https://bulletin.nzsee.org.nz/index.php/bnzsee/issue/feed Bulletin of the New Zealand Society for Earthquake Engineering 2022-12-02T23:13:40+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/1522 Key Drivers in Using Low Damage Seismic Designs in Christchurch Buildings 2022-01-23T23:16:46+13:00 Juliet Skidmore jcamskidmore@gmail.com Gabriele Granello gabriele.granello@gmail.com Alessandro Palermo Alessandro.palermo@canterbury.ac.nz <p class="Summary">Following the extensive damage to Christchurch’s infrastructure in the 2010 and 2011 Canterbury earthquakes, a complete rebuild of the city centre has been undertaken, with a particular focus on seismic-resilient buildings. This paper explores the application of different seismic-resilient technologies to buildings in Christchurch, by interviewing the structural engineers responsible for the design of six case study structures. Focus is given to the structural performance and benefits of each technology, and the key factors driving the clients’ and engineers’ decision to use the system. Comparisons are then made between resilient technologies, looking at the relative construction times and cost, areas of difficulty in design and construction, and the expected performance. Assessments are made of the knowledgeability of stakeholders, including clients and engineers, in resilient design, and the aspects that need to be addressed in the ongoing research and development of new and existing resilient technologies.</p> <p class="Summary">Results show that the main factors identified driving clients’ and engineers’ decisions to use a seismic-resilient design were the structural performance, ease of construction and publicity. Key issues that need to be addressed during the development of new resilient systems are the durability, constructability and cost of a design, in addition to the production of design and construction aids, to both support engineers and contractors in the process, and encourage them to undertake a seismic-resilient design. Ideas are presented for increasing client and public awareness of different resilient systems available so that the demand and commission for seismic-resilient buildings in the city may increase.</p> 2022-12-02T00:00:00+13:00 Copyright (c) 2022 Juliet Skidmore, Gabriele Granello, Alessandro Palermo https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1569 Estimating fire following earthquake risk for Wellington City, New Zealand 2022-02-08T22:54:23+13:00 Finn Scheele f.scheele@gns.cri.nz Biljana Lukovic b.lukovic@gns.cri.nz Jose Moratalla j.moratalla@gns.cri.nz Alexandre Dunant alexandre.dunant@durham.ac.uk Nick Horspool n.horspool@gns.cri.nz <p>Fire following earthquake (FFE) is a significant hazard in urban areas subject to high seismicity. Wellington City has many characteristics that make it susceptible to ignitions and fire spread. These include proximity to major active faults, closely spaced timber-clad buildings, vulnerable water and gas infrastructure, frequent high winds and challenging access for emergency services. We modelled the ignitions, fire spread and suppression for five earthquake sources. Uncertainty in ground motions, the number and location of ignitions, weather conditions and firefighting capacity were accounted for. The mean loss per burn zone (area burnt due to ignition and fire spread) is $46m without fire suppression, indicating the potential property damage avoided by controlling the fire spread. The mean total loss for earthquake scenarios ranges from $0.28b for the Wairau Fault through to $3.17b for a Hikurangi Subduction Zone scenario, including the influence of fire suppression. Wind speed has a strong influence on the potential losses for each simulation and is a more significant factor than the number of ignitions for evaluating losses. Areas in Wellington City of relatively high risk are identified, which may inform risk mitigation strategies. The models may be applied to other urban areas.</p> 2022-12-02T00:00:00+13:00 Copyright (c) 2022 Finn Scheele, Biljana Lukovic, Jose Moratalla, Alexandre Dunant, Nick Horspool https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1526 Implications of Siesmic Detailing on the Fire Performance of Post-Tensioned Timber Frames 2022-03-11T16:47:47+13:00 Paul Horne paul.horne@pg.canterbury.ac.nz Alessandro Palermo alessandro.palermo@canterbury.ac.nz Anthony Abu anthony.abu@canterbury.ac.nz Peter Moss peter.moss@canterbury.ac.nz <p>Post-Tensioned Timber (PTT) frames have significant advantages over traditional timber frame systems especially where a low damage design and fast construction are desired. New Zealand practitioners designing timber structures for fire are accustomed to applying ambient design methods to an element cross-section reduced by a char depth based on a duration of Standard Fire exposure following NZS 3603 or AS/NZS 1720.4. The behaviour of PTT frames in fire remains a concern because this approach does not account for the actual mechanics of PTT connection and frame response under natural fires that will occur in the structure. This paper examines the individual and interdependent response of PTT connection components (tendon, dissipater, fasteners, etc) to fire. It is shown that the ambient analysis tool for PTT connections, the Modified Monolithic Beam Analogy, cannot be applied to the fire case by only using char reduced cross-sections of timber elements. This approach of combining ambient methodologies with reduced cross-sections does not account for the specific connection detailing, which result in unique damage in fire that may govern the structural response. The responses of two seismically detailed PTT connections are predicted using this approach and compared to a first principles assessment of connection behaviour to demonstrate that failure will occur earlier than otherwise predicted. Numerical thermal analyses of these two connections also qualitatively corroborate the damage that occurs. This investigation establishes that additional studies are required to understand the complex behaviour of these connections when exposed to fire before a design methodology can be developed.</p> 2022-12-02T00:00:00+13:00 Copyright (c) 2022 Paul Horne, Alessandro Palermo, Anthony Abu, Peter Moss https://bulletin.nzsee.org.nz/index.php/bnzsee/article/view/1552 Evaluation of a geospatial liquefaction model using land damage data from the 2016 Kaikōura earthquake 2022-03-18T09:23:58+13:00 Amelia Lin alin116@aucklanduni.ac.nz Liam Wotherspoon l.wotherspoon@auckland.ac.nz Jason Motha jason.motha@canterbury.ac.nz <p>The paper uses two geospatial liquefaction models based on (1) global and (2) New Zealand specific variables such as Vs30, precipitation and water table depth to estimate liquefaction probability and spatial extent for the 2016 Kaikōura earthquake. Results are compared to observational data, indicating that the model based on global variables underestimates liquefaction manifestation in the Blenheim area due to the low resolution of the input datasets. Furthermore, a tendency for underprediction is evident in both models for sites located in areas with rapidly changing elevation (mountainous terrain), which is likely caused by the low resolution of the elevation-dependent variables Vs30 and water table depth leading to incorrect estimates. The New Zealand specific model appears to be less sensitive to this effect as the variables provide a higher resolution and a better representation of region specific characteristics. However, the results suggest that the modification might lead to an overestimation of liquefaction manifestation along rivers (e. g. Kaikōura). An adjustment of the model coefficients and / or the integration of other resources such as geotechnical methods can be considered to improve the model performance. The evaluation of the geospatial liquefaction models demonstrates the importance of high resolution input data and leads to the conclusion that the New Zealand specific model should be preferred over the original model due to better prediction performance. The findings provide an overall better understanding on the models’ applicability and potential as a tool to predict liquefaction manifestation for future hazard assessments.</p> 2022-12-02T00:00:00+13:00 Copyright (c) 2022 Amelia Lin, Liam Wotherspoon, Jason Motha