16 results for Bradley, Brendon, Conference poster

  • The South Island Velocity Model (SIVM) - Version 1: Computational implementation and Integration within the Unified Community Velocity Model (UCVM) framework

    Thomson, Ethan; Bradley, Brendon; Lee, Robin L. (2016)

    Conference poster
    University of Canterbury Library

    This poster presents the computational implementation of the South Island Velocity Model (SIVM) Version 1, constructed for use in physics-based ground motion simulation. A planned integration of the SIVM within the Unified Community Velocity Model (UCVM) framework is presented which will allow researchers to generate velocity models for use in ground motion simulations using standardized approaches. The SIVM allows any fault rupture located in the South Island to be simulated. Figure 4 illustrates the results of ground motion simulations for three rupture scenarios of the Alpine Fault.

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  • Simulation of site amplification effects at Heathcote Valley during the 2010-2011 Canterbury earthquakes

    Jeong, Seokho; Bradley, Brendon (2016)

    Conference poster
    University of Canterbury Library

    Heathcote Valley school strong motion station (HVSC) consistently recorded ground motions with higher intensities than nearby stations during the 2010-2011 Canterbury earthquakes. For example, as shown in Figure 1, for the 22 February 2011 Christchurch earthquake, peak ground acceleration at HVSC reached 1.4 g (horizontal) and 2 g (vertical), the largest ever recorded in New Zealand. Strong amplification of ground motions is expected at Heathcote Valley due to: 1) the high impedance contrast at the soil-rock interface, and 2) the interference of incident and surface waves within the valley. However, both conventional empirical ground motion prediction equations (GMPE) and the physics-based large scale ground motions simulations (with empirical site response) are ineffective in predicting such amplification due to their respective inherent limitations.

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  • Hybrid Broadband Ground Motion Simulations of Porters Pass Earthquakes

    Nazer, M. Ahsan; Bradley, Brendon; Razafindrakoto, Hoby (2016)

    Conference poster
    University of Canterbury Library

    We present ground motion simulations of the Porters Pass (PP) fault in the Canterbury region of New Zealand; a major active source near Christchurch city. The active segment of the PP fault has an inferred length of 82 km and a mostly strike-slip sense of movement. The PP fault slip makes up approximately 10% of the total 37 mm/yr margin-parallel plate motion and also comprises a significant proportion of the total strain budget in regional tectonics. Given that the closest segment of the fault is less than 45 km from Christchurch city, the PP fault is crucial for accurate earthquake hazard assessment for this major population centre. We have employed the hybrid simulation methodology of Graves and Pitarka (2010, 2015), which combines low (f1 Hz) frequencies into a broadband spectrum. We have used validations from three moderate magnitude events (??4.6 Sept 04, 2010; ??4.6 Nov 06, 2010; ??4.9 Apr 29, 2011) to build confidence for the ?? > 7 PP simulations. Thus far, our simulations include multiple rupture scenarios which test the impacts of hypocentre location and the finite-fault stochastic rupture representation of the source itself. In particular, we have identified the need to use location-specific 1D ??/?? models for the high frequency part of the simulations to better match observations.

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  • Guidance on the utilisation of ground motion simulations in engineering practice

    Bradley, Brendon; Pettinga, Didier; Baker, Jack W. (2016)

    Conference poster
    University of Canterbury Library

    This poster presents ongoing work to develop guidance on the utilization of ground motion simulations for engineering practice. The two central ideas in the guidance are, firstly, the indended use of the simulations: For hazard analysis and/or providing ground motion records for use in seismic response analysis of engineered structures. Secondly, a heriarichal validation matrix to systematically develop predictive confidence in the simulated motions in generic regions through to site-specific applications. There are two principal manners in which simulated ground motions can be utilized: In determination of the seismic hazard: Most rigorously, the seismic hazard would be directly obtained from ground motion simulation-based PSHA (e.g. CyberShake). Alternatively, simulations can inform the functional form in empirical ground motion models. Ground motions for seismic response analysis: Simulated ground motions can supplement existing empirical (as-recorded) ground motion databases (e.g. for large Mwsmall Rrup cases which are poorly represented). Target amplitudes can be defined from traditional or simulation-based PSHA, or a code-based response spectrum.

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  • OpenSLAT: Software Tools for Seismic Loss Analysis

    Gauland, Michael; Moghaddasi, Masoud; Bradley, Brendon (2016)

    Conference poster
    University of Canterbury Library

    OpenSLAT is an open-source, object-oriented and extensible extension of the Seismic Loss Assessment Tool (SLAT; Bradley; 2009). Like its predecessor, OpenSLAT is a set of software components based around the Performance-based Earthquake Engineering (PBEE) framework from the Paci c Earthquake Engineering Research Center (PEER). OpenSLAT is written in C++ and Python, and allows users to create projects as C++ or Python programs, or as commands in its own language. OpenSLAT is intended for use by both researchers and practising engineers, and is released under an open-source license to encourage contributions from the user community.

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  • A Robust Framework for Benchmarking Seismic Performance of Modern New Zealand Code-Conforming Buildings

    Moghaddasi, Masoud; Bradley, Brendon; Preston, G. (2016)

    Conference poster
    University of Canterbury Library

    This poster presents an overview of the project defined to develop a robust framework for benchmarking the seismic performance of modern New Zealand core-conforming buildings including conventional and low-damage concrete and steel structures. The immediate need for this project has been seen through UC Quake Centre's engagement with engineering practitioners. This framework follows the methodology introduced by Pacific Earthquake Engineering Research (PEER) centre for performance-based earthquake engineering. PEER's Framework was primary developed to improve the decision-making procedures regarding the seismic performance of the buildings using some measurable decision variables. It provides a comprehensive understanding of risk exposures related to structural and non-structural components and building contents and facilitate decision making for territorial authorities, property owners, commercial tenants, engineers and contractors.

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  • QuakeCoRE Ground Motion Simulation Computational Workflow

    Bae, Sung Eun; Polak, Viktor; Clare, Richard; Bradley, Brendon; Razakindrakoto, Hoby (2016)

    Conference poster
    University of Canterbury Library

    Significant portions of QuakeCoRE research require large-scale computationally-intensive numerical ground motion (GM) simulations. The amount of data and complexity of computation make the large-scale simulation practically impossible to run on a researcher’s workstation. QuakeCoRE started collaboration with New Zealand eScience Infrastructure(NeSI), the national high performance computing (HPC) provider to gain the necessary computational capacity and execution speed.

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  • Documenting natural hazard risk communication needs, challenges and innovations through participatory engagement

    Dohaney, Jacqueline; Wilson, Thomas; Bradley, Brendon; Brogt, Erik; Kennedy, Ben; Hudson-Doyle, Emma; Johnston, David (2016)

    Conference poster
    University of Canterbury Library

    Engineers often receive limited or no formal training in risk communication and may not have time to be up to date with current communication research. Additionally, communication training of practitioners is often 1-dimensional and recipe-style, and doesn’t explore contextual and situational nature of communication. Over the past couple of years, we have developed innovative curricula to teach risk and crisis communication to upper year geoscience, emergency management and engineering students at the University of Canterbury and affiliated institutions in New Zealand. This research involved measuring students’ communication performances and building a new model for understanding how communication is learned, resulting in statistically significant improvements of students’ perceptions and confidence. There is considerable experience and innovation within the New Zealand natural hazard risk communication community, so we aim to integrate this knowledge with our research as a ‘value add’ project (funded by EQC and QuakeCoRE), in which we will work with practitioners to create joint recommendations for improving risk and crisis communication, for the benefit of the wider community. In this poster, we will share the ‘lessons learned’ from our communication training experiences, and why they are important for teaching scientists and engineers how to communicate. Additionally, we will highlight some preliminary findings from engaging with professionals and ask the QuakeCoRE community to consider working with us on this important initiative. Lastly, we will highlight the successes and failures of running our knowledge transfer initiative, which is useful for professionals and organisations hoping to improve communication skills in engineering and the sciences.

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  • Effects of realistic fault geometry on simulated ground motions in the 2010 Darfield Earthquake

    Razakindrakoto, Hoby; Bradley, Brendon; Graves, R.W. (2016)

    Conference poster
    University of Canterbury Library

    Source representation is an essential component of physics-based ground motion simulations. However, its inherent non-uniqueness leads to different representations for the same fault rupture. For the 2010 Darfield earthquake, various source models have been proposed that primarily differ in fault geometry and rupture process.

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  • Seismic hazard analysis and ground motion selection considering directivity effects

    Tarbali, Karim; Bradley, Brendon; Baker, Jack W. (2016)

    Conference poster
    University of Canterbury Library

    Selecting appropriate ground motion ensembles is a key step in assessing the seismic performance of engineered systems through time-domain seismic response analyses. Recent developments in earthquake rupture forecast and ground motion models (GMMs) provide the engineering community with advanced empirical models to consider physical processes such as rupture directivity in seismic hazard calculations. This study presents an example application of such models to assess the seismic hazard in the near-fault region and subsequently select ground motion ensembles that appropriately represent the target hazard. Implications of the variability in the selected ground motion characteristics are discussed in terms of the demand hazard and collapse fragility.

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  • QuakeCoRE and OpenSees (Year 1): Optimisation of Source Code, Pre- and Post-Processing Tools, and Community Development

    McGann, Chris; Jeong, Seokho; Bradley, Brendon; Tarbali, K.; Wotherspoon, Liam; Lagrava, D.; Bae, Sung Eun (2016)

    Conference poster
    University of Canterbury Library

    The OpenSees finite element platform (Open System for Earthquake Engineering Simulation) developed through the University of California Berkeley is the principal collaborative software identified by QuakeCoRE Technology Platform 4 for use in detailed seismic response modelling of individual infrastructure components. OpenSees was selected for this purpose due to its capabilities as an open-source platform for sequential and parallel analysis of both geotechnical and structural systems. OpenSees is one of the few tools available with all of these attributes, and due to this unique combination of features it meets all three of the underlying principles identified for QuakeCoRE Technology Platform 4: it is open-source, it is scalable (able to make use of HPC resources), and it is flexible (works for variety of problem types and able to work with other QuakeCoRE software modules).

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  • Methods for Incorporating Soil Nonlinearity in Ground Motion Simulation

    de la Torre, Chris; Bradley, Brendon; Jeong, Seokho; McGann, Chris (2016)

    Conference poster
    University of Canterbury Library

    This poster discusses several possible approaches by which the nonlinear response of surficial soils can be explicitly modelled in physics-based ground motion simulations, focusing on the relative advantages and limitations of the various methodologies. These methods include fully-coupled 3D simulation models that directly allow soil nonlinearity in surficial soils, the domain reduction method for decomposing the physical domain into multiple subdomains for separate simulation, conventional site response analysis uncoupled from the simulations, and finally, the use of simple empirically based site amplification factors We provide the methodology for an ongoing study to explicitly incorporate soil nonlinearity into hybrid broadband simulations of the 2010-2011 Canterbury, New Zealand earthquakes.

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  • A V s30 Map for New Zealand based on surficial geology, topography and direct measurements

    Foster, Kevin; Bradley, Brendon; Wotherspoon, Liam; McGann, Chris (2016)

    Conference poster
    University of Canterbury Library

    When designing structures to withstand future earthquakes, the potential damage resulting from a range of hypothetical future earthquake scenarios must be estimated. The influence of local geology on observed ground motions has an outsized role in affecting observed ground motions; it is commonly quantified simplistically with the parameter V s30 (time-averaged 30m depth vertical shear wave velocity). We are developing a continuous V s30 map for New Zealand, using multiple datasets. The map will be useful in routine engineering analyses, in building code updates, and in research on site response and ground motion simulation.

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  • Ground Motion Simulation Validation using Small-to-Moderate Magnitude Events in the Canterbury, New Zealand Region

    Lee, Robin L.; Bradley, Brendon; Jeong, Seokho; Razafindrakoto, Hoby; Thomson, Ethan (2016)

    Conference poster
    University of Canterbury Library

    This poster presents work to date on ground motion simulation validation and inversion for the Canterbury, New Zealand region. Recent developments have focused on the collection of different earthquake sources and the verification of the SPECFEM3D software package in forward and inverse simulations. SPECFEM3D is an open source software package which simulates seismic wave propagation and performs adjoint tomography based upon the spectral-element method. Figure 2: Fence diagrams of shear wave velocities highlighting the salient features of the (a) 1D Canterbury velocity model, and (b) 3D Canterbury velocity model. Figure 5: Seismic sources and strong motion stations in the South Island of New Zealand, and corresponding ray paths of observed ground motions. Figure 3: Domain used for the 19th October 2010 Mw 4.8 case study event including the location of the seismic source and strong motion stations. By understanding the predictive and inversion capabilities of SPECFEM3D, the current 3D Canterbury Velocity Model can be iteratively improved to better predict the observed ground motions. This is achieved by minimizing the misfit between observed and simulated ground motions using the built-in optimization algorithm. Figure 1 shows the Canterbury Velocity Model domain considered including the locations of small-to-moderate Mw events [3-4.5], strong motion stations, and ray paths of observed ground motions. The area covered by the ray paths essentially indicates the area of the model which will be most affected by the waveform inversion. The seismic sources used in the ground motion simulations are centroid moment tensor solutions obtained from GeoNet. All earthquake ruptures are modelled as point sources with a Gaussian source time function. The minimum Mw limit is enforced to ensure good signal-to-noise ratio and well constrained source parameters. The maximum Mw limit is enforced to ensure the point source approximation is valid and to minimize off-fault nonlinear effects.

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  • Assessing the seismic resilience of an underground lifeline: Case study of the Christchurch City potable water network

    Bellagamba, Xavier; Bradley, Brendon; Hughes, Matthew W.; Wotherspoon, Liam (2016)

    Conference poster
    University of Canterbury Library

    essential systems upon which the well-being and functioning of societies depend. They deliver a service or a good to the population using a network, a combination of spatially-distributed links and nodes. As they are interconnected, network elements’ functionality is also interdependent. In case of a failure of one component, many others could be momentarily brought out-of-service. Further problems arise for buried infrastructure when it comes to buried infrastructure in earthquake and liquefaction-prone areas for the following reasons: • Technically more demanding inspections than those required for surface horizontal infrastructure • Infrastructure subject to both permanent ground displacement and transient ground deformation • Increase in network maintenance costs (i.e. deterioration due to ageing material and seismic hazard) These challenges suggest careful studies on network resilience will yield significant benefits. For these reasons, the potable water network of Christchurch city (Figure 1) has been selected for its well-characterized topology and its extensive repair dataset.

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  • Comparisons between deterministic and probabilistic liquefaction assessment approaches

    Lacrosse, V.; van Ballegooy, S.; Bradley, Brendon (2016)

    Conference poster
    University of Canterbury Library

    Liquefaction assessments are commonly undertaken by geotechnical engineers using a deterministic approach. This approach does not appropriately take into account the significant uncertainties associated with a liquefaction assessment and can potentially compound the conservatism that is introduced when selecting input parameters. Therefore, the deterministic assessment approach can be conservative and the expected performance poorly understood. This research project looks at an alternative approach for liquefaction assessments – a probabilistic assessment. Other researchers have hypothetically experimented with the idea, but have never operationalised a probabilistic approach.

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