C, D, and E) and the degree of nonlinearity (Classes C and D). The misfits are towards larger linear site factors and stronger nonlinearity in the NEHRP factors. The differences in linear site factors result largely from their normalization to a reference average shear wave velocity in the upper 30 m of about 1050 m/s, whereas the reference velocity for current application is 760 m/s. We show that the levels of nonlinearity in the NEHRP factors are generally stronger than recent simulation-based models as well as empirically-based models.
Site Response in NEHRP Provisions and NGA Models
Site factors are used to modify ground motions from a reference rock site condition to reflect the influence of geologic conditions at the site of interest. Site factors typically have a small-strain (linear) site amplification that captures impedance and resonance effects coupled with nonlinear components. Site factors in current NEHRP Provisions are empirically-derived at relatively small ground motion levels and feature simulation-based nonlinearity. We show that NEHRP factors have discrepancies with respect to the site terms in the Next Generation Attenuation (NGA) ground motion prediction equations, both in the linear site amplification (especially for Classes B, C, D, and E) and the degree of nonlinearity (Classes C and D). The misfits are towards larger linear site factors and stronger nonlinearity in the NEHRP factors. The differences in linear site factors result largely from their normalization to a reference average shear wave velocity in the upper 30 m of about 1050 m/s, whereas the reference velocity for current application is 760 m/s. We show that the levels of nonlinearity in the NEHRP factors are generally stronger than recent simulation-based models as well as empirically-based models.
Site Response in NEHRP Provisions and NGA Models
Seyhan, Emel (author) / Stewart, Jonathan P. (author)
GeoCongress 2012 ; 2012 ; Oakland, California, United States
2012-05-29
Conference paper
Electronic Resource
English
Site Response in NEHRP Provisions and NGA Models
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