Design of light gauge steel roofing systems subject to high wind forces

Light gauge steel roofing systems made of thin profiled roof sheeting and battens are used commonly in residential, industrial and commercial buildings. Their critical design load combination is that due to wind uplift forces that occur during high wind events such as tropical cyclones and thunderstorms. However, premature local failures at their screw connections have been a concern for many decades since cyclone Tracy that devastated Darwin in 1974. Extensive research that followed cyclone Tracy on the pull-through and pull-out failures of roof sheeting to batten connections has significantly improved the safety of roof sheeting. However, this has made the batten to rafter/truss connection the weakest, and recent wind damage investigations have shown the failures of these connections and the resulting loss of entire roof structures. Therefore an experimental research program using both small scale and full scale air-box tests is currently under way to investigate the pull-through failures of thin-walled steel battens under high wind uplift forces. Tests have demonstrated that occurrence of pull-through failures in the bottom flanges of steel batttens and the need to develop simple test and design methods as a function of many critical parameters such as steel batten geometry, thickness and grade, screw fastener sizes and other fastening details. This paper presents the details of local failures that occur in light fauge roofing systems, a review of the current design and test methods for steel battens and associated short comings, and the test results obtained to date on pull-through failures of battens from small scale and full scale tests. Finally, it proposes the use of suitable small scale test methods that can be used by both researchers and manufacturers of such screw-fastened light gauge steel batten systems.

Intimate Drowning

intimate drowning 50 minute performance + installation work ice | salt | tears | This work is about death. Grief The relationships before The aftermath - of confusion, violence, isolation The never ending questions The devastating loss and paranoia "Since my wife died, I have spent the last six years treading water - trying to stop myself from drowning. Sometimes I catch myself not breathing. I have to remind myself that I can't live underwater no matter how much I want to." Grief. Loss. Tears. Fear. Sadness Water. Milk. Salt. Ice Falling. Waiting Submerged. Suffocated. Broken ties Intention. Lack of focus. Intensity of focus Fighting. Screaming. Wailing Blue. White. Black. Blackness The doors open: we walk through a gauze curtain and discover a dark space with a square of light in the middle of the room. As we walk closer to the light, we see a girl writing in charcoal on the floor around a square box filled with milk. She is writing the same thing over and over. The more she writes the more desperate she becomes: I am listening… We have to keep walking past. She isn’t writing for us. We find our seats Two people: one slowly breaking the hundreds of fragile strings that tie her to the other. The other is pleading with her to stop: Please. Please don’t. Please Avril. …Please don’t One girl facing away from us. She is slowly swimming on the spot without water. Projected next to her are images of her drowning under water. Salt falls in front of her. Behind her. A wall of salt. She is bound to the spot. Underwater and still breathing. Swimming in her own tears. She won’t escape. She wants to stay, but desires nothing Two people standing in a large square box filled with milk. They start in intimacy. The relationship begins to dissolve before us. One fights to be with/on/behind the other. The other fights her off. The milk is splashed. Why aren't they being careful? In the darkness there is scrubbing. Someone is scrubbing the floor. The other girl is on her knees trying to erase the original writing. The traces left behind that we have no control over. We only see her for a second, but hear her in the darkness. Scrubbing. It is pointless. You can't erase the past.

Experimental study of the mechanical properties of light gauge cold-formed steels at elevated temperatures

In recent times, light gauge cold-formed steel sections have been used extensively as primary load bearing structural members in many applications in the building industry. Fire safety design of structures using such sections has therefore become more important. Deterioration of mechanical properties of yield stress and elasticity modulus is considered the most important factor affecting the performance of steel structures in fires. Hence there is a need to fully understand the mechanical properties of light gauge cold-formed steels at elevated temperatures. A research project based on experimental studies was therefore undertaken to investigate the deterioration of mechanical properties of light gauge cold-formed steels. Tensile coupon tests were undertaken to determine the mechanical properties of these steels made of both low and high strength steels and thicknesses of 0.60, 0.80 and 0.95 mm at temperatures ranging from 20 to 800ºC. Test results showed that the currently available reduction factors are unsafe to use in the fire safety design of cold-formed steel structures. Therefore new predictive equations were developed for the mechanical properties of yield strength and elasticity modulus at elevated temperatures. This paper presents the details of the experimental study, and the results including the developed equations. It also includes details of a stress-strain model for light gauge cold-formed steels at elevated temperatures.

Structural and fire behaviour of a new light gauge steel wall system

Fire design is an essential element of the overall design procedure of structural steel members and systems. Conventionally the fire rating of load-bearing stud wall systems made of light gauge steel frames (LSF) is based on approximate prescriptive methods developed on the basis of limited fire tests. This design is limited to standard wall configurations used by the industry. Increased fire rating is provided simply by adding more plasterboards to the stud walls. This is not an acceptable situation as it not only inhibits innovation and structural and cost efficiencies but also casts doubt over the fire safety of these light gauge steel stud wall systems. Hence a detailed fire research study into the performance and effectiveness of a recently developed innovative composite panel wall system was undertaken at Queensland University of Technology using both full scale fire tests and numerical studies. Experimental results of LSF walls using the new composite panels under axial compression load have shown the improvement in fire performance and fire resistance rating. Numerical analyses are currently being undertaken using the finite element program ABAQUS. Measured temperature profiles of the studs are used in the numerical models and the results are used to calibrate against full scale test results. The validated model will be used in a detailed parametric study with an aim to develop suitable design rules within the current cold-formed steel structures and fire design standards. This paper will present the results of experimental and numerical investigations into the structural and fire behaviour of light gauge steel stud walls protected by the new composite panel. It will demonstrate the improvements provided by the new composite panel system in comparison to traditional wall systems.

Improvements to the fire performance of light gauge steel floor systems

Light gauge steel frame (LSF) structures are increasingly used in commercial and residential buildings because of their non-combustibility, dimensional stability and ease of installation. A common application is in floor-ceiling systems. The LSF floor-ceiling systems must be designed to serve as fire compartment boundaries and provide adequate fire resistance. Fire-rated floor-ceiling assemblies have been increasingly used in buildings. However, limited research has been undertaken in the past and hence a thorough understanding of their fire resistance behaviour is not available. Recently a new composite floor-ceiling system has been developed to provide higher fire rating. But its increased fire rating could not be determined using the currently available design methods. Therefore a research project was conducted to investigate its structural and fire resistance behaviour under standard fire conditions. This paper presents the results of full scale experimental investigations into the structural and fire behaviour of the new LSF floor system protected by the composite ceiling unit. Both the conventional and the new floor systems were tested under structural and fire loads. It demonstrates the improvements provided by the new composite panel system in comparison to conventional floor systems. Numerical studies were also undertaken using the finite element program ABAQUS. Measured temperature profiles of floors were used in the numerical analyses and their results were compared with fire test results. Tests and numerical studies provided a good understanding of the fire behaviour of the LSF floor-ceiling systems and confirmed the superior performance of the new composite system.

Theoretical comparison of innovative window daylighting devices for a sub-tropical climate using radiance

Daylighting in tropical and sub-tropical climates presents a unique challenge that is generally not well understood by designers. In a sub-tropical region such as Brisbane, Australia the majority of the year comprises of sunny clear skies with few overcast days and as a consequence windows can easily become sources of overheating and glare. The main strategy in dealing with this issue is extensive shading on windows. However, this in turn prevents daylight penetration into buildings often causing an interior to appear gloomy and dark even though there is more than sufficient daylight available. As a result electric lighting is the main source of light, even during the day. Innovative daylight devices which redirect light from windows offer a potential solution to this issue. These devices can potentially improve daylighting in buildings by increasing the illumination within the environment decreasing the high contrast between the window and work regions and deflecting potentially glare causing sunlight away from the observer. However, the performance of such innovative daylighting devices are generally quantified under overcast skies (i.e. daylight factors) or skies without sun, which are typical of European climates and are misleading when considering these devices for tropical or sub-tropical climates. This study sought to compare four innovative window daylighting devices in RADIANCE; light shelves, laser cut panels, micro-light guides and light redirecting blinds. These devices were simulated in RADIANCE under sub-tropical skies (for Brisbane) within the test case of a typical CBD office space. For each device the quantity of light redirected and its distribution within the space was used as the basis for comparison. In addition, glare analysis on each device was conducted using Weinold and Christoffersons evalglare. The analysis was conducted for selected hours for a day in each season. The majority of buildings that humans will occupy in their lifetime are already constructed, and extensive remodelling of most of these buildings is unlikely. Therefore the most effective way to improve daylighting in the near future will be through the alteration existing window spaces. Thus it will be important to understand the performance of daylighting systems with respect to the climate it is to be used in. This type of analysis is important to determine the applicability of a daylighting strategy so that designers can achieve energy efficiency as well the health benefits of natural daylight.

Test and evaluation of non conventional instrument transformers and sampled value process bus on Powerlink's transmission network

IEC 61850 Process Bus technology has the potential to improve cost, performance and reliability of substation design. Substantial costs associated with copper wiring (designing, documentation, construction, commissioning and troubleshooting) can be reduced with the application of digital Process Bus technology, especially those based upon international standards. An IEC 61850-9-2 based sampled value Process Bus is an enabling technology for the application of Non-Conventional Instrument Transformers (NCIT). Retaining the output of the NCIT in its native digital form, rather than conversion to an analogue output, allows for improved transient performance, dynamic range, safety, reliability and reduced cost. In this paper we report on a pilot installation using NCITs communicating across a switched Ethernet network using the UCAIug Implementation Guideline for IEC 61850-9-2 (9-2 Light Edition or 9-2LE). This system was commissioned in a 275 kV Line Reactor bay at Powerlink Queensland’s Braemar substation in 2009, with sampled value protection IEDs 'shadowing' the existing protection system. The results of commissioning tests and twelve months of service experience using a Fibre Optic Current Transformer (FOCT) from Smart Digital Optics (SDO) are presented, including the response of the system to fault conditions. A number of remaining issues to be resolved to enable wide-scale deployment of NCITs and IEC 61850-9-2 Process Bus technology are also discussed.

Examining the black box between stimulating regions and individual entrepreneurship

This paper seeks to investigate the link between the objective regional opportunity structure (captured by regional data) and individuals’ engagement in different stages in the venture creation process (intention to start a business and engagement in nascent entrepreneurship). We further investigate pathways through which a favourable regional environment could affect entrepreneurial intentions and the propensity to be a nascent entrepreneur. We combine individual level GEM-data for Western Germany with regional level data from the statistical office and use multi-level analysis to test our hypotheses. We find support for our contention that a favourable regional opportunity structure affects entrepreneurial intentions and engagement. As pathways between the region and individual behaviour serve the individual perception of founding opportunities and the individual social capital.

“More tick-the-box”: the challenge of promoting interdisciplinary learning in the middle years through the Australian history curriculum

The Australian Curriculum marks national reforms in social science education, first with the return to the disciplines of history and geography and second, through a new approach to interdisciplinary learning. This paper raises the question of whether the promise of interdisciplinary learning can be realised in the middle years of schooling if teachers have to teach history as a discipline rather than within an over-arching integrated curriculum framework. The paper explores the national blueprints and considers the national history curriculum in light of theories of teachers’ knowledge and middle school education. Evidence from teacher interviews indicates that historical understanding can be achieved through integrated frameworks to meet the goals of middle schooling.

Characterisation of the TaNF-Y family of transcription factors in wheat

Light plays a unique role for plants as it is both a source of energy for growth and a signal for development. Light captured by the pigments in the light harvesting complexes is used to drive the synthesis of the chemical energy required for carbon assimilation. The light perceived by photoreceptors activates effectors, such as transcription factors (TFs), which modulate the expression of light-responsive genes. Recently, it has been speculated that increasing the photosynthetic rate could further improve the yield potential of three carbon (C3) crops such as wheat. However, little is currently known about the transcriptional regulation of photosynthesis genes, particularly in crop species. Nuclear factor Y (NF-Y) TF is a functionally diverse regulator of growth and development in the model plant species, with demonstrated roles in embryo development, stress response, flowering time and chloroplast biogenesis. Furthermore, a light-responsive NF-Y binding site (CCAAT-box) is present in the promoter of a spinach photosynthesis gene. As photosynthesis genes are co-regulated by light and co-regulated genes typically have similar regulatory elements in their promoters, it seems likely that other photosynthesis genes would also have light-responsive CCAAT-boxes. This provided the impetus to investigate the NF-Y TF in bread wheat. This thesis is focussed on wheat NF-Y members that have roles in light-mediated gene regulation with an emphasis on their involvement in the regulation of photosynthesis genes. NF-Y is a heterotrimeric complex, comprised of the three subunits NF-YA, NF-YB and NF-YC. Unlike the mammalian and yeast counterparts, each of the three subunits is encoded by multiple genes in Arabidopsis. The initial step taken in this study was the identification of the wheat NF-Y family (Chapter 3). A search of the current wheat nucleotide sequence databases identified 37 NF-Y genes (10 NF-YA, 11 NF-YB, 14 NF-YC & 2 Dr1). Phylogenetic analysis revealed that each of the three wheat NF-Y (TaNF-Y) subunit families could be divided into 4-5 clades based on their conserved core regions. Outside of the core regions, eleven motifs were identified to be conserved between Arabidopsis, rice and wheat NF-Y subunit members. The expression profiles of TaNF-Y genes were constructed using quantitative real-time polymerase chain reaction (RT-PCR). Some TaNF-Y subunit members had little variation in their transcript levels among the organs, while others displayed organ-predominant expression profiles, including those expressed mainly in the photosynthetic organs. To investigate their potential role in light-mediated gene regulation, the light responsiveness of the TaNF-Y genes were examined (Chapters 4 and 5). Two TaNF-YB and five TaNF-YC members were markedly upregulated by light in both the wheat leaves and seedling shoots. To identify the potential target genes of the light-upregulated NF-Y subunit members, a gene expression correlation analysis was conducted using publically available Affymetrix Wheat Genome Array datasets. This analysis revealed that the transcript expression levels of TaNF-YB3 and TaNF-YC11 were significantly correlated with those of photosynthesis genes. These correlated express profiles were also observed in the quantitative RT-PCR dataset from wheat plants grown under light and dark conditions. Sequence analysis of the promoters of these wheat photosynthesis genes revealed that they were enriched with potential NF-Y binding sites (CCAAT-box). The potential role of TaNF-YB3 in the regulation of photosynthetic genes was further investigated using a transgenic approach (Chapter 5). Transgenic wheat lines constitutively expressing TaNF-YB3 were found to have significantly increased expression levels of photosynthesis genes, including those encoding light harvesting chlorophyll a/b-binding proteins, photosystem I reaction centre subunits, a chloroplast ATP synthase subunit and glutamyl-tRNA reductase (GluTR). GluTR is a rate-limiting enzyme in the chlorophyll biosynthesis pathway. In association with the increased expression of the photosynthesis genes, the transgenic lines had a higher leaf chlorophyll content, increased photosynthetic rate and had a more rapid early growth rate compared to the wild-type wheat. In addition to its role in the regulation of photosynthesis genes, TaNF-YB3 overexpression lines flower on average 2-days earlier than the wild-type (Chapter 6). Quantitative RT-PCR analysis showed that there was a 13-fold increase in the expression level of the floral integrator, TaFT. The transcript levels of other downstream genes (TaFT2 and TaVRN1) were also increased in the transgenic lines. Furthermore, the transcript levels of TaNF-YB3 were significantly correlated with those of constans (CO), constans-like (COL) and timing of chlorophyll a/b-binding (CAB) expression 1 [TOC1; (CCT)] domain-containing proteins known to be involved in the regulation of flowering time. To summarise the key findings of this study, 37 NF-Y genes were identified in the crop species wheat. An in depth analysis of TaNF-Y gene expression profiles revealed that the potential role of some light-upregulated members was in the regulation of photosynthetic genes. The involvement of TaNF-YB3 in the regulation of photosynthesis genes was supported by data obtained from transgenic wheat lines with increased constitutive expression of TaNF-YB3. The overexpression of TaNF-YB3 in the transgenic lines revealed this NF-YB member is also involved in the fine-tuning of flowering time. These data suggest that the NF-Y TF plays an important role in light-mediated gene regulation in wheat.

‘Spotty Dick’ : a research experiment to test design suitability for the use of jewelled spot matrix patterns for UV aware men’s swimwear

The great male Aussie cossie is growing spots. The ‘dick’ tog, as it is colloquially referred to, is linked to Australia’s national identify with overtly masculine bronzed Aussie bodies clothed in this iconic apparel. Yet the reality is our hunger for worshiping the sun and the addiction to a beach lifestyle is tempered by the pragmatic need for neck-to-knee, or more apt head-to-toe, swimwear. Spotty Dick is an irreverent play on male swimwear – it experiments with alternate modes to sheath the body with Lyrca in order to protect it from searing UV’s and at the same time light-heartedly fools around with texture and pattern; to be specific, black Scharovsky crystals, jewelled in spot patterns - jewelled clothing is not characteristically aligned to menswear and even less so to the great Aussie cossie. The crystals form a matrix of spots that attempt to provoke a sense of mischievousness aligned to the Aussie beach larrikin. Ironically, spot patterns are in itself a form of a parody, as prolonged sun exposure ages the skin and sun spots can occur if appropriate sun protection is not used. ‘Spotty Dick’ – a research experiment to test design suitability for the use of jewelled spot matrix patterns for UV aware men’s swimwear. The creative work was paraded at 56 shows, over a 2 week period, and an estimated 50,000 people viewed the work.

Face recognition across pose on video using eigen light-fields

We propose an approach to employ eigen light-fields for face recognition across pose on video. Faces of a subject are collected from video frames and combined based on the pose to obtain a set of probe light-fields. These probe data are then projected to the principal subspace of the eigen light-fields within which the classification takes place. We modify the original light-field projection and found that it is more robust in the proposed system. Evaluation on VidTIMIT dataset has demonstrated that the eigen light-fields method is able to take advantage of multiple observations contained in the video.

Numerical modelling of non-load bearing light gauge cold-formed steel frame walls under fire conditions

Recently an innovative composite panel system was developed, where a thin insulation layer was used externally between two plasterboards to improve the fire performance of light gauge cold-formed steel frame walls. In this research, finite-element thermal models of both the traditional light gauge cold-formed steel frame wall panels with cavity insulation and the new light gauge cold-formed steel frame composite wall panels were developed to simulate their thermal behaviour under standard and realistic fire conditions. Suitable apparent thermal properties of gypsum plasterboard, insulation materials and steel were proposed and used. The developed models were then validated by comparing their results with available fire test results. This article presents the details of the developed finite-element models of small-scale non-load-bearing light gauge cold-formed steel frame wall panels and the results of the thermal analysis. It has been shown that accurate finite-element models can be used to simulate the thermal behaviour of small-scale light gauge cold-formed steel frame walls with varying configurations of insulations and plasterboards. The numerical results show that the use of cavity insulation was detrimental to the fire rating of light gauge cold-formed steel frame walls, while the use of external insulation offered superior thermal protection to them. The effects of real fire conditions are also presented.

Dynamics of rod and cone photoreceptor interactions under mesopic light levels

Visual adaptation regulates contrast sensitivity during dynamically changing light conditions (Crawford, 1947; Hecht, Haig & Chase, 1937). These adaptation dynamics are unknown under dim (mesopic) light levels when the rod (R) and long (L), medium (M) and short (S) wavelength cone photoreceptor classes contribute to vision via interactions in shared non-opponent Magnocellular (MC), chromatically opponent Parvocellular (PC) and Koniocellular (KC) visual pathways (Dacey, 2000). This study investigated the time-course of adaptation and post-receptoral pathways mediating receptor specific rod and cone interactions under mesopic illumination. A four-primary photostimulator (Pokorny, Smithson & Quinlan, 2004) was used to independently control the activity of the four photoreceptor classes and their post-receptoral visual athways in human observers. In the first experiment, the contrast sensitivity and time-course of visual adaptation under mesopic illumination were measured for receptoral (L, S, R) and post-receptoral (LMS, LMSR, L-M) stimuli. An incremental (Rapid-ON) sawtooth conditioning pulse biased detection to ON-cells within the visual pathways and sensitivity was assayed relative to pulse onset using a briefly presented incremental probe that did not alter adaptation. Cone.Cone interactions with luminance stimuli (L cone, LMS, LMSR) reduced sensitivity by 15% and the time course of recovery was 25± 5ms-1 (μ ± SEM). PC mediated (+L-M) chromatic stimuli sensitivity loss was less (8%) than for luminance and recovery was slower (μ = 2.95 ± 0.05 ms-1), with KC mediated (S cone) chromatic stimuli showing a high sensitivity loss (38%) and the slowest recovery time (1.6 ± 0.2 ms-1). Rod-Rod interactions increased sensitivity by 20% and the time course of recovery was 0.7 ± 0.2 ms-1 (μ ± SD). Compared to these interaction types, Rod-Cone interactions reduced sensitivity to a lesser degree (5%) and showed the fastest recovery (μ = 43 ± 7 ms-1). In the second experiment, rod contribution to the magnocellular, parvocellular and koniocellular post-receptoral pathways under mesopic illumination was determined as a function of incremental stimulus duration and waveform (rectangular; sawtooth) using a rod colour match procedure (Cao, Pokorny & Smith, 2005; Cao, Pokorny, Smith & Zele, 2008a). For a 30% rod increment, a cone match required a decrease in [L/(L+M)] and an increase in [L+M] and [S/(L+M)], giving a greenish-blue and brighter appearance for probe durations of 75 ms or longer. Probe durations less than 75 ms showed an increase in [L+M] and no change in chromaticity [L/(L+M) or S/(L+M)], uggesting mediation by the MC pathway only for short duration rod stimuli. s We advance previous studies by determining the time-course and nature of photoreceptor specific retinal interactions in the three post-receptoral pathways under mesopic illumination. In the first experiment, the time-course of adaptation for ON cell processing was determined, revealing opponent cell facilitation in chromatic PC and KC pathways. The Rod-Rod and Rod-Cone data identify previously unknown interaction types that act to maintain contrast sensitivity during dynamically changing light conditions and improve the speed of light adaptation under mesopic light levels. The second experiment determined the degree of rod contribution to the inferred post-eceptoral pathways as a function of the temporal properties of the rod signal. r The understanding of the mechanisms underlying interactions between photoreceptors under mesopic illumination has implications for the study of retinal disease. Visual function has been shown to be reduced in persons with age-related maculopathy (ARM) risk genotypes prior to clinical signs of the disease (Feigl, Cao, Morris & Zele, 2011) and disturbances in rod-mediated adaptation have been shown in early phases of ARM (Dimitrov, Guymer, Zele, Anderson & Vingrys, 2008; Feigl, Brown, Lovie-Kitchin & Swann, 2005). Also, the understanding of retinal networks controlling vision enables the development of international lighting standards to optimise visual performance nder dim light levels (e.g. work-place environments, transportation).

"More tick-the-box": the challenge of promoting interdisciplinary learning in the middle years through the Australian history curriculum

The Australian Curriculum marks national reforms in social science education, first with the return to the disciplines of history and geography and second, through a new approach to interdisciplinary learning. This paper raises the question of whether the promise of interdisciplinary learning can be realised in the middle years of schooling if teachers have to teach history as a discipline rather than within an over-arching integrated curriculum framework. The paper explores the national blueprints and considers the national history curriculum in light of theories of teachers’ knowledge and middle school education. Evidence from teacher interviews indicates that historical understanding can be achieved through integrated frameworks to meet the goals of middle schooling.