A framework for predicting the residual load carrying capacity of concrete structures exposed to aggressive environments

Reinforced concrete structures are susceptible to a variety of deterioration mechanisms due to creep and shrinkage, alkali-silica reaction (ASR), carbonation, and corrosion of the reinforcement. The deterioration problems can affect the integrity and load carrying capacity of the structure. Substantial research has been dedicated to these various mechanisms aiming to identify the causes, reactions, accelerants, retardants and consequences. This has improved our understanding of the long-term behaviour of reinforced concrete structures. However, the strengthening of reinforced concrete structures for durability has to date been mainly undertaken after expert assessment of field data followed by the development of a scheme to both terminate continuing degradation, by separating the structure from the environment, and strengthening the structure. The process does not include any significant consideration of the residual load-bearing capacity of the structure and the highly variable nature of estimates of such remaining capacity. Development of performance curves for deteriorating bridge structures has not been attempted due to the difficulty in developing a model when the input parameters have an extremely large variability. This paper presents a framework developed for an asset management system which assesses residual capacity and identifies the most appropriate rehabilitation method for a given reinforced concrete structure exposed to aggressive environments. In developing the framework, several industry consultation sessions have been conducted to identify input data required, research methodology and output knowledge base. Capturing expert opinion in a useable knowledge base requires development of a rule based formulation, which can subsequently be used to model the reliability of the performance curve of a reinforced concrete structure exposed to a given environment.

Benchmarks for recycling practices in commercial office building refurbishment : data collection challenges

In recent years considerable effort has gone into quantifying the reuse and recycling potential of waste generated by residential construction. Unfortunately less information is available for the commercial refurbishment sector. It is hypothesised that significant economic and environmental benefit can be derived from closer monitoring of the commercial construction waste stream. With the aim of assessing these benefits, the authors are involved in ongoing case studies to record both current standard practice and the most effective means of improving the eco-efficiency of materials use in office building refurbishments. This paper focuses on the issues involved in developing methods for obtaining the necessary information on better waste management practices and establishing benchmark indicators. The need to create databases to establish benchmarks of waste minimisation best practice in commercial construction is stressed. Further research will monitor the delivery of case study projects and the levels of reuse and recycling achieved in directly quantifiable ways

Building infrastructure asset management : Australian practices

Generally, major public funding is invested in civil infrastructure assets. The efficiency and comfort level of expected and actual living standards is largely dependant on the management strategies of these assets. Buildings are one of the major & vital assets, which need to be maintained primarily to ensure their functionality by effective & efficient delivery of services and to optimise economic benefits. In Australia, billions of dollars are spent annually managing and maintaining built assets. These assets make up the social and economic infrastructure, which facilitate the essential services to public and business. Buildings are one of the prime & fundamental assets, which need to be managed effectively and efficiently to ensure that related services are delivered economically and sustainably

Estimating indoor air quality using integrated 3D CAD building models

The indoor air quality (IAQ) in buildings is currently assessed by measurement of pollutants during building operation for comparison with air quality standards. Current practice at the design stage tries to minimise potential indoor air quality impacts of new building materials and contents by selecting low-emission materials. However low-emission materials are not always available, and even when used the aggregated pollutant concentrations from such materials are generally overlooked. This paper presents an innovative tool for estimating indoor air pollutant concentrations at the design stage, based on emissions over time from large area building materials, furniture and office equipment. The estimator considers volatile organic compounds, formaldehyde and airborne particles from indoor materials and office equipment and the contribution of outdoor urban air pollutants affected by urban location and ventilation system filtration. The estimated pollutants are for a single, fully mixed and ventilated zone in an office building with acceptable levels derived from Australian and international health-based standards. The model acquires its dimensional data for the indoor spaces from a 3D CAD model via IFC files and the emission data from a building products/contents emissions database. This paper describes the underlying approach to estimating indoor air quality and discusses the benefits of such an approach for designers and the occupants of buildings.

Listening to nature : acoustic monitoring of the environment

The requirement to monitor the rapid pace of environmental change due to global warming and to human development is producing large volumes of data but placing much stress on the capacity of ecologists to store, analyse and visualise that data. To date, much of the data has been provided by low level sensors monitoring soil moisture, dissolved nutrients, light intensity, gas composition and the like. However, a significant part of an ecologist’s work is to obtain information about species diversity, distributions and relationships. This task typically requires the physical presence of an ecologist in the field, listening and watching for species of interest. It is an extremely difficult task to automate because of the higher order difficulties in bandwidth, data management and intelligent analysis if one wishes to emulate the highly trained eyes and ears of an ecologist. This paper is concerned with just one part of the bigger challenge of environmental monitoring – the acquisition and analysis of acoustic recordings of the environment. Our intention is to provide helpful tools to ecologists – tools that apply information technologies and computational technologies to all aspects of the acoustic environment. The on-line system which we are building in conjunction with ecologists offers an integrated approach to recording, data management and analysis. The ecologists we work with have different requirements and therefore we have adopted the toolbox approach, that is, we offer a number of different web services that can be concatenated according to need. In particular, one group of ecologists is concerned with identifying the presence or absence of species and their distributions in time and space. Another group, motivated by legislative requirements for measuring habitat condition, are interested in summary indices of environmental health. In both case, the key issues are scalability and automation.

A model for the uptake of E-business by building small and medium enterprises

The adoption of e-business by Small and Medium Enterprises (SMEs) in construction lags from other service and product businesses within the building sector. This paper develops a model to facilitate the uptake of electronic business, especially in relation to SMEs within the Australian construction sector. Ebusiness is defined here as “the undertaking of business-related transactions, communications and information exchanges utilising electronic medium and environment”, the elicited model highlights significant changes needed including skills development, social, economic and cultural issues. The model highlights barriers for SMEs to migrate towards e-transactions, e-bidding, e-tendering and ecollaboration and provides learning and skills development components. The model is derived from case study fieldwork and is to inform diffusion and awareness models for best practice. Empirical techniques included ‘focus group’ interviews and one to one ‘interviews’. Data was transcribed and analysed using cluster analyses. Preliminary results reveal that current models for e-business adoption are not effective within the construction context as they have emerged from other service and product industries - such as retail or tourism. These generic models have largely ignored the nature of the construction industry, and some modifications appears to be required. This paper proposes an alternative adoption model which is more sensitive to the nature of the industry – particularly for e-business uptake in building SME’s.

Sustainability and the Building Code of Australia

This was a two-stage project to inform the Australian property and construction industry generally, and to provide the Australian Building Codes Board (ABCB) with information to allow it to determine whether or not sustainability requirements are necessary in the Future Building Code of Australia (BCA21). Research objectives included: examine overseas sustainability requirements for buildings and outline the reason why it is controlled and regulated in the particular country, state, principality etc. examine studies focusing on sustainability developments in buildings in Australia and overseas identify potential issues and implications associated with sustainable building requirements provide advice on whether provisions are necessary in the BCA21 to make buildings sustainable if the study determines there is a need for sustainability requirements in the BCA21, the study was to demonstrate the need to control and regulate along with the method to control and regulate. This research was broken down into two stages. Stage 1 was a literature review of international requirements as well as current thinking and practice for sustainable building developments. Stage 2 identified issues and implications of sustainability requirements for buildings and advice on whether provisions are necessary in the BCA21. This stage included workshops in all capital cities and involved key stakeholders, such as regulators, local government and representatives from key associations. This final report brings together the work of both stages, along with a searchable internet database of references and a series of nine key recommendations.

eValuBuild

The overall goal of the project was to provide a tool for improved investment decision making for functional performance of investment property. The evaluation examines both ex post and ex ante building performance within operational and investment contexts and considers the resultant financial, environmental and social impacts.

Comparative study of guidelines and practices for building infrastructure asset management

This paper presents a comparative study of primarily Australian (and limited international) practices and guidelines on Buildings Asset Management (BAM). The objective of this study was to identify potential gaps in current practices and potential areas of research for further improvement. The paper starts with an overview of BAM. Later sections cover current BAM practices and guidelines across different states of Australia; give a limited overview of international practices and concludes with the authors’ observations.

Towards a building sustainability assessment framework

This paper provides an overview of a new framework for a design stage Building Environmental Assessment (BEA) tool and a discussion of strategic responses to existing tool issues and relative stakeholder requirements that lead to the development of this tool founded on new information and communication technology (ICT) related to developments in 3D CAD technology. After introducing the context of the BEA and some of their team’s new work the authors • Critique current BEA tool theory; • Review previous assessments of stakeholder needs; • Introduce a new framework applied to analyse such tools • Highlight and key results considering illustrative ICT capabilities and • Discuss their potential significance upon BEA tool stakeholders.

Identification of key environmental issues for building materials

Manufacture, construction and use of buildings and building materials make a significant environmental impact internally (inside the building), locally (neighbourhood) and globally. Life cycle assessment (LCA) methodology is being applied for evaluating the environmental impact of building/or building materials. One of the major applications of LCA is to identify key issues of a product system from cradle to grave. Key issues identified in an LCA lead one to the right direction in assessing the environmental aspects of a product system and help to identify the areas for improvement of the environmental performance of a product as well. The purpose of this paper is to suggest two methods for identifying key issues using an integrated tool (LCADesign), which has been developed to provide a method of determining the best alternative for reducing environmental impacts from a building or building materials, and compare both methods in the case study. This paper assists the designers or marketers related to building or building materials in their decision making by giving information on activities or alternatives which are identified as key issues for environmental impacts.

Selection method for sustainable building

For a sustainable building industry, not only should the environmental and economic indicators be evaluated but also the societal indicators for building. Current indicators can be in conflict with each other, thus decision making is difficult to clearly quantify and assess sustainability. For the sustainable building, the objectives of decreasing both adverse environmental impact and cost are in conflict. In addition, even though both objectives may be satisfied, building management systems may present other problems such as convenience of occupants, flexibility of building, or technical maintenance, which are difficult to quantify as exact assessment data. These conflicting problems confronting building managers or planners render building management more difficult. This paper presents a methodology to evaluate a sustainable building considering socio-economic and environmental characteristics of buildings, and is intended to assist the decision making for building planners or practitioners. The suggested methodology employs three main concepts: linguistic variables, fuzzy numbers, and an analytic hierarchy process. The linguistic variables are used to represent the degree of appropriateness of qualitative indicators, which are vague or uncertain. These linguistic variables are then translated into fuzzy numbers to reflect their uncertainties and aggregated into the final fuzzy decision value using a hierarchical structure. Through a case study, the suggested methodology is applied to the evaluation of a building. The result demonstrates that the suggested approach can be a useful tool for evaluating a building for sustainability.

Variations in MIMO-OFDM channel capacity due to random human movement in an indoor environment

Channel measurements and simulations have been carried out to observe the effects of pedestrian movement on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel capacity. An in-house built MIMO-OFDM packet transmission demonstrator equipped with four transmitters and four receivers has been utilized to perform channel measurements at 5.2 GHz. Variations in the channel capacity dynamic range have been analysed for 1 to 10 pedestrians and different antenna arrays (2 × 2, 3 × 3 and 4 × 4). Results show a predicted 5.5 bits/s/Hz and a measured 1.5 bits/s/Hz increment in the capacity dynamic range with the number of pedestrian and the number of antennas in the transmitter and receiver array.

Redefining life cycle for a building sustainability assessment framework

Understanding the differences between the temporal and physical aspects of the building life cycle is an essential ingredient in the development of Building Environmental Assessment (BEA) tools. This paper illustrates a theoretical Life Cycle Assessment (LCA) framework aligning temporal decision-making with that of material flows over building development phases. It was derived during development of a prototype commercial building design tool that was based on a 3-D CAD information and communications technology (ICT) platform and LCA software. The framework aligns stakeholder BEA needs and the decision-making process against characteristics of leading green building tools. The paper explores related integration of BEA tool development applications on such ICT platforms. Key framework modules are depicted and practical examples for BEA are provided for: • Definition of investment and service goals at project initiation; • Design integrated to avoid overlaps/confusion over the project life cycle; • Detailing the supply chain considering building life cycle impacts; • Delivery of quality metrics for occupancy post-construction/handover; • Deconstruction profiling at end of life to facilitate recovery.

Best Practice Guide : Generic Overview

The construction industry is a key national economic component. It tends to be at the forefront of cyclic changes in the Australian economy. It has a significant impact, both directly and indirectly, on the efficiency and productivity of other industries. Moreover it affects everyone to a greater or lesser extent; through its products whether they are manifested in the physical infrastructure that supports the operation of the economy or through the built environment that directly impacts on the quality of life experienced by individuals. In financial terms the industry makes one of the largest contributions to the Australian economy, accounting for 4.7 per cent of GDP 1 which was worth over $30B in 20012. The construction industry is comprised of a myriad of small firms, across several important sectors including, o Residential building, o Commercial building, o Building services, o Engineering, o Infrastructure o Facilities Management o Property Development Each sector is typified by firms that have distinctive characteristics such as the number of employees, size and value of contracts, number of jobs, and so forth. It tends to be the case that firms operating in commercial building are larger than those involved in residential construction. The largest contractors are found in engineering and infrastructure, as well as in the commercial building sub-sectors. However all sectors are characterised by their reliance upon sub-contractors to carry out on-site operations. Professionals from the various design consultant groups operate across all of these sectors. This description masks one of the most significant underlying causes of inefficiency in the construction industry, namely its fragmentation. The Construction Industry chapter of the 2004 Australian Year Book3, published by the Australian Bureau of Statistics unmasks the industry’s fragmented structure, typified by the large number of operating businesses within it, the vast majority of which are small companies employing less than 5 people. It identifies over 190,000 firms, of which over 90 percent employ less than 5 people. At the other end of the spectrum, firms employing 20 or more people account for fractionally more than one percent of businesses in the industry.