Mandeno W.,Opus International Consultants Ltd.
Annual Conference of the Australasian Corrosion Association 2012 | Year: 2012
Thermally sprayed metal (TSM) includes proven long term protective coating systems for steelwork in a marine environment such as thermal sprayed zinc (TSZ) and thermal sprayed aluminium (TSA); however specifiers have been slow to adopt these in Australia. This paper reviews the technology then looks at several projects in New Zealand and overseas, some where a premature failure has occurred, and discusses these and the lessons that should be learned. It concludes with recommendations as to how coating specifications could be improved so that TSM's potential long life performance can be achieved. Copyright © (2012) by the Australasian Corrosion Association.
Gerbrandt R.C.,Opus International Consultants Ltd.
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2014
The Tauroa residential subdivision is situated in the hills of southern Havelock North in Hawke's Bay, New Zealand. The development proposal includes removal of a moderately deep (<10 m) landslide and its replacement with an engineered fill slope. A simplified "screening analysis" method was utilised to develop reduced equivalent horizontal seismic loads for use in a pseudo-static slope stability assessment of the proposed remedial engineered fill slope. This risk-based method allows limited slope deformations to occur as a result of the design seismic event, with the magnitudes of the allowable slope deformations set in accordance with the tolerance level of the proposed development.
McCarten P.S.,Opus International Consultants Ltd.
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management | Year: 2010
The New Zealand Transport Agency Bridge Manual requires composite steel girder-concrete slab bridge beams to be assessed to the NZS 3404 Steel Design requirements. To account for shear connector fracture this standard limits the shear connection capacity for partially composite beams to 50% of that required for a fully composite beam. This criterion is unduly severe often requiring load restrictions to be applied and this typically does not correlate with bridge performance. Simplified plastic analysis methods for determining the flexural strength of a steel girder-concrete slab bridge beam requires the shear connector strength to be assessed using static failure modes, being concrete bearing and shear connector shear strength, either in the gross section or fixing to the steel girder flange. Shear connector fracture is also a critical limit state through the partial composite beam transition and needs to be appropriately assessed. The paper summarises "desk top research" reviewing trends in the flexural capacity versus shear connection capacity interaction curves for composite beams with the neutral axis in either the concrete slab or the steel beam. This review has shown the reliability of the shear connector capacity can be used to model the shear connector fracture limit state through the transition, a discrete smoothed empirical transition model is rational and repeatable and for NZS 3404 Steel Design an approximate 20% increase in load carrying capacity can be achieved with this typically negating the need to load restrict bridge beams Calibration of the model is limited and further testing is suggested to confirm the appropriateness of the evaluation procedure. © 2010 Taylor & Francis Group, London.
McFarlane P.,Opus International Consultants Ltd.
2013 International No-Dig Downunder | Year: 2013
The city of Christchurch has suffered a series of earthquakes which started in September 2010, and which have continued to this day. The effect on the visible built environment of the city is very obvious. Less visible, but equally serious, is the destructive effect these earthquakes have had on the unseen underground utilities. This paper discusses the rehabilitation of the brick barrel pipe network under Christchurch's Central City area which has been undertaken by the Stronger Christchurch Infrastructure Rebuild Team (SCIRT). More than 10km of brick barrel pipes, serving the stormwater and wastewater systems, have been inspected and rehabilitated using a range of trenchless techniques, adapted for optimum performance in seismic conditions. The pipes range in size from 400mm to 1,100mm diameter and consist of round, oval and egg shaped pipes. The design of the rehabilitation works commenced in early 2012. The majority of the physical rehabilitation was completed by early 2013. Completing the project in this short timeframe necessitated the use of a collaborative, integrated approach that places importance on health & safety, disruption reduction, risk mitigation and innovation. The paper discusses: · Selection of appropriate and cost-effective rehabilitation methodologies · Selection of specialist contractors · Liner design for earthquakes · Implementation of the physical works programme.
Montakhab A.,Opus International Consultants Ltd. |
Yusuf B.,University Putra Malaysia |
Folkard A.M.,Lancaster University
Proceedings of the Institution of Civil Engineers: Water Management | Year: 2015
The distribution of aquatic vegetation within conveyance channels plays a key role in the determination of their hydraulic characteristics, especially where the vegetation is patchy, as is commonly found in nature. This paper reports the results of a laboratory flume study on flow and turbulence conditions caused by patches of the emergent rush Lepironia articulata. Acoustic Doppler velocimeter measurements were taken within and downstream of single-and multiple-patch configurations of this plant, and the effects of varying incident flow rate (0-16-0-32 m/s) and stem-scale porosity (12-4% solid volume fraction) were investigated. The results showed that flow encountering a single patch formed a turbulent wake downstream of the vegetation. Within this wake, the Reynolds stress increased downstream initially, and then decayed. When a second patch was positioned within the region of maximum Reynolds stress, the Reynolds stress decreased by between 25 and 50%. The amount of this reduction was dependent on the porosity of the vegetation and the flow rate, and was greater at lower flow rates and porosities. These changes in turbulent flow fields around patches of emergent vegetation are likely to be important in determining sediment budgets in their vicinity. ©.ICE Publishing: All rights reserved.