Strength of End-Notched Wood Beams: A Critical Fillet Hoop Stress Approach

An equation for predicting the strength of wood beams with end notches on the tension side (Tension-side End Notches or TEN) was derived using a critical fillet hoop stress (CFHS) theory. The equation combines the results of finite element and statistical analyses of 690 different TEN beam configurations and experimental tests of 362 full-size beams. It accounts for the effects of loading type, end support and beam and notch geometry variables such as beam height, fractional notch depth, radius, and notch location. The effect of span-to-depth ratio is implicit to the model. Notched beam strength is represented by a material parameter, k, which can be obtained from notched beam tests. The equation is applicable to both filleted and sharp-cornered notches. An effective radius, Re, which models the effect of a sharp-cornered notch, was determined and confirmed for two wood materials. A method of determining Rc for other materials was established. The results of this study can be used to set new design criteria for the strength of notched wood beams

Response Analysis of Wood Structures Under Natural Hazard Dynamic Loads

The basic requirements needed for response analysis of wood structures against natural hazards are reviewed. A method for stochastic dynamic analysis of wood structures, which allows investigations into their performance and safety under natural hazards such as earthquakes and severe winds, is presented. To illustrate the method, earthquake ground motions are modeled as a stochastic process with Gaussian white noise properties. A single-degree-of-freedom wood structural system is modeled by a hysteretic constitutive law that produces a smoothly varying hysteresis. It models previously observed behavior of wood joints and structural systems, namely, (1) nonlinear, inelastic behavior, (2) stiffness degradation, (3) strength degradation, and (4) pinching. The constitutive law takes into account the experimentally observed dependence of wood joints' response to the input and response at an earlier time (known as memory). Hysteresis shapes produced by the proposed model compare favorably with common wood joints. The hysteresis model can produce a wide variety of hysteresis shapes, degradations, and pinching behavior to model a whole gamut of possible combinations of materials and joint configurations in wood construction. The nonstationary response statistics of a single-degree-of-freedom wood building subjected to white noise excitations are obtained by Monte Carlo simulation and stochastic equivalent linearization. The latter is shown to give a reasonably accurate prediction of the system's response statistics, which may be used in calculating design response values. The method of analysis is general and may be used to study the response of various kinds of structural systems, including multi-degree-of-freedom systems, as long as appropriate structural models are available and appropriate hysteresis model parameters for these systems are known

Existing benchmark systems for assessing global warming potential of buildings – Analysis of IEA EBC Annex 72 cases

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO2e/m2/y, whereas reference values are found between 20-80 kg CO2e/m2/y. Possible embodied target- and reference values are found between 1-12 kg CO2e/m2/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems.publishedVersio

Carbon Footprint Reduction through Residential Building Stock Retrofit: A Metro Melbourne Suburb Case Study

Since existing residential buildings are a significant global contributor to energy consumption and greenhouse gas (GHG) emissions, any serious effort to reduce the actual energy and carbon emissions of the building sector should explicitly address the carbon mitigation challenges and opportunities in the building stock. This research investigates environmentally and economically sustainable retrofit methods to reduce the carbon footprint of existing residential buildings in the City of Greater Dandenong as a case study in Metropolitan Melbourne, Australia. By categorizing energy use into various building age brackets and dwelling types that align with changes in energy regulations, we identified various retrofit prototypes to achieve a targeted 6.5-star and 8-star energy efficiency rating (out of a maximum 10-star rating system). The corresponding operational energy savings through different retrofit options are examined while also considering the quantity of materials required for each option, along with their embodied energy and GHG emissions, thus allowing a more comprehensive lifecycle carbon analysis and exploration of their financial and environmental payback times. Results show that when buildings are upgraded with a combination of insulation and double-glazed windows, the environmental benefits rise faster than the financial benefits over a dwelling’s lifecycle. The size or percentage of a particular dwelling type within the building stock and the remaining lifecycle period are found to be the most important factors influencing the payback periods. Retrofitting the older single detached dwellings shows the greatest potential for lifecycle energy and carbon savings in the case suburb. These findings provide households, industry and governments some guidance on how to contribute most effectively to reduce the carbon footprint of the residential building sector

Urban Sustainability Transition - A 'Tipping Point' Approach

The State of Australian Cities (SOAC) national conferences have been held biennially since 2003 to support interdisciplinary policy-related urban research. This paper was presented at SOAC 3 held in Adelaide from 28 to 30 November 2007. SOAC 3 was jointly hosted by the University of South Australia, the University of Adelaide and Flinders University. Themes and Key Persons SOAC 3 focused on the contemporary form and structure of Australian cities. The conference proceedings were grouped into six key sub-themes, each the focus of one of more conference sessions: City Economy - economic change and labour market outcomes of globalisation, land use pressures, changing employment locations. Social City – including population, migration, immigration, polarisation, equity and disadvantage, housing issues, recreation. City Environment - sustainable development, management and performance, natural resource management, limits to growth, impacts of air, water, climate, energy consumption, natural resource uses, conservation, green space. City Structures – the emerging morphology of the city – inner suburbs, middle suburbs, the CBD, outer suburbs and the urban-rural fringe, the city region. City Governance – including taxation, provision of urban services, public policy formation, planning, urban government, citizenship and the democratic process. City Infrastructure – transport, mobility, accessibility, communications and IT, and other urban infrastructure provision. Paper Review Process Conference papers published from SOAC 3 were produced through a process of integrated peer review. There were originally 147 abstracts proposed, 143 were invited to submit papers and 107 papers were finally published

Spatiotemporal Response of Ecosystem Service Values to Land Use Change in Xiamen, China

This research aims to identify the key indicators of land-use change that affect ecosystem service in the coastal city of Xiamen. The methods of transfer matrix and land-use dynamic degree are used to analyze land-use change, and the spatial distribution of ecosystem service values (ESV) is mapped from 1989 to 2018 using cluster analysis. During this 30-year period, the built-up land expanded rapidly through occupation of farmland and landfilling of the watershed. The biggest contribution to the reduction of ESV in this stage is the loss of farmland followed by the loss of watershed. By 2018, the spatial distribution of ESV had become very unbalanced and polarized. The high-value areas are mainly distributed in the northern mountainous areas, with the low-value areas concentrated in the flat areas near the coastline, and only a few medium-value areas of ESV remained. Generally, from 1989 to 2018, the ESV in Xiamen decreased by about CNY 200 million in total, with the largest proportion of ESV reduction (CNY 120 million) occurring in the 2000–2010 period. Considering ESV categories, the significant reduction of Regulating Service (53.5–57.8%) was mainly due to the loss of water areas (CNY −70 million) to low ESV areas (built-up land) in urbanization, followed by the loss of farmland (CNY −50 million). This means that Xiamen should strengthen the protection of ecological lands in future urban planning to alleviate and reverse the current ecological imbalance

Responding to change in a growing Melbourne : community acceptance, wellbeing, and resilience

In the context of urban population growth, urban consolidation and intensification is a common policy response and challenge across all capital cities in Australia. The urban residents’ views and perceived impacts of different types of intensification will critically shape the nature of what will be accepted and eventually implemented in local suburbs. However, little is known about general attitudes toward urban growth across metropolitan regions. This paper reports on data from a recent Survey of Community Wellbeing and Responding to Change conducted in six Local Government Areas (LGAs) in inner, middle, outer, and urban fringe areas of Melbourne. It examines levels of community acceptance of urban growth in these LGAs, including some alternative explanations which help explain some of the variation in community acceptance of developments related to urban growth. Most important for predicting community acceptance of urban growth were perceptions of a community’s resilience (adaptation) and the associated processes around planning and navigating urban change; and whether changes to suburbs were perceived as varied, mixed and interesting. These alternative explanations provide a point of focus for stakeholders aiming to implement policies around urban consolidation and intensification while maintaining or enhancing community wellbeing. Potential implications of results to policy and further research are identified