Seismic zonation and default suites of ground-motion records for time-history analysis in the South Island of New Zealand

Christianos Burlotos,Nicholas Brooke,Kevin Walsh,Tatiana Goded,Graeme Mcverry,Jason Ingham

doi:10.5459/bnzsee.55.1.25-42

Abstract

The rise of performance-based earthquake engineering, in combination with the complexity associated with selecting records for time-history analysis, demonstrates an expressed need for localized default suites of ground motion records for structural designers to use in the absence of site-specific studies. In the current research investigation, deaggregations of probabilistic seismic hazard models (National Seismic Hazard Model, Canterbury Seismic Hazard Model, and Kaikōura Seismic Hazard Model) and the location-specific seismological characteristics of expected ground motions were used to define eight seismic hazard zonations and accompanying suite profiles for the South Island of New Zealand to satisfy the requirements of the New Zealand structural design standard NZS1170.5 for response-history analyses. Specific records, including 21 from the recent Kaikōura, Darfield, and Christchurch earthquakes, were then selected from publicly-available databases and presented as default suites for use in time-history analyses in the absence of site-specific studies. This investigation encompasses seismic hazards corresponding to 500-year return periods, site classes C (shallow soils) and D (deep soils), and buildings with fundamental periods between 0.4 and 2.0 seconds.

Highlights

In order to accurately simulate the resilience to earthquakes of buildings and infrastructure facilities in a community, engineers and other researchers must model the performance of both building structural and non-structural components [1]
The process for selecting such records often requires the consultation of seismologists, because it is beyond the capacity of most designers to utilize the probabilistic seismic hazard models used to define the sitespecific hazard spectra and to identify the ground motion sources which contribute to these spectra
The two locations processed in this zone, Otira and Springs Junction, correspond to critical points along main roads on the South Island. 50% of the disaggregated seismicity plotted for Springs Junction originates from the Alpine (Kaniere-Tophouse) fault, whereas the Kelly fault contributes 58% of the disaggregated seismicity for Otira

Summary

Introduction

In order to accurately simulate the resilience to earthquakes of buildings and infrastructure facilities in a community, engineers and other researchers must model the performance of both building structural and non-structural components [1]. In order to fully utilize the benefits of rapidly improving performancebased design methodologies [2-5], the modelling of both demands and building components is best accomplished using nonlinear time-history analysis (NLTHA) with appropriately selected ground-motion earthquake records. To assist engineers utilizing NLTHA in New Zealand, criteria for the selection and scaling of ground-motion records is defined in NZS 1170.5:2016 [6,7], referred to as “the Standard”. The process for selecting such records often requires the consultation of seismologists, because it is beyond the capacity of most designers to utilize the probabilistic seismic hazard models used to define the sitespecific hazard spectra and to identify the ground motion sources which contribute to these spectra. The goal of the current study was to recommend a suite of NZS1170compliant ground-motion records for engineers conducting provisional design and assessment of buildings in the South

Objectives

Methods

Findings

Conclusion