Bulletin of the New Zealand Society for Earthquake Engineering 2023-12-11T14:31:56+13:00 Rajesh Dhakal Open Journal Systems <p>Bulletin of the New Zealand Society for Earthquake Engineering</p> Infrastructure planning emergency levels of service for the Wellington region, Aotearoa New Zealand – An operationalised framework 2023-12-11T14:31:24+13:00 Richard Mowll Julia Becker Liam Wotherspoon Carol Stewart David Johnston Daniel Neely <p class="Summary">‘Planning Emergency Levels of Service’ (PELOS) are goals for the delivery of infrastructure services following a major hazard event, such as an earthquake or flood. This paper presents an operationalised PELOS framework for the Wellington region based on interviews with emergency and critical infrastructure managers and discusses important changes from the preliminary to the operationalised framework. A shared understanding of these PELOS will help Wellington region infrastructure providers, emergency management professionals and the potentially impacted communities plan for major events. PELOS for the energy, telecommunications, transport, and water sectors have been developed, and high-level interdependencies considered. The PELOS framework can be updated for other regions, by the critical infrastructure entities and emergency managers, using locally relevant hazard scenarios. In turn, this approach can inform the end-users (communities) of the goals of the critical infrastructure providers following a major hazard event.</p> 2023-12-09T00:00:00+13:00 Copyright (c) 2023 Richard Mowll, Julia S. Becker, L. M. Wotherspoon , C. Stewart, David Johnston, Dan P. Neely Earthquake design loads for retaining walls 2023-12-11T14:31:56+13:00 John Wood <p>Free-standing retaining walls are usually designed for earthquake loads assuming cohesionless backfill soil and using the Mononobe-Okabe method. This simple design approach has led to satisfactory performance and is supported by laboratory testing and analytical studies. For major wall structures there are a number of refinements to the method that should be considered. In the paper methods of assessing the influence on the earthquake loads of the flexibility of the wall, soil cohesion and ground water in the backfill are presented. Equations for predicting failure plane angles to allow a better assessment of the soil properties within the failure wedge are included. Procedures for estimating the outward displacement and the influence of passive resistance and wall geometry on the sliding resistance are discussed. Design charts are presented which allow the magnitude of these refinements to be rapidly assessed.</p> 2023-12-09T00:00:00+13:00 Copyright (c) 2023 John Wood Seismic fragility of reinforced concrete buildings with hollow-core flooring systems 2023-12-11T14:31:08+13:00 Tom Francis Eyitayo Opabola Timothy Sullivan Kenneth Elwood Cameron Belliss <p class="Summary">Hollow-core flooring systems were damaged in Wellington buildings during the 2016 Kaikoura earthquake (7.8 M<sub>w</sub>) and have been shown to be susceptible to undesirable failure mechanisms (loss of seating, negative moment, and positive moment failure modes) at low drift demands. These undesirable damage mechanisms have also been observed in sub-assembly and super-assembly laboratory testing of hollow-core flooring systems and the test data obtained has enhanced the state-of-the-art knowledge of the probable seismic behaviour of hollow-core floor units. In this study, using currently available sub-assembly test data, fragility functions are defined for hollow-core flooring systems. Furthermore, the proposed fragility functions are combined with fragility information derived from nonlinear dynamic analyses for two eight-storey bare-frame reinforced concrete (RC) buildings designed based on New Zealand standards. This study shows that, in comparison with RC buildings with flooring systems that are not susceptible to gravity load failures, RC buildings with vulnerable hollow-core floors have a significantly higher likelihood of exceeding the collapse prevention limit state, as defined in this study.</p> 2023-12-09T00:00:00+13:00 Copyright (c) 2023 Tom Francis, Eyitayo Opabola, Timothy Sullivan, Kenneth Elwood, Cameron Belliss Evaluation of the Inter-frequency Correlation of New Zealand CyberShake Crustal Earthquake Simulations 2023-12-11T14:31:40+13:00 Jeff Bayless Scott Condon <p>The inter-frequency correlation of ground-motion residuals is related to the width of peaks and troughs in the ground-motion spectra (either response spectra or Fourier amplitude spectra; FAS) and is therefore an essential component of ground-motion simulations for representing the variability of structural response. As such, this component of the simulations requires evaluation and validation when the intended application is seismic fragility and seismic risk. This article evaluates the CyberShake NZ [1] crustal earthquake ground-motion simulations for their inter-frequency correlation, including comparisons with an empirical model developed from a global catalogue of shallow crustal earthquakes in active tectonic regions, and with results from similar simulations (SCEC CyberShake; [2]). Compared with the empirical model, the CyberShake NZ simulations have a satisfactory level of total inter-frequency correlation between the frequencies 0.1 – 0.25 Hz. At frequencies above 0.25 Hz, the simulations have lower (statistically significant at 95% confidence level) total inter-frequency correlation than the empirical model and therefore require calibration. To calibrate the total correlation, it is useful to focus on the correlation of the residual components. The between-event residual correlations, physically related to source effects (e.g., stress drop) which drive ground motions over a broad frequency range, are low at frequencies greater than about 0.25 Hz. Modifications to the cross-correlation between source parameters in the kinematic rupture generator can improve the inter-frequency correlations in this range [3]. The between-site residual correlations, which represents the correlation between frequencies of the systematic site amplification deviations, are larger (statistically significant at 95% confidence level) than the empirical model for frequencies less than about 0.5 Hz. We postulate that this relates to the relative simplicity of site amplification methods in the simulations, which feature less variability than the amplification observed in the data. Additional insight would be gained from future evaluations accounting for repeatable path and basin effects, using simulations with refined or alternative seismic velocity models, and using simulations with a higher crossover frequency to deterministic methods (e.g., 1 Hz or higher).</p> 2023-12-09T00:00:00+13:00 Copyright (c) 2023 Jeff Bayless, Scott Condon