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Auckland, New Zealand

Oliver S.,Holmes Consulting Group
Concrete (London) | Year: 2011

A detailed assessment was performed to strengthen the existing Auckland Civic Underground Car Park in New Zealand. The detailed assessment found that the existing roof level waterproof membrane and drainage systems had failed and the resulting water ingress and ponding was causing structural deterioration. It was concluded that the car park needed to be strengthened as part of the planned Aotea Square refurbishment works to enable full use of the square above. Fourteen different strengthening options were considered during the concept design phase for the roof strengthening works, including selected strengthening of existing elements and total roof removal and replacement. Structural steel, precast, and cast-in-situ concrete alternatives were considered for each of the options. A new steel-framed composite metal deck was constructed above the existing roof, with the existing primary beams strengthened to support 50% of the new roof. Source

Wijanto S.,Holmes Consulting Group | Clifton G.C.,University of Auckland
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2014

The recent series of damaging earthquakes in Christchurch, New Zealand has encouraged greater recognition of the post-earthquake economic impacts on New Zealand society and higher emphasis on low-damage earthquake resisting systems. Braced frames incorporating Buckling Restrained Braces (BRB) are seen as a significant contender for such a system. This research project focuses on the development of a reliable design procedure and detailing requirements for a generic BRB system. To gauge the performance of the designed system and to ascertain the reliability of the developed procedure, a series of static and dynamic sub-assemblage tests on the BRB frame with two different brace connection configurations were performed. The results are presented and discussed herein. The experimental tests generated stable and near symmetrical hysteresis loops, which is a principal characteristic of a well performing BRB system, albeit with the occurrence of slack in the connections. The experimental test results shows that several improvements need to be made to the proposed design procedure and detailing as outlined throughout the paper; especially the procedural modification to prevent slack from occurring in the two different connection systems. It is envisaged that applications will typically involve use of proprietary braces, however these need to be applied in accordance with the New Zealand design procedure; and determining the appropriate procedure was a key part of this project. Source

Galloway B.,Holmes Consulting Group | Ingham J.M.,University of Auckland
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2015

The South Napa earthquake occurred on Sunday, 24 August 2014 at 3.20 am local time at a depth of 10.7 km, having MW 6.0 and causing significant damage to unreinforced masonry (URM) buildings in the City of Napa and generating strong ground shaking in a region well known for its wine production. Parallels exist between the damage in past New Zealand earthquakes, particularly to unreinforced masonry buildings, and the disruption in the Marlborough region following the recent 2013 MW 6.5 Seddon earthquake. Furthermore, the event was the largest to have occurred in Northern California since the 1989 Loma Prieta earthquake 25 years earlier, and hence was an important event for the local community of earthquake researchers and professionals regarding the use of a physical and virtual clearinghouse for data archiving of damage observations. Because numerous URM buildings in the City of Napa had been retrofitted, there was significant interest regarding the observed performance of different retrofitting methods. Following a brief overview of the earthquake affected area and previous earthquakes to have caused damage in the Napa Valley region, details are provided regarding the characteristics of the 2014 South Napa earthquake, the response to the earthquake including placarding procedures and barricading, and more specific details of observed building and non-structural damage. Aspects of business continuity following the South Napa earthquake are also considered. One conclusion is that in general the seismic retrofitting of URM buildings in the Napa region proved to be very successful, and provides an important benchmark as New Zealand begins to more actively undertake seismic assessment and retrofitting of its earthquake prone building stock. It is also concluded that there are sufficient similarities between New Zealand and California, and a rich network of contacts that has developed following the hosting of many US visitors to New Zealand in conjunction with the 2010/2011 Canterbury earthquakes, that it is sensible for the New Zealand earthquake engineering community to maintain a close focus on ongoing earthquake preparedness and mitigation methods used and being developed in USA, and particularly in California. Source

Ahmadi A.,University of Auckland | Mathieson C.,Holmes Consulting Group | Clifton G.C.,University of Auckland | Das R.,University of Auckland | Lim J.B.P.,University of Auckland
Journal of Constructional Steel Research | Year: 2016

This paper describes an experimental investigation on a novel hollow connector, to be referred to as the Howick Rivet Connector (HRC). The HRC is of diameter of 12.75 mm and thickness of 0.95 mm and can be used to connect cold-formed steel channel-sections with a gap, such as found in the connection arrangement of cold-formed steel trusses and seismic framing units. Laboratory tests on twenty-seven Tee-stub specimens that use the HRC are described; for comparison, another twenty-seven Tee-stub specimens are also tested that use standard bolts. In the laboratory tests, the effect of three different thicknesses of channel-sections and three different end distances are investigated. It is shown that the behaviour of the HRC Tee-stubs is similar to that of the bolted Tee-stubs, but possess a higher capacity and an improved ductility, as shown by a longer yield plateau once the connection becomes inelastic. It recommended that a minimum end distance of 1.5 times the diameter of the HRC is sufficient. Design equations that can be used to predict the bearing strength of the HRC Tee-stubs are proposed; for these equations, the index of reliability calculated was greater than the recommended 3.5. © 2016 Elsevier Ltd. All rights reserved. Source

Peng B.H.H.,Holmes Consulting Group | Dhakal R.P.,University of Canterbury | Fenwick R.C.,University of Canterbury | Carr A.J.,University of Canterbury | Bull D.K.,University of Canterbury
Journal of Structural Engineering (United States) | Year: 2013

This paper describes the development and validation of an analytical multispring plastic hinge element that can predict elongation of ductile RC plastic hinges together with its flexural and shear responses. The element consists of layers of longitudinal and diagonal springs that represent the behavior of concrete, reinforcing bars, and diagonal compression struts. Beam tests reported in the literature, for which elongation of plastic hinges was measured at different stages of the lateral cyclic loading, were used to validate the effectiveness of the newly developed plastic hinge element. Comparisons of the analytical predictions with experimental results show that the proposed element predicts elongation of plastic hinges satisfactorily. The ability of the model to predict elongation of a plastic hinge together with its flexural and shear deformations offers a significant advancement in seismic performance assessment of RC structures. © 2013 American Society of Civil Engineers. Source

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