https://bulletin.nzsee.org.nz/index.php/bnzsee/issue/feed Bulletin of the New Zealand Society for Earthquake Engineering 2022-03-01T23:39:38+13:00 Rajesh Dhakal rajesh.dhakal@canterbury.ac.nz Open Journal Systems <p>Bulletin of the New Zealand Society for Earthquake Engineering</p> https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1595 Re-evaluation of New Zealand seismic hazard for geotechnical assessment and design 2022-03-01T14:30:38+13:00 Misko Cubrinonski misko.cubrinovski@canterbury.ac.nz Brendon Bradley brendon.bradley@canterbury.ac.nz Frederick Wentz rwentz@wp-geo.co.nz Ananth Balachandra ananth.balachandra@tonkintaylor.co.nz <p>This paper scrutinises the seismic hazard of New Zealand (NZ) from a geotechnical engineering perspective. The two codified versions of the seismic hazard in NZS1170.5 (structural loading standard) and NZTA Bridge Manual (NZTA-BM) are shown to yield consistently different peak ground acceleration (<em>PGA</em>) hazards throughout NZ. Results from site-specific PSHA for 24 locations in NZ are used to examine key hazard characteristics, including earthquake magnitude and the effects of site conditions (classes) on the <em>PGA</em> hazard. The comparative evaluations show that for most of the locations considered, NZS1170.5 and NZTA-BM overestimate the <em>PGA</em> hazard. However, NZS1170.5, and NZTA-BM in particular, significantly underestimate the <em>PGA</em> hazard for locations that are at a short source-to-site distance from the Hikurangi Subduction Zone (HSZ), and for which HSZ significantly contributes to their hazard. Using the results from this study, an interim <em>PGA</em> hazard is recommended for geotechnical assessment and design in support of the NZ guidelines for geotechnical earthquake engineering practice. The recommended interim <em>PGA</em> hazard is applicable to all site classes without any modification or use of site amplification factors.</p> 2022-03-01T00:00:00+13:00 Copyright (c) 2022 https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1596 Probabilistic seismic hazard analysis of peak ground acceleration for major regional New Zealand locations 2022-03-01T17:03:24+13:00 Brendon Bradley brendon.bradley@canterbury.ac.nz Misko Cubrinovski misko.cubrinovski@canterbury.ac.nz Frederick Wentz rwentz@wp-geo.co.nz <p>This paper presents site-specific probabilistic seismic hazard analysis (PSHA) results at 24 locations throughout New Zealand (NZ). Specifically, peak ground acceleration (PGA) hazard curves for two generic soft soil conditions are considered. For specific return periods of interest, seismic hazard disaggregation is used to obtain the percentage contributions of various seismic sources to the hazard, including metrics such as mean earthquake magnitude used for simplified geotechnical calculations. The seismic hazard analyses utilise concensus models for seismic source and ground-motion characterisation, including consideration of alternative ground-motion models. The analyses therefore represent an appreciable improvement relative to the science that underpin current loading standards [e.g., 1,2]. Consequently, we advocate the use of these results as a scientific basis for potential revisions to standards and guidance documents that characterise seismic hazard via PGA.</p> 2022-03-01T00:00:00+13:00 Copyright (c) 2022 https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1475 Seismic zonation and default suites of ground-motion records for time-history analysis in the South Island of New Zealand 2021-04-23T14:39:30+12:00 Christianos Burlotos cburloto@nd.edu Kevin Walsh kwalsh8@nd.edu Tatiana Goded T.Goded@gns.cri.nz Graeme McVerry graememcv@gmail.com Nicholas Brooke nic@compusoftengineering.com Jason Ingham j.ingham@auckland.ac.nz <p class="Summary"><span lang="EN-NZ">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.</span></p> 2022-03-01T00:00:00+13:00 Copyright (c) 2022 Christianos Burlotos, Kevin Walsh, Tatiana Goded, Graeme McVerry, Nicholas Brooke, Jason Ingham https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1507 Shear wave velocities of prominent geologic formations in the Nelson-Tasman region 2021-11-21T21:48:50+13:00 Liam Wotherspoon l.wotherspoon@auckland.ac.nz Rebecca Ryder rebeccajmmcmahon@gmail.com Andrew Stolte andrew.stolte@canterbury.ac.nz <p>This paper presents the development of representative shear wave velocity profiles for the prominent geologic formations in the Nelson-Tasman region of New Zealand. Shear wave velocity (V<sub>S</sub>) profiles to depths of up to 100 m were developed at over 50 sites using a combination of active source and passive source surface wave testing. Using this data and regional geologic information, V<sub>S</sub>-depth functions were developed for six of the prominent geologic formations. Comparison with existing V<sub>S</sub>-depth functions from New Zealand and international studies highlighted the significantly higher shear wave velocities of the deposits in this region. V<sub>S</sub> exceeded 750 m/s for the Moutere Gravels and Port Hills Gravels at relatively shallow depths, representative of rock deposits. However, while the Port Hills Gravels transition to a conglomerate rock below depths of 30 m or less, the Moutere Gravel formation is an uncemented clay-bound gravel. The young gravel and sand deposits have V<sub>S</sub> higher than those from other regions. As the region is thought to have undergone cycles of geologic uplift, the resulting over-consolidation of these deposits could explain the high V<sub>S</sub>. Horizontal-to-vertical spectral ratio testing was not able to characterise the fundamental site period across the region, likely due to the weak impedance contrast that would exist at the gravel-rock interface at depth. These outcomes highlight the importance of regional geotechnical and geophysical characterisation to constrain the salient features that control potential seismic site amplification and site classification.</p> 2022-03-01T00:00:00+13:00 Copyright (c) 2022 Liam Wotherspoon, Rebecca Ryder, Andrew C. Stolte https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1567 Industry impact of QuakeCoRE Flagship Programme 4 2021-11-21T21:50:06+13:00 Matthew Fox mat.j.fox@gmail.com Jared Keen jared.keen@beca.com <p class="Summary">QuakeCoRE is one of 10 Centres of Research Excellence funded by the New Zealand Tertiary Education Commission. With a focus on earthquake resilience of communities and societies, it has played a major role in addressing needs identified following the Christchurch Earthquake and other major events over the last decade. QuakeCoRE comprises a number of Flagship Programmes, including Flagship 4, which is entitled “Next-generation infrastructure: Low-damage and repairable solutions.” This paper aims to support turning research into practice by identifying the key areas of Flagship 4 that are likely to have an impact on the industry. Five key areas of impact were identified, based on a review of the published research, engagement with Flagship 4 leadership and the authors’ experience in the industry. For each area identified, summaries of the major research outcomes are provided, along with views as to how these can support the engineering practice.</p> 2022-03-01T00:00:00+13:00 Copyright (c) 2022 Matthew Fox, Jared Keen