Omenzetter P.,University of Aberdeen |
Mangabhai P.,Watercare |
Singh R.,Beca |
Orense R.,University of Auckland
Journal of Civil Structural Health Monitoring | Year: 2014
To facilitate quick post-earthquake assessment of bridge condition, monitoring systems can be installed onto structures. However, due to high cost it is impractical to monitor all bridges within a network. Bridges which are exposed to increased hazards, are vulnerable and have high failure consequences pose the greatest risk to network functionality should they fail in a seismic event, and would therefore benefit the most from implementation of monitoring systems and quick condition assessment methodologies. This paper outlines a methodology to prioritise bridges for monitoring and quick condition assessment based on their seismic risk. The methodology uses four factors to determine risk, i.e. seismic hazard, vulnerability, failure impact and uncertainty of available data and assessment methods. The hazard factor accounts for the seismicity levels at bridge sites and length of time of exposure to hazard. Structural and geotechnical aspects have been combined to determine the vulnerability of each bridge. Impacts quantify the consequences of bridge failure on safety and network functionality. The uncertainty premium accounts for the quality, variability and limitations of data and risk assessment methods used. The overall risk calculated for each bridge within a stock enables prioritisation of structures for monitoring and quick post-disaster assessment. The whole spectrum of approaches to bridge monitoring and condition evaluation comprises bridge specific monitoring data used for quick and accurate analyses for the most critical, high risk bridges; data sourced from wide-area strong motion arrays used for quick but less accurate assessment for medium risk structures; and traditional visual inspection based assessment of low risk bridges. A discrete scoring system was adopted and detailed tables that enable scoring the hazards, vulnerabilities, impacts and data and assessment uncertainties developed. The proposed methodology was applied to a selection of bridges from the city of Wellington, New Zealand to test its applicability and performance. A comparative study with another seismic risk assessment method was also conducted. The results showed that the methodology effectively prioritised bridges depending on seismic risk. The methodology was also able to determine if risk at a particular bridge site was predominantly related to hazard, structural vulnerability, geotechnical vulnerability or impact. The methodology is simple, quick and flexible and can be adapted based on the level of accuracy required. The uncertainty premium allows risk to be determined given variable data and assessment method quality which has the benefit of being able to tailor data collection and assessment to the needs of each network and available resources. © 2014, Springer-Verlag Berlin Heidelberg.
Henville C.F.,Henville Consulting Inc. |
2012 IEEE International Conference on Power System Technology, POWERCON 2012 | Year: 2012
Addition of series compensation to transmission lines will increase the power transfer capabilities of the lines. However the existing transmission line protection systems on both the compensated lines and nearby uncompensated lines can be significantly affected. The security of the protection on the adjacent lines can be compromised and both the security and the dependability of the protection on the compensated line can also be threatened. When compensation is being considered for existing lines to increase their transfer capacity, the lowest cost solution would be to retain the existing protection systems with minimum modifications. This paper describes two studies that were completed to identify the minimum upgrade work required to ensure reliable protection applications and settings considering the impact of proposed series compensation projects. © 2012 IEEE.
Ross P.M.,University of Waikato |
Battershill C.N.,University of Waikato |
New Zealand Journal of Marine and Freshwater Research | Year: 2016
The October 2011 sinking of the container ship MV Rena on Astrolabe Reef, New Zealand, provided a rare opportunity to examine the fate of shipwreck-derived contaminants on an offshore rocky reef and food chain. Analyses of trace metals, polycyclic aromatic hydrocarbons (PAHs) and organotins indicated significant but localised contamination of Astrolabe Reef but not of nearby Mōtītī Island. Three years after the grounding, PAH concentrations were greater in sediments at Astrolabe (up to 131 mg kg−1) than at control locations, while organotins from the ship's antifouling hull paint were found exclusively in Astrolabe Reef sediments and biota. Over 80% of Astrolabe sediment samples contained tributyltin at concentrations above guideline sediment levels (>0.07 mg kg−1). Tributyltin and its decomposition products were also recorded in sea urchins, gastropods, lobster and fishes at concentrations up to 0.2 mg kg−1. Wreck and cargo-derived metals, particularly copper, tin and zinc, were present in some Astrolabe sediment samples above Australia and New Zealand Environment and Conservation Council guideline concentrations. However, there appeared to be only limited transmission of metals through the food chain. Copper, tin and zinc were recorded at greater concentrations in Astrolabe sea urchins and gastropods compared to control specimens, while metal concentrations in other biota were comparable across impact and control sites. Despite over 3 years having passed since the Rena grounding, the data series does not show any upward or downward trends in contaminant concentrations on Astrolabe Reef. Consequently, there is uncertainty about the long-term implications of the Rena grounding for the ecology of Astrolabe Reef. © 2016 The Royal Society of New Zealand.
Elwood K.J.,University of Auckland |
Pampanin S.,University of Canterbury |
Kam W.Y.,Beca |
Priestley N.,University of California at San Diego
Geotechnical, Geological and Earthquake Engineering | Year: 2014
At 12:51 pm local time on 22 February 2011, a Mw 6.2 aftershock of the September 4, 2010, Darfield Earthquake shook the city of Christchurch, New Zealand. The aftershock occurred on an unmapped fault less than 8 km from the city center resulting in the collapse of two reinforced concrete office buildings and one concrete parking garage, and severe damage to numerous others. The region has continued to suffer from aftershocks and further damage to building structures throughout the year following the February earthquake. This paper summarizes the observed damage to buildings in the Central Business District (CBD), with a specific focus on identifying future research to support the development of performance-based design procedures. © Springer Science+Business Media Dordrecht 2014.
Eligehausen R.,University of Stuttgart |
Mahrenholtz C.,Jordahl |
Akguzel U.,Beca |
Pampanin S.,University of Canterbury
American Concrete Institute, ACI Special Publication | Year: 2012
Bonded anchors consist of steel elements (e.g. threaded rods) which are bonded into a drilled hole by a prequalified adhesive mortar. They are designed according to ACI 318 Appendix D "Anchoring to Concrete". Reinforcing bars post-installed in drilled holes by a suitable mortar behave like cast-in reinforcing bars. They are designed according to ACI 318 Appendix A "Strut-and-Tie-Models" in connection with Chapter 12 "Development and Splices of Reinforcement". In a connection (e.g. concrete column to a foundation) cast-in or post-installed reinforcing bars transfer the tension force of the connected concrete structural member into the base member. This is also done by bonded anchors if a steel member is connected to a concrete structure. When assuming that the bond strength of cast-in or post-installed bars and of bonded anchors is about the same the required embedment depth of connections with straight reinforcing bars and bonded anchors should be about the same independent, if the connection is designed according to Appendix A or Appendix D. However, in many applications this is not the case. In the paper tests on column-foundation connections under monotonic and cyclic loading performed by the authors at the University of Canterbury are described. Used were cast-in hooked and straight deformed reinforcing bars and post-installed reinforcing bars. The measured failure loads are compared with predictions according to ACI 318, Chapter 12 (development length) and Appendix D (anchorages). Based on the results of the evaluations it is proposed to design connections of concrete members according to Appendix D and to amend the provisions in Chapter 12 and Appendix D to achieve a better agreement of the design results when using the two design models.
Claridge E.,Beca |
Spearpoint M.,University of Canterbury
Procedia Engineering | Year: 2013
New Zealand's Building Code has recently been amended and has introduced a new clause specific to fire-fighting operations that requires, amongst other things, that buildings must be designed and constructed to allow fire-fighters to reach the floor of fire origin and search the general area. The Code also specifies that for certain buildings they must be designed and constructed to allow fire-fighters to be able to first apply water to the fire before specified tenability criteria have been exceeded. These new requirements and other established performance-based fire engineering methods require the times associated with various fire brigade intervention tasks and specifically arrival times to be quantified. Currently there is limited data available to allow specific calculation of fire service response times to buildings. This paper presents response time and travel speed distributions to enable calculation of the time taken for the fire service to respond to notification of a fire and arrive at a specific location. Comparisons between response times within urban and rural fire districts are presented and between three of New Zealand's largest cities, their central business districts and outer suburbs. Distributions are presented and compared to existing values suggested by the Fire Brigade Intervention Model with data given to allow the assessment of the probability of attendance. © 2013 International Association for Fire Safety Science.
Holden C.,Institute of Geological & Nuclear Sciences |
Kaiser A.,Institute of Geological & Nuclear Sciences |
Van Dissen R.,Institute of Geological & Nuclear Sciences |
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2013
The Cook Strait earthquake sequence occurred in a region of known high seismicity. However, this was the strongest shaking felt in decades for the Wellington region and the top of the South Island. The location and size of the earthquake meant that the ground shaking was of rather short duration and moderate intensity, except for the epicentral region of the Lake Grassmere earthquake where a PGA of 0.7g was recorded, and for part of the Wellington foreshore where up to 0.2g was recorded in both earthquakes. The level of shaking in terms of response spectra was, in general, moderate except for very high "spiked" response at particular Wellington sites (WNK.S and VUWS) at periods of 0.4-0.5 seconds. Amplification and polarization in the NE-SW direction at approximately ∼1 s period at many Wellington stations is likely due to basin resonance effects, whereas dominant polarization in the NW-SE direction at shorter periods is consistent with a directivity effect, and is particularly evident in the Lake Grassmere earthquake. The earthquakes were not only a real-life test on the level of preparedness for the population but also on the behaviour of recently-built structures in the Wellington region that had not yet experienced a moderate earthquake. The ability to measure, analyse and understand the intensity and characteristics of the ground shaking coupled with well-documented damage to the buildings and building array recordings wilt hopefully foster collaboration across earthquake engineering disciplines.
Sims C.,BECA |
Orwin J.F.,University of Otago
Journal of Hydrology New Zealand | Year: 2011
Sustained summer snow melt from higher elevation catchments can be a significant source of runoff, particularly in regions with low summer rainfall. Little is known, however, about the timing and generation of snowmelt on the dry, fault-block mountains of Central Otago, New Zealand, where snowmelt is an important component of the water balance. To address this issue, meteorological, snow and runoff variables were measured in a 0.3 km2 tributary of the Leopold Burn on the Pisa Range, which is typical of the mountains of this region. Results of a point energy balance calculated for a mid-elevation site showed that the energy available for melt was primarily driven by net radiation. On average, net radiation provided 40% of the total energy available for melt, with the sensible heat flux contributing, on average, 34%. The estimated total water output over the 28 days of snowmelt was 746.59 mm water equivalent. The stage record from the catchment suggests that the melt period in this region is characterized by a single, sustained pulse of meltwater with a steep rising limb and subsequent decline. This hydrological response reflects an efficient response to positive energy inputs with, in this case, the complete removal of snow cover from the catchment in less than a month. This runoff response, coupled with a generally thin snowpack as a result of the medium elevation of the fault-block mountains, suggests that summer river flows in Central Otago could be particularly responsive to any long-term changes in winter precipitation patterns. © New Zealand Hydrological Society (2011).
Sparrow M.,Parsons Brinckerhoff |
Tucker S.,Beca |
Hobson A.,Parsons Brinckerhoff
14th Australasian Tunnelling Conference 2011: Development of Underground Space, Proceedings | Year: 2011
The Victoria Park Tunnel project is an inner-city alliance project in central Auckland, New Zealand. The existing two-directional viaduct will be modified to single-direction flow, and a new northbound 440 m cut and cover tunnel will be constructed beneath Victoria Park. Three-dimensional (3D) visualisation media were used to communicate key design innovations to stakeholders and the general public. The 3D visual material has proven a useful tool for informing motorists of a new safety barrier method adopted for traffic management. This presentation will explain how 3D visualisation was incorporated in the project and will showcase the 3D visualisation media created for the project.
Kerr A.,Beca |
20th ITS World Congress Tokyo 2013 | Year: 2013
The New Zealand Transport Agency (NZTA) commissioned Beca Infrastructure Ltd (Beca) to undertake a proof of concept study into the use of various sources of commercial vehicle data to enhance the understanding of freight activity across the country's road network. Having completed an investigation into sources of freight data currently available in New Zealand, the GPS data collected by an electronic Road User Class (eRUC) provider was selected as the basis of the proof of concept study. This paper provides a summary of the findings of this study and the future developments planned to provide an overview as to how fleet GPS data can be used to report on vehicle movements and inform the asset management process.