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Research papers, University of Canterbury Library

Worldwide turbidity is a huge concern for the health of aquatic ecosystems. Human activities on the land such as construction, deforestation, agriculture, and mining all have impacts on the amount of particulate solids that enter the world’s waterways. These particulate solids can pose a number of risks to aquatic life, but primary among them is the turbidity that they create in the water column. The way suspended solids interact with light creates cloudiness in the water which interferes with the vision, and visually mediated behaviours of aquatic organisms, particularly fish. The Avon-Heathcote estuary of Christchurch, New Zealand, is one such body of water that is subject to tremendous variation in turbidity, no doubt exacerbated by the destruction of Christchurch in the 2010 and 2011 earthquakes, as well as the subsequent ongoing rebuild. The yellow eyed mullet, Aldrichetta Forsteri, is one species that is common with the estuary, and uses it as a habitat for breeding. Though very common throughout New Zealand, and even a part of the catch of commercial fisheries, the yellow eyed mullet is a largely unstudied organism, with virtually no published scientific enquiry based on the species. The present work assesses how several behaviours of the yellow eyed mullet are effected by acute turbidity at 10, 50, 90, 130 and 170 NTU, finding that: 1) The optomotor response of mullet to 2.5 mm stripes drops to insignificant levels between 10 and 50 NTU, 2) The swimming activity of the yellow eyed mullet is highest at 10 NTU and drops to a significantly lower level at higher turbidities, 3) The grouping behaviour of small groups of yellow eyed mullet are unchanged by increasing turbidity levels, 4) that yellow eyed mullet do not exhibit significantly different behavioural response to a simulated predator at any of the tested turbidities, and 5) that yellow eyed mullet to do significantly alter their oxygen consumption during exposure to the turbidities in an increasing series. The results presented in these studies indicate that turbidites above 50 NTU pose a significant risk to the lifestyle of the yellow eyed mullet, potentially impacting their ability to perceive their surroundings, feed, school, and avoid predation. Future work has a lot of ground to cover to more precisely determine the relationship between yellow eyed mullet behaviour and physiology, and the turbidity of their environment. In particular, future work should focus more closely on the turbidities between 10 and 50 NTU, as well as looking to field work to see what the predominant predators of the mullet are, and specifically whether turbidity increases or decreases the risk of mullet being subject to avian predation. There is also considerable scope for studies on the effects of chronic turbidity upon mullet, which will add understand to the predicament of escalating turbidity and its effects upon this common and yet mysterious native fish.

Research papers, University of Canterbury Library

A one story, two bays, approximately half scaled, perimeter moment frame containing precastprestressed floor units was built and tested at the University of Canterbury to investigate the effect of precastprestressed floor units on the seismic performance of reinforced concrete moment resisting frame. This paper gives an overview of the experimental set up and summarizes the results obtained from the test. The results show that elongation in the beam plastic hinges is partially restrained by the prestressed floor, which increases the strength of the beams much more than that being specified in the codes around the world.

Research papers, University of Canterbury Library

This thesis is concerned with the effects of lateral confining reinforcement on the ductile behaviour of reinforced concrete columns. The contents of the chapters are summarized as follows. In Chapter one, the general problems in seismic design are discussed and earthquake design methods based on the ductile design approach are described. Japanese, New Zealand and United States design codes are compared. Finally, the scope of this research project is outlined. In Chapter two, after reviewing previous research on confined concrete, the factors which affect the effectiveness of lateral confinement are discussed. Especially the effects of the yield strength of transverse reinforcement, the compressive strength of plain concrete and the strain gradient in the column section due to bending are discussed based on tests which were conducted by the author et al at Kyoto University and Akashi Technological College, Japan. In the axial compression tests on spirally reinforced concrete cylinders (150 mm in diameter by 300 mm in height), the yield strength of transverse reinforcement and the compressive strength of plain concrete were varied from 161 MPa to 1352 MPa and from 17 MPa to 60 MPa, respectively, as experimental parameters. It is found that, when high strength spirals are used as confining reinforcement, the strength and ductility of the confined core concrete are remarkably enhanced but need to be estimated assuming several failure modes which could occur. These are based on the observations that concrete cylinders with high strength spirals suddenly failed at a concrete compressive strain of 2 to 3.5 % due to explosive crushing of the core concrete between the spiral bars or due to bearing failure of the core concrete immediately beneath the spiral bars, while the concrete cylinders with ordinary strength spirals failed in a gentle manner normally observed. In addition, eccentric loading tests were conducted on concrete columns with 200 mm square section confined by square spirals. It is found that the effectiveness of confining reinforcement is reduced by the presence of the strain gradient along the transverse section of column. In Chapter three, the effectiveness of transverse reinforcement with various types of anchorage details which simplify the fabrication of reinforcing cages are investigated. Eight reinforced concrete columns, with either 400 mm or 550 mm square cross sections, were tested subjected to axial compression loading and cyclic lateral loading which simulated a severe earthquake. The transverse reinforcement consisted of arrangements of square perimeter hoops with 135° end hooks, cross ties with 90° and 135° or 180° end hooks, and 'U' and 'J' shaped cross ties and perimeter hoops with tension splices. Conclusions are reached with regard to the effectiveness of the tested anchorage details in the plastic hinge regions of columns designed for earthquake resistance. In Chapter four, the effectiveness of interlocking spirals as transverse reinforcement is studied. Firstly, the general aspects and the related problems of interlocking spirals to provide adequate ductility in the potential plastic hinge region of columns are discussed, referring to the provisions in the New Zealand code,the CALTRANS (California Transportation Authority) code and other related codes. Secondly, based on those discussions, a design method to securely interlock the spirals is proposed. Thirdly, the effectiveness of interlocking spirals is assessed based on column tests conducted as part of this study. Three columns with interlocking spirals and, for comparison, one rectangular column with rectangular hoopsandcross ties, were tested under cyclic horizontal loading which simulated a severe earthquake. The sections of those columns were 400 mm by 600 mm. In Chapter five, analytical models to investigate the buckling behaviour of longitudinal reinforcement restrained by cross ties with 90° and 135° end hooks and by peripheral hoops are proposed. The analyzed results using the proposed models compare well with the experimental observations described in Chapter three. Using those proposed models, a method to check the effectiveness of cross ties with 90° and 135° end hooks is proposed for practical design purposes. In Chapter six, a theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture referred to as the "Energy Balance Theory", which has been developed by Mander, Priestley and Park at University of Canterbury, is introduced. After discussing the problems in the "Energy Balance Theory", a modified theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture is proposed. The predictions from the modified theory are found to compare well with previous experimental results.

Research papers, University of Canterbury Library

This report describes in-plane experimental testing and numerical modelling of timberconcrete floor diaphragms. The experimental tests investigated the in-plane stiffness of the diaphragm and the stiffness and strength of different connections between the diaphragm and the lateral load resisting system. The test model was 1/3 scale and three meters square in plan. Seven tests with a different kind of connection between the floor and the rigid lateral supports (which simulated a timber lateral load resisting system) have been performed. The results of the experimental testing are used to calibrate numerical models which are used to investigate the effects of the floor flexibility on the seismic behaviour of post-tensioned timber buildings. For the experimental tests, screw and nail fasteners were used to connected to floor unit to the lateral supports. These fasteners were embedded into the concrete slab or timber edge joints at different orientations. The stiffness of the diaphragm connections was vastly different for each detail. Screws installed at a 45? angle (inclined) to the lateral supports were four times stiffer than the screws installed orthogonal to the lateral supports. The initial stiffness of the inclined fasteners was similar for timber-to-timber and concrete-to-timber connections. For the timberto- timber connections the orientation did not seem to influence the strength of the connection. The tested diaphragm had an uncracked stiffness of 4000 kN/mm and a cracked stiffness of 300 kN/mm. For the tested floor unit it was concluded that the influence of the diaphragm flexibility was negligible compared to the connector flexibility. The floor flexibility can be idealized as three different parts, the deformation of the connectors, the shear deformation of the diaphragm and the flexural deformation of the diaphragm. The numerical analyses showed that in most perceivable situations the connection deformation will govern the in-plane seismic response of the floor. Hence, it is justified to model it as a single-degree-of-freedom (SDOF) element. The influence of the floor flexibility on the seismic response of post-tensioned timber buildings is small. In most cases neglecting the floor flexibility is a conservative approach for the structural design of the building. However, structures with stiff walls and long floor spans there can be a significant amplification of the seismic response. For that case, a simple SDOF representation is proposed. Code-based recommendations for predicting the peak floor accelerations are found to be inadequate. A methodology is proposed to more accurately predict the expected peak floor accelerations for design

Research papers, University of Canterbury Library

Five years on from the 2010-2011 Canterbury earthquakes, research has shown an increase in hyperarousal symptoms in school children. While Cognitive Behaviour Therapy is currently the gold standard for treating Post-Traumatic Stress, there are insufficient clinicians to treat the high numbers of children in post-disaster communities. Alternative non-verbal interventions in school based settings that target the physiological basis of hyperarousal may be more effective for long term stress reduction in some young children. Neuroscience research suggests that drawing activates brain areas connected with the autonomic nervous system, resulting in relaxation and self-regulation. The aim of the current study was to determine whether a 20-minute drawing lesson during the afternoon of the school day would reduce stress in children with hyperarousal symptoms. The study had a single subject ABA design. Four children participated, two of the children exhibited hyperarousal symptoms, and the other two did not, as determined by teacher and parent responses on the Behaviour Problem Index (BPI). The children’s selfreported stress (measured by the Subjective Unit of Distress (SUD) thermometer) and physiological stress (measured by finger temperature) were recorded at the start and end of each session during baseline, drawing lessons, and return to baseline phases. The results of the study showed a general reduction in physiological stress during the drawing lessons for the children with hyperarousal symptoms. However, the results indicated some discrepancies between the children’s physiological stress and perception of stress, which may suggest that the self-report measure was inappropriate for the children in this study. Overall, the study suggests that drawing lessons show promise as a school-based intervention for reducing stress in children with hyperarousal. More research is required to address the limitations of the present study, and before the study can be applied to the whole classroom as a positive strategy for managing stress at school.

Research papers, University of Canterbury Library

Over the last six years, Canterbury residents have lived through two major earthquakes and thousands of aftershocks, with such events negatively impacting psychological health. Research shows rates of post-traumatic stress symptoms in children have doubled post-quake, and a classroom containing children who are experiencing chronically high physiological arousal has been shown to be a stressful environment for teachers. Such stress therefore negatively impacts teachers’ ability to sleep well, meaning many Christchurch teachers may suffer from insomnia, a debilitating condition leading to psychological distress and often comorbid with other mental health conditions. The present research sought to investigate the use of a broadspectrum micronutrient formula called EMPowerplus (EMP+) for chronic insomnia in teachers. This study examined the effect of EMP+ over an 8-10 week period using a multiple-baseline design with placebo. Seventeen teachers were randomized to one of three baseline sequences where they completed a one week baseline period, before receiving five, nine, or 14 days, of placebo as well as 8-10 weeks of the micronutrient formula. After completion of the trial, a three-month follow up was conducted. All participants completed the trial, and results showed a statistically reliable and clinically significant decrease in insomnia severity (Cohen’s dav = - 1.37), on at least one or more aspects of the sleep diary, and on emotional exhaustion (Cohen’s dav = -1.08). EMP+ also statistically significantly reduced insomnia severity compared to placebo (Cohen’s dav = -0.66). Statistically significant reduction was not seen in stress, anxiety and depression scores as compared to placebo, and these levels were not generally clinically raised to begin with. Sixteen out of 17 participants were compliant, and side effects were generally mild and transitory. The current study provides evidence for the beneficial effect of micronutrient supplementation on chronic insomnia in Christchurch teachers working in a stressful environment. Future research incorporating measurement of nutritional intake and proinflammatory biomarkers, as well as conducting comparisons to other conventional treatments, is recommended.