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Research papers, University of Canterbury Library

This report presents the simplified seismic assessment of a case study reinforced concrete (RC) building following the newly developed and refined NZSEE/MBIE guidelines on seismic assessment (NZSEE/MBIE, semi-final draft 26 October 2016). After an overview of the step-by-step ‘diagnostic’ process, including an holistic and qualitative description of the expected vulnerabilities and of the assessment strategy/methodology, focus is given, whilst not limited, to the implementation of a Detailed Seismic Assessment (DSA) (NZSEE/MBIE, 2016c). The DSA is intended to provide a more reliable and consistent outcome than what can be provided by an initial seismic assessment (ISA). In fact, while the Initial Seismic Assessment (ISA), of which the Initial Evaluation Procedure is only a part of, is the more natural and still recommended first step in the overall assessment process, it is mostly intended to be a coarse evaluation involving as few resources as reasonably possible. It is thus expected that an ISA will be followed by a Detailed Seismic Assessment (DSA) not only where the threshold of 33%NBS is not achieved but also where important decisions are intended that are reliant on the seismic status of the building. The use of %NBS (% New Building Standard) as a capacity/demand ratio to describe the result of the seismic assessment at all levels of assessment procedure (ISA through to DSA) is deliberate by the NZSEE/MBIE guidelines (Part A) (NZSEE/MBIE 2016a). The rating for the building needs only be based on the lowest level of assessment that is warranted for the particular circumstances. Discussion on how the %NBS rating is to be determined can be found in Section A3.3 (NZSEE/MBIE 2016a), and, more specifically, in Part B for the ISA (NZSEE/MBIE 2016b) and Part C for the DSA (NZSEE/MBIE 2016c). As per other international approaches, the DSA can be based on several analysis procedures to assess the structural behaviour (linear, nonlinear, static or dynamic, force or displacement-based). The significantly revamped NZSEE 2016 Seismic Assessment Guidelines strongly recommend the use of an analytical (basically ‘by hand’) method, referred to the Simple Lateral Mechanism Analysis (SLaMA) as a first phase of any other numerically-based analysis method. Significant effort has thus been dedicated to provide within the NZSEE 2016 guidelines (NZSEE/MBIE 2016c) a step-by-step description of the procedure, either in general terms (Chapter 2) or with specific reference to Reinforced Concrete Buildings (Chapter 5). More specifically, extract from the guidelines, NZSEE “recommend using the Simple Lateral Mechanism Analysis (SLaMA) procedure as a first step in any assessment. While SLaMA is essentially an analysis technique, it enables assessors to investigate (and present in a simple form) the potential contribution and interaction of a number of structural elements and their likely effect on the building’s global capacity. In some cases, the results of a SLaMA will only be indicative. However, it is expected that its use should help assessors achieve a more reliable outcome than if they only carried out a detailed analysis, especially if that analysis is limited to the elastic range For complex structural systems, a 3D dynamic analysis may be necessary to supplement the simplified nonlinear Simple Lateral Mechanism Analysis (SLaMA).” This report presents the development of a full design example for the the implementation of the SLaMA method on a case study buildings and a validation/comparison with a non-linear static (pushover) analysis. The step-by-step-procedure, summarized in Figure 1, will be herein demonstrated from a component level (beams, columns, wall elements) to a subassembly level (hierarchy of strength in a beam-column joint) and to a system level (frame, C-Wall) assuming initially a 2D behaviour of the key structural system, and then incorporating a by-hand 3D behaviour (torsional effects).

Research Papers, Lincoln University

The earthquake swarm that has struck Canterbury, New Zealand from September 2010 has led to widespread destruction and loss of life in the city of Christchurch. In response to this the New Zealand government convened a Royal Commission under the Commissions of Inquiry Act 1908. The terms of reference for this enquiry were wide ranging, and included inquiry into legal and best-practice requirements for earthquake-prone buildings and associated risk management strategies. The Commission produced a final report on earthquake-prone buildings and recommendations which was made public on the 7th December 2012. Also on the 7th of December 2012 the Ministry of Business, Innovation and Employment (MBIE) released a Consultation Document that includes many of the recommendations put forward by the Royal Commission. This paper examines the evidence presented to the Royal Commission and reviews their recommendations and those of MBIE in relation to the management of earthquake-prone buildings. An analysis of the likely impacts of the recommendations and proposals on both the property market and society in general is also undertaken.

Research papers, University of Canterbury Library

A multi-disciplinary geo-structural-environmental engineering project funded by the Ministry of Business Innovation and Employment (MBIE) is being carried out at the University of Canterbury. The project aims at developing an eco-friendly seismic isolation foundation system which will improve the seismic performance of medium-density low-rise buildings. Such system is characterized by two main elements: 1) granulated scrap rubber mixed with gravelly soils to be placed beneath the structure, with the goal damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre reinforced rubberised concrete (SFRRuC) to enhance the flexibility and toughness of the foundation, looking at better accommodating the displacement demand. In this paper, the main objectives, scope and methodology of the project will be briefly described. A literature review of the engineering properties of steel-fibre reinforced rubberised concrete (RuC) will be presented. Then, preliminary results on concrete mixes with different rubber and steel fibres content will be exhibited.

Research papers, University of Canterbury Library

There is an increasing recognition that the seismic performance of buildings will be affected by the behaviour of both structural and non-structural elements. In light of this, work has been progressing at the University of Canterbury to develop guidelines for the seismic assessment of commercial glazing systems. This paper reviews the seismic assessment guidelines prescribed in Section C10 of the MBIE building assessment guidelines. Subsequently, the C10 approach is used to assess the drift capacity of a number of glazing units recently tested at the University of Canterbury. Comparing the predicted and observed drift capacities, it would appear that the C10 guidelines may lead to nonconservative estimates of drift capacity. Furthermore, the experimental results indicate that watertightness may be lost at very low drift demands, suggesting that guidance for the assessment of serviceability performance would also be beneficial. As such, it is proposed that improved guidance be provided to assist engineers in considering the possible impact that glazing could have on the structural response of a building in a large earthquake.

Research papers, University of Canterbury Library

Recent earthquakes in New Zealand proved that a shift is necessary in the current design practice of structures to achieve better seismic performance. Following such events, the number of new buildings using innovative technical solutions (e.g. base isolation, controlled rocking systems, damping devices, etc.), has increased, especially in Christchurch. However, the application of these innovative technologies is often restricted to medium-high rise buildings due to the maximum benefit to cost ratio. In this context, to address this issue, a multi-disciplinary geo-structural-environmental engineering project funded by the Ministry of Business Innovation and Employment (MBIE) is being carried out at the University of Canterbury. The project aims at developing a foundation system which will improve the seismic performance of medium-density low-rise buildings. Such foundation is characterized by two main elements: 1) granulated tyre rubber mixed with gravelly soils to be placed beneath the structure, with the goal of damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre rubberised concrete to enhance the flexibility of the foundation under differential displacement demand. In the first part of this paper, the overarching objectives, scope and methodology of the project will be briefly described. Then, preliminary findings on the materials characterization, i.e., the gravel-rubber mixtures and steel-fibre rubberised concrete mixes, will be presented and discussed with focus on the mechanical behaviour.

Audio, Radio New Zealand

Hon SIMON BRIDGES to the Prime Minister: Does she stand by all her Government’s policies and actions? KIRITAPU ALLAN to the Minister of Finance: What reports has he seen on the need for innovation in the New Zealand economy? Hon AMY ADAMS to the Minister of Finance: Does he agree with the Prime Minister’s comment, “I absolutely believe that our agenda will grow the economy, will make sure businesses are in a position to grow and prosper, because I need that economic growth to be able to lift the well-being of all New Zealanders”? Hon PAUL GOLDSMITH to the Minister for Economic Development: Does he still think the ANZ survey of business confidence is junk? Dr DUNCAN WEBB to the Minister of Justice: What recent announcements has he made about the Family Court? Hon MICHAEL WOODHOUSE to the Minister of Immigration: Does he stand by all of his statements and actions? JONATHAN YOUNG to the Minister of Energy and Resources: What advice, if any, did she receive in respect of the obligation to act in accordance with the Minerals Programme for Petroleum regarding the Government’s decision to offer no new offshore permits? ANDREW BAYLY to the Minister for Building and Construction: What procedures, if any, will she put into place to ensure Government agencies adhere to MBIE’s Government procurement guidelines for construction projects? Hon Dr NICK SMITH to the Minister of Justice: Does he stand by all of his statements on the Electoral (Integrity) Amendment Bill and the potential chilling effect it will have on the expression of dissenting views? CHRIS BISHOP to the Minister of Internal Affairs: Does she stand by all her statements around the Government inquiry into the appointment of the Deputy Commissioner of Police? Dr LIZ CRAIG to the Minister of Health: What confidence can the public take from the review of the National Bowel Screening Programme that was released this morning? STUART SMITH to the Minister of Justice: What advice, if any, has he received on the need for the Canterbury Earthquakes Insurance Tribunal?

Research Papers, Lincoln University

Initial recovery focus is on road access (especially the inland SH70) although attention also needs to be focussed on the timelines for reopening SH1 to the south. Information on progress and projected timelines is updated daily via NZTA (www.nzta.govt.nz/eq-travel ). Network analyses indicate potential day trip access and re-establishment of the Alpine Pacific triangle route. When verified against ‘capacity to host’ (Part 2 (15th December) there appears to potential for the reestablishment of overnight visits. Establishing secure road access is the key constraint to recovery. In terms of the economic recovery the Kaikoura District has traditionallyattracted a large number of visitors which can be grouped as: second home (and caravan) owners, domestic New Zealand and international travellers. These have been seen through a behaviour lens as “short stop”, ‘day” (where Kaikoura is the specific focal destination) and overnight visitors. At the present restricted access appears to make the latter group less amenable to visiting Kaikoura, not the least because the two large marine mammal operators have a strong focus on international visitors. For the present the domestic market provides a greater initial pathway to recovery. Our experiences in and reflections on Christchurch suggest Kaikoura will not go back to what it once was. A unique opportunity exists to reframe the Kaikoura experience around earthquake geology and its effects on human and natural elements. To capitalise on this opportunity there appears to be a need to move quickly on programming and presenting such experiences as part of a pathway to re-enabling domestic tourists while international visitor bookings and flows can be re-established. The framework developed for this study appears to be robust for rapid post disaster assessment. It needs to be regularly updated and linked with emerging governance and recovery processes.

Research papers, University of Canterbury Library

Between 2010 and 2011, Canterbury experienced a series of four large earthquake events with associated aftershocks which caused widespread damage to residential and commercial infrastructure. Fine grained and uncompacted alluvial soils, typical to the Canterbury outwash plains, were exposed to high peak ground acceleration (PGA) during these events. This rapid increase in PGA induced cyclic strain softening and liquefaction in the saturated, near surface alluvial soils. Extensive research into understanding the response of soils in Canterbury to dynamic loading has since occurred. The Earthquake Commission (EQC), the Ministry of Business and Employment (MBIE), and the Christchurch City Council (CCC) have quantified the potential hazards associated with future seismic events. Theses bodies have tested numerous ground improvement design methods, and subsequently are at the forefront of the Canterbury recovery and rebuild process. Deep Soil Mixing (DSM) has been proven as a viable ground improvement foundation method used to enhance in situ soils by increasing stiffness and positively altering in situ soil characteristics. However, current industry practice for confirming the effectiveness of the DSM method involves specific laboratory and absolute soil test methods associated with the mixed column element itself. Currently, the response of the soil around the columns to DSM installation is poorly understood. This research aims to understand and quantify the effects of DSM columns on near surface alluvial soils between the DSM columns though the implementation of standardised empirical soil test methods. These soil strength properties and ground improvement changes have been investigated using shear wave velocity (Vs), soil behaviour and density response methods. The results of the three different empirical tests indicated a consistent improvement within the ground around the DSM columns in sandier soils. By contrast, cohesive silty soils portrayed less of a consistent response to DSM, although still recorded increases. Generally, within the tests completed 50 mm from the column edge, the soil response indicated a deterioration to DSM. This is likely to be a result of the destruction of the soil fabric as the stress and strain of DSM is applied to the un‐mixed in situ soils. The results suggest that during the installation of DSM columns, a positive ground effect occurs in a similar way to other methods of ground improvement. However, further research, including additional testing following this empirical method, laboratory testing and finite 2D and 3D modelling, would be useful to quantify, in detail, how in situ soils respond and how practitioners should consider these test results in their designs. This thesis begins to evaluate how alluvial soils tend to respond to DSM. Conducting more testing on the research site, on other sites in Christchurch, and around the world, would provide a more complete data set to confirm the results of this research and enable further evaluation. Completing this additional research could help geotechnical DSM practitioners to use standardised empirical test methods to measure and confirm ground improvement rather than using existing test methods in future DSM projects. Further, demonstrating the effectiveness of empirical test methods in a DSM context is likely to enable more cost effective and efficient testing of DSM columns in future geotechnical projects.