Open-File Report 2015–1116

NGA-West2 GMPE Average Site Coefficients for Use in Earthquake-Resistant Design

By Roger D. Borcherdt

Abstract

Site coefficients corresponding to those in tables 11.4–1 and 11.4–2 of Minimum Design Loads for Buildings and Other Structures published by the American Society of Civil Engineers (Standard ASCE/SEI 7-10) are derived from four of the Next Generation Attenuation West2 (NGA-W2) Ground-Motion Prediction Equations (GMPEs). The resulting coefficients are compared with those derived by other researchers and those derived from the NGA-West1 database. The derivation of the NGA-W2 average site coefficients provides a simple procedure to update site coefficients with each update in the Maximum Considered Earthquake Response MCER maps. The simple procedure yields average site coefficients consistent with those derived for site-specific design purposes. The NGA-W2 GMPEs provide simple scale factors to reduce conservatism in current simplified design procedures.

First posted June 16, 2015, updated June 25, 2015

Report PDF (346 kB)

This publication is online only

For additional information, contact:
Earthquake Science Center—Menlo Park, Calif. Office
U.S. Geological Survey
345 Middlefield Road, MS 977
Menlo Park, CA 94025
http://earthquake.usgs.gov/

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Suggested citation:

Borcherdt, R.D., 2015, NGA-West2 GMPE average site coefficients for use in earthquake-resistant design (ver. 1.1, June 25, 2015): U.S. Geological Survey Open-File Report 2015–1116, 27 p., https://dx.doi.org/10.3133/ofr20151116.

ISSN 2331-1258 (online)

Acknowledgments

Contents

NGA-West2 GMPE Average Site Coefficients for Use in Earthquake-Resistant Design

Abstract

Introduction

NGA-West2 Site Coefficients

NGA-W2 Amplification as a Function of Period

Comparison of NGA-W2 and NGA-W1 Amplification Factors with NEHRP Coefficients

NGA-W2 Scaling Factors to Reduce Conservatism in Design Spectra and to Scale Site Amplification Coefficients to Other Reference Site Conditions

Implications of NGA-W2 for ASCE 7-10 (NEHRP) Site Coefficients

Comparison of NGA-W2 Coefficients with Those Proposed for ASCE 7-16

Conclusions

References

Figures (13)

Tables (8)

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