Bulletin of the New Zealand Society for Earthquake Engineering 2019-08-21T10:57:39+12:00 Rajesh Dhakal Open Journal Systems <p>Bulletin of the New Zealand Society for Earthquake Engineering</p> The 2014 South Napa earthquake and its relevance for New Zealand 2019-08-21T10:57:39+12:00 Bruce Galloway Jason M. Ingham <p>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.</p> <p>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.</p> 2015-03-31T00:00:00+13:00 Copyright (c) 2015 Bruce Galloway, Jason M. Ingham URM bearing wall building seismic risk mitigation on the west coast of the United States 2019-08-21T10:57:01+12:00 Brandon Paxton Fred Turner Ken Elwood Jason M. Ingham <p>Unreinforced masonry (URM) buildings are the most common target for seismic risk mitigation programmes, due to their long history of poor seismic performance. While seismic risk mitigation must make use of sound engineering methodologies, good public policy is at the heart of successful programmes. Past URM seismic risk mitigation efforts on the west coast of the United States are summarized herein, as valuable insights have been gained from both successful and unsuccessful programmes. Programme details such as compliance deadlines, retrofit design techniques, and retrofit/demolition rates are provided for cities throughout California, Oregon and Washington states, and the overall observed effectiveness of mandatory versus non-mandatory seismic strengthening programmes is discussed.</p> 2015-03-31T00:00:00+13:00 Copyright (c) 2015 Brandon Paxton, Fred Turner, Ken Elwood, Jason M. Ingham Floor diaphragms and a truss method for their analysis 2019-08-21T10:56:23+12:00 J.M. Scarry <p>Floor diaphragms form a critical component of seismic resistant buildings, but unfortunately, in the main their analysis and design in New Zealand leaves much to be desired. No worse example exists than the CTV Building in Christchurch. Despite the critical importance of diaphragms, there is a paucity of code provisions and design guidance relating to them.</p> <p>Using generic examples, the author describes a number of common diaphragm design deficiencies. These include diaphragms where valid load paths do not exist; diaphragms where the floors are not properly connected to the lateral load resisting elements, diaphragms that lack adequate flexural capacity and where re-entrant corners are not properly accounted for, and transfer diaphragms into which the reactions from the walls above cannot be properly introduced or transmitted.</p> <p>Three main types of seismic diaphragm action are discussed – ‘inertial,’ ‘transfer’ and ‘compatibility.’ These are, respectively, the direct inertial load on a floor that must be carried back to the lateral load resisting elements, the transfer forces that occur when major changes in floor area and lateral load resisting structure occur between storeys, and the compatibility forces that must exist to force compatible displacements between incompatible elements, such as shear walls or braced frames and moment frames, or as a result of redistribution.</p> <p>The author presents a simple Truss Method that allows complex diaphragms to be analysed for multiple load cases, providing accurate force distributions without the multiple models that conventional strut and tie methods would require. Being a type of strut and tie method, the Truss Method is compliant with requirements in NZS3101:2006 [1] to use strut and tie models for the analysis and design of certain aspects of diaphragm behaviour.</p> 2015-03-31T00:00:00+13:00 Copyright (c) 2015 J.M. Scarry Suitability of CFT columns for New Zealand moment frames 2019-08-21T10:55:45+12:00 Ponpong Chunhaviriyakul Gregory A. MacRae Dave Anderson G. Charles Clifton Roberto T. Leon <p>Composite steel-concrete construction uses steel and concrete together to provide the possibility of a system with better performance, and/or lower cost, than using either material alone. This paper firstly subjectively evaluates the advantages and disadvantages of a number of composite concrete filled tubular (CFT) column-connection systems proposed/used around the world in terms of their likely acceptance in moment frames in New Zealand. Then, the cost of a conventional one-way moment-resisting steel frame system is compared with a similarly behaving frame using rectangular concrete filled steel tubular (CFT) columns. It is shown for these studies conducted on one-way frames that composite CFT column construction with beam end-plate connections is generally more expensive than conventional steel column construction.</p> 2015-03-31T00:00:00+13:00 Copyright (c) 2015 Ponpong Chunhaviriyakul, Gregory A. MacRae, Dave Anderson, G. Charles Clifton, Roberto T. Leon