Structures In Australia Research Articles

Dynamic Performance of a Brick Veneer House with Steel Framing

Brick veneer construction is a very common form for residential structures in Australia and is growing in popularity in New Zealand. The structural frame is made from steel or timber, and non-structural brick walls are attached to the frame via brick ties. Under earthquake loading there is a complex interaction between the frame and veneer walls, particularly in the out- of-plane direction, where there is risk of brick wall collapse. While there is a standard component test method for assessing the seismic capacity of brick ties, this method has been developed around brick veneer on timber studs. In order to realistically assess the overall performance of brick veneer construction with steel framing, a full scale one-room test structure “Test House” was tested on a shaking table. The Test House incorporated veneer walls with different geometries. It was subjected to varying levels of the El-Centro earthquake ranging from moderate serviceability limit state ground motion to well beyond the design maximum considered earthquake for New Zealand. These levels of shaking were selected in order to ascertain the response for specific limit states to the New Zealand Loading Standard and to compare against minimum performance requirements. Comprehensive measurements on the frame and veneer walls were taken, including acceleration, drift and differential movements between the frame and veneer. The Test House performed very well, with no brick loss up to 2.6 times El-Centro earthquake, which is well in excess of all performance requirements. This paper presents a summary of the outcomes from the experimental test program.

Experimental Investigation of High Strength Cold-Formed C-Sections in Combined Bending and Shear

In roof systems, a high strength steel profiled sheeting fastened to high strength steel cold-formed purlins of a lipped C- or Z-section is commonly used throughout the world. The design of such systems is performed according to the provisions of the limit states Australia/New Zealand Standard for Cold-Formed Steel Structures in Australia and the North American Specification for the Design of Cold-Formed Steel Structural Members in the United States. In both standards, which include the newly developed direct strength method of design (DSM), the method presented is limited to pure compression and pure bending. The situations of pure shear and combined bending and shear as occurs in a continuous purlin system are not considered. In order to extend the DSM to purlin systems, three different test series on high strength cold-formed C-section purlins have been performed at the University of Sydney. The test series include predominantly shear, combined bending and shear, and bending only test series. Two different section depths and three different thicknesses of the lipped channel section were tested in this study. Further, tests with and without torsion/distortion restraint straps screwed on the top flanges adjacent to the loading points were also considered. This paper summarizes the test results and formulas developed from the effective width method and the DSM. Proposals for design are included in this paper. Comparisons with the Australian Steel Structures Standard are also included to take account of the tension field action.

Genetic and behavioural evidence for a city‐wide supercolony of the invasive Argentine ant Linepithema humile (Mayr) (Hymenoptera: Formicidae) in southeastern Australia

AbstractThe success of invasive ants is frequently attributed to genetic and behavioural shifts in colony structure during or after introduction. The Argentine ant (Linepithema humile), a global invader, differs in colony genetic structure and behaviour between native populations in South America and introduced populations in Europe, Japan, New Zealand and North America. However, little is known about its colony structure in Australia. We investigated the genetic structure and behaviour of L. humile across Melbourne, Victoria by quantifying variation at four microsatellite loci and assaying intraspecific aggression at neighbourhood (30–200 m), fine (1–3.3 km) and regional (5–82 km) spatial scales. Hierarchical analyses across these scales revealed that most genetic variation occurred among workers within nests (∼98%). However, although low genetic differentiation occurred among workers between nests at the fine and regional scales (∼2%), negligible differentiation was detected among workers from neighbouring nests. Spatial genetic autocorrelation analysis confirmed that neighbouring nests were genetically more similar to each other. Lack of aggression within and across these scales supported the view that L. humile is unicolonial and forms a large supercolony across Melbourne. Comparisons of genetic structure of L. humile among single nests sampled from Adelaide, Brisbane, Hobart and Perth with Melbourne showed no greater levels of genetic differentiation or dissimilar spatial structure, suggesting an Australia‐wide supercolony.

Analysis, Design and Construction of Complex Concrete Structures for the Water Treatment Industry

The design and construction of concrete water treatment and storage structures in Australia has catered for the existing markets. The next generation of these structures needs a more sophisticated approach. Engineers who analyse and design water treatment plants, or water and liquid storage structures, as well as other complex reinforced and pre-stressed concrete structures, will find this paper of interest. Advanced water treatment plants and water factories for recycling domestic and industrial waste water have introduced new complexities into concrete tank design. Two recently constructed Australian water purifying plants provide examples of the theoretical and practical challenges of designing and constructing the large and complex process vessels required by modern plants to produce large volumes of high-quality water.

Skilled Immigration and Wages in Australia*

This paper investigates the impact of the relative growth of skilled migration on the structure of Australian wages. Unlike conventional approaches, the present study uses macro data to examine the response of wages to immigration flows. We use instrumental variable techniques to control for the potential endogeneity of immigration. The results, using alternative estimation strategies, are consistent with the dominant findings from existing empirical work. There is no robust evidence that a relative increase in skilled immigrants exerts any discernible adverse consequences on the wage structure in Australia.

Congruence between environmental parameters, morphology and genetic structure in Australia’s most widely distributed eucalypt, Eucalyptus camaldulensis

Eucalyptus camaldulensis is one of the most widely utilised eucalypts. It is also the only eucalypt that occurs across the Australian continent, playing a key ecological role as fauna habitat and in riverbank stabilisation. Despite its ecological and economic importance, uncertainty remains regarding the delineation of genetic and morphological variants. Nine hundred and ninety trees from 97 populations, representing the species’ geographic range were genotyped using 15 microsatellite loci and patterns of diversity compared with restriction fragment length polymorphisms in 29 of these populations. Both markers showed that despite having a riverine distribution, downstream seed dispersal has had less influence than geographic distance on dispersal patterns. Spatial patterns in the distribution of microsatellite genotypes were compared with environmental parameters and boundaries defined by river systems, drainage basins and proposed subspecies. Significant genetic differences among populations within river systems indicated that rivers should not be treated as a single genetic entity in conservation or breeding programmes. Strong geographic trends were evident with 40% of variation in genetic diversity explained by latitude and moisture index. Isolation by distance and significant correlations between genetic distance and environmental parameters for most loci suggest historical factors have had more influence than selection on current patterns of distribution of genetic diversity. Geographic structuring of molecular variation, together with congruence between genetic and morphological variation indicate that E. camaldulensis should be treated as a number of subspecies rather than a single variable taxon. High levels of genetic diversity and geographic trends in the distribution of variation provide a firm basis for further exploration of the species’ genetic resources.

Engineering for Earthquakes in Australia

The history of Australia’s large earthquakes and tectonic setting is summarised to impress on engineers the need for earthquake loads to be considered in the design and construction of structures in Australia. Special consideration should be given to retrofitting all existing schools and hospitals. The lack of Australian strong motion data leads to conservative loading factors and this will only be remedied when an appropriate accelerograph network is installed throughout the country, akin to the meteorological monitoring network.

Modern design, construction and maintenance of composite steelconcrete structures: Australian experiences

Modern design, construction innovation and maintenance issues have been extensively utilised for composite steel-concrete building structures in Australia. This paper provides an overview of the design codes, innovative construction applications and maintenance issues for steel-concrete composite members in Australia. The paper initially provides an overview of the various codes of practice for steel-concrete composite members in Australia. In identifying construction innovation significant projects to adopt composite construction techniques are considered. Many of these projects have found that the national codes of practice have been lacking in guidance. This has thus been the focal point for much of the research into the area of steel-concrete composite members over the last two decades. The paper concludes with research that is currently being carried out which considers materials and solutions in composite structural forms which promote the concepts of sustainability and will inevitably be prominent in improved maintenance of steel structures in the future.

The use of Characteristic Strengths in Masonry Design

SummaryDespite recent advances in our understanding of masonry behaviour, the design of masonry structures in Australia in accordance with AS 3700 is often problematic. The recommended methods of calculation and the relevant material properties do not produce designs commensurate with some common practices. These common practices have stood the test of time, but in some cases cannot be justified by present design methods. In this respect, Australian design standards are no different from their overseas counterparts. This paper examines the design approaches used by AS 3700for masonry bending and for wall ties. In particular, the use of characteristic strengths and their validity in terms of the models of behaviour are examined. Alternative approaches are proposed, which produce designs more commensurate with common practice and that, it is argued, more accurately represent the actual structural behaviour.

Calculation of Earthquake Actions on Building Structures in Australia

This paper presents from first principles methods of evaluating the seismic performance of a building using the method of inertial forces, method of maximum energy and method of maximum displacement. The introduction of these methods forms the main thrust of the paper. Importantly, the building can be deemed safe should this be indicated by any one of the three methods none of which requires the natural period of the building nor structural response factors to be estimated. Whilst these methods are verysimple and consume little time to apply, the accuracies of the results are comparable with those from response spectrum methods. It is noted that the fundamental basis of each of these methods is very consistent with the new response spectrum model stipulated by the new Australian standard for seismic actions. A succinct and insightful account of the development of the seismic hazard model for Australia is also provided followed by a commentary on the use of dynamic analysis methods in practice.

Emerging from the shadow of medicine: allied health as a ‘profession community’ subculture

The authority relationship between medicine and the allied health professions has been conceptualised as one of subordination. The research that underpinned the subordination thesis was largely based on pre-1980 studies of interprofessional interaction and struggle. This article presents data from a comparative longitudinal case study analysis of Australian allied health professions employed in three distinct organisational models in urban acute care general hospitals during the 1990s. The article discusses the emergence of a distinct allied health ‘profession community’ subculture associated with the emergence of new organisational structures in Australia. A model to account for subculture development under different organisational conditions is proposed. A key concern is the way in which a ‘profession community’ is created, structured and maintained in the complex organisational settings of the acutecare hospital. The findings challenge the notion that subordination is an inevitable consequence of medical dominance and calls for a re-formulation of our understanding of the relationship between medicine and allied health professions in light of contemporary health service reforms.

Comparison of fire patterns and fire frequency in two tropical savanna bioregions

Abstract Fire is a significant determinant of vegetation structure in Australia’s savannas and has been implicated in the decline of many species. Identifying the patterns of fire in the landscape is fundamental to understanding vegetation dynamics but variation over time and space makes generalization difficult and specific management recommendations elusive. In order to improve the knowledge base for fire management in tropical savannas, we investigated interregional variation in fire patterns in two Queensland bioregions, the Mount Isa Inlier (MII) and Cape York Peninsula (CYP), over a 5‐year period (1999–2003). Remotely sensed satellite data were used to identify burnt areas on a monthly basis for the western half of the CYP bioregion and about two‐thirds of the smaller MII. Fire scars were mapped from JPEG‐compressed, low‐resolution Landsat images using geographical information system technology and data were investigated to determine annual burning patterns. Patterns were interpreted with regard to meteorological information and recent fire history. The area burnt per annum on western CYP was generally an order of magnitude greater than the area burnt on the MII. In the biggest fire year, nearly 74% (5 295 098 ha) of the CYP landscape burnt, compared with 35% (1 770 771 ha) of the MII landscape. The minimum percentage of the CYP study area burnt in 1 year between 1999 and 2003 was 43.1%, compared with 1.6% for the MII. The reliability and amount of seasonal rainfall was a strong determinant of differences in time of fire occurrence and area burnt between regions. Widespread wildfires were significantly related to above average rainfall in the preceding 12 months in the Mt. Isa area but not in CYP. Rainfall also affected fire frequency. Predictable wet season rainfall on CYP allowed for a biennial fire return interval, while on the semiarid MII, the average fire return interval was 5 years or longer. We conclude that the fire patterns in the semiarid MII are similar to those reported for arid Australia, while fire patterns in western CYP are comparable with other mesic savanna areas.

Fibre composite structures in Australia's civil engineering market: an anatomy of innovation

AbstractDuring the last 5–10 years there has been considerable activity in research and development of fibre composites in the Australian civil engineering market. Areas of activity have included; bridge systems, replacement of large‐section hardwood girders, waterfront structures and railway sleepers. The work has involved not only the initial concept development, but also the construction and deployment of full‐scale prototypes. Through close involvement of major asset owners, including state road and rail authorities and city councils, these technologies have evolved from initial technology demonstrators to become viable commercial alternatives to traditional structural solutions. This paper presents a review of these developments and examines the process involved in taking these new systems from a novelty to a viable and credible alternative for local asset owners.

Enhancement of magnetic signatures of impact structures

Aeromagnetic surveys play an important role in the detection and analysis of terrestrial impact structures as large semi-regional aeromagnetic surveys are widely available. Impact craters can be divided into two groups based on morphostructure, namely simple and complex. Simple craters are relatively small bowl-shaped depressions with an upraised and fractured rim whereas complex craters are larger with a central uplift zone. Magnetic signatures of terrestrial impact craters vary greatly, reflecting the target rocks, the impact-related magnetisation and effects of crater fill and post-impact sediments. In basement rocks, the common signature is a magnetic low, ranging in amplitude from a few nT up to a few hundred nT. The central peak or ring uplift of crushed basement may produce strong magnetic highs. The magnetic signature may be due to shock demagnetisation, shock remagnetisation, and thermal and chemical remanent magnetisation effects. Impact craters in sedimentary targets are usually subdued and amplitudes of a few nT up to 10 nT are common. Enhancement of magnetic signatures of impact structures using filtering techniques is an important part of detection and analysis. Derivatives and shaded relief techniques, along with separation filtering, are probably the most used methods. Algorithms for fractional order derivatives and circular shaded relief have dramatically improved filter results. The fractional derivative order can be varied to optimise separation of the impact magnetic signature. Circular shaded relief treats all directions equally unlike the fade-out for features sub-parallel to the shading direction evident in conventional shading. The fractional order derivative and circular shaded relief algorithms are illustrated from impact structures in Australia and Canada in both basement and sedimentary cover rocks.

From efficacy to effectiveness: case studies in unemployment research.

There have been few attempts to implement and disseminate programmes to address the psychological health impact of unemployment despite the burden of this problem upon public health and health services. One approach that has demonstrated efficacy in promoting both psychological health and employment for this group is based upon the principles of cognitive behavioural therapy (CBT). We have been involved in three interventions based upon CBT to improve the psychological health of people who are unemployed, delivered through existing service structures in Australia: employment support agencies, general practice and mental health services. In this paper, we examine our experiences in conducting research within these service organizations using a framework for collaboration between researchers and services based upon intersectoral action. While effective collaboration can facilitate the implementation of research within systems, poor collaboration can impact upon the integrity of research designs. In our experience, it was the capacity of service organizations to address the psychological health impact of unemployment in particular that had a significant effect upon adoption of the intervention. Service organizations did not have structures to support the rigorous evaluation of interventions nor did they have funding arrangements that facilitated effective collaboration on research to address psychological issues. The dissemination of evidence-based interventions like CBT to populations of people who are unemployed in Australia is hindered by the absence of an accessible and appropriate system through which to address the psychological health impact of unemployment.

Agency costs and ownership structure in Australia

Financial economics often assumes that equity agency costs increase with the separation of ownership and control. This paper tests this relationship using a survey sample of approximately 3800 Australian small and medium enterprises for 1996–1997 and 1997–1998. Following Ang et al. [J. Finance 55 (2000) 81], we estimate a zero equity agency cost benchmark (in terms of operating expenses and asset utilization ratios) for the 100% owner-manager firm. We then examine how agency costs change when ownership and control are separated. We report a positive relationship between equity agency costs and the separation of ownership and control.

Australian Farm Inheritance—New Patterns of Legal Structure in Property Rights and Landholding

New circumstances in Australian agriculture require new legal arrangements for landholding and for people who have new aspirations for retirement and succession planning. A recent Australia-wide farm survey of landholding patterns creates space for consideration of these changing property concepts and relationships as they relate to inheritance patterns and the engagement of the next generation in farming. Early studies of land tenure predicted a gradual progression from tenant or share farmer to full owner as aspiring young farmers aged and became more involved in farming and raising a family. This pattern has come under scrutiny as corporate involvement in agriculture accelerates in Western societies. This paper investigates Australian family farmer intentions to pass farm assets on to chosen heirs so that the present family farming system continues intact. Survey data collected from a broader study of a variety of farming industries is used to tease out whether new patterns of legal structure in land and job inheritance are emerging. The findings indicate that different legal structures of property ownership are utilised as legitimate means of protecting farmer values concerned with property, family and inheritance. Further research on inheritance patterns and legal structure in Australia is indicated.

Flattening the Effective Marginal Tax Rate Structure in Australia: Policy Simulations Using the Melbourne Institute Tax and Transfer Simulator

AbstractThis article uses the Melbourne Institute Tax and Transfer Simulator to examine the effects of a reduction in the means‐tested benefit taper, or withdrawal, rates in Australia to 30 per cent. That is, all taper rates of 50 per cent and 70 per cent in the March 1998 benefit system are reduced to 30 per cent, while leaving all basic benefit levels unchanged. This change is therefore expected to ‘flatten’ the tax structure by reducing the high marginal tax rates applying to those with relatively low incomes and increasing the marginal tax rates of medium incomes. Simulations in which all individuals are assumed to remain at their pre‐reform labour supply levels are compared with behavioural simulations in which the majority of individuals are free to adjust the number of hours worked. The results reflect only the supply side of the labour market. The database used is the 1997‐98 Survey of Income and Housing Costs, so that weekly incomes are based on the financial year 1997‐98. The comparison shows that, for sole parents, accounting for behavioural effects of the reform results in a lower estimated expenditure for government, whereas for couples, accounting for behavioural effects results in a higher estimated expenditure.

English in Australia

Given the federal structure in Australia, there is no national curriculum in English. Instead, the various states are responsible for school education, including English education. However, events over the last half century at least have caused the federal government to assume an increasing amount of power in the provision of education. Broadly two themes emerge from a review of English curricula in Australia over the last 40 years or so. One has involved significant changes in the manner in which the content of subject English has been conceived. The other has been the increased power and influence the federal government has come to exercise in the provision of English programs. Nowadays, 'English' is often almost synonymous with 'literacy', and governments, both federal and state, pursue programs designed to lift the levels of literacy in schools. The preoccupation with 'literacy' often at the expense of a richer model of subject English, has left the subject rather impoverished. There is a need to reinvent English, giving it a clearer and more coherent focus if it is to survive.

A recommended earthquake response spectrum model for Australia

Response spectrum provisions in the current Australian Earthquake Loading Standard (AS1170.4) were based on recommendations from the 1991 edition of the Uniform Building Code for the United States. Since the implementation of AS1170.4 in 1993 there have been significant developments internationally and in Australia in the area of response spectrum modelling on both rock and soil sites. In this paper, a new normalised design response spectrum is recommended for rock sites in Australia based on a response spectral velocity of 1.8 times the peak ground velocity, and corner periods of T1=0.35secs and T2=1.5secs (based on a magnitude 7 earthquake event). The recommended rock response spectra for 500 year return period is generally consistent with the AS1170.4 spectrum in the low period range, however, more accurately represents the displacement demand expected in the higher period range. Recommendations for the development of response spectra for soil sites have also been presented in ADRS format for use with the capacity spectrum method, to assess the seismic performance of new and existing structures in Australia. A brief introduction to the method has been presented in the paper.