Sujeeva Setunge

FRAMEWORK FOR INVESTMENT DECISION-MAKING UNDER RISK AND UNCERTAINTY FOR INFRASTRUCTURE ASSET MANAGEMENT

The aim of this paper is to explore the application of risk assessment so that it can be a tool for decisionmakers to confront risk and uncertainty with greater confidence. It can be systematically incorporated into an integrated decisionmaking framework such as a multi-criteria decisionmaking framework. The paper first begins with a presentation of terminology of risk and uncertainty and how current practices incorporate risk and uncertainty in decisionmaking processes. The identification of economic, social, environmental, and other related risk issues for transport infrastructure is then provided, and a formulation of risk assessment is also detailed.

Deterioration Prediction of Timber Bridge Elements Using the Markov Chain

AbstractTimber bridges require high accumulated maintenance costs, which can be many times greater than their initial cost. Infrastructure managers need deterioration models to assist with making appropriate decisions concerning repair strategies and program maintenance schedules by accurately predicting the future condition of timber bridge elements. Markov chain–based models have been used extensively in modeling the deterioration of infrastructure facilities. These models can predict the condition of bridge elements as a probabilistic estimate. This paper presents the prediction of future condition of timber bridge elements using a stochastic Markov chain model. Condition data obtained from the Roads Corporation of Victoria, Australia, were used to develop transition probabilities. The percentage prediction method, regression-based optimization method, and nonlinear optimization technique were applied to predict transition matrices and transient probabilities from the condition data. The most suitable ...

Markov model based building deterioration prediction and ISO factor analysis for building management

AbstractWhile the Markov chain was successfully used for predicting the average condition of a network of assets under one influencing factor, incorporating the effect of a number of factors into a Markov chain model requires a separate analysis of each factor. In particular, modeling building deterioration is overly complicated due to the complexity in number and hierarchy of building components. The research study reported in this paper aims to combine the Markov chain with ISO factor method–based framework to offer a more reliable deterioration forecasting approach for buildings. This paper identifies major influencing factors for building deterioration. It investigates the ability to use Markov chain for deterioration modeling of a selected critical building component. The building condition inspection data from a local government agency in the State of Victoria, Australia, is used to calibrate a Markov deterioration model considering a number of influencing factors. To help demonstrate the concept, t...

An Evaluation of the Learning of Structural Engineering Concepts during the First Two Years of a Project-Based Engineering Degree.

In the modern working environment it is essential for a structural engineer to have an understanding of abstract concepts in structural behaviour and an ability to use them qualitatively. This paper presents the findings of a study on how effectively students acquire such conceptual understanding within a new project/design focused degree course. The new degree programme is described. The first-year students experience a mixture of learning opportunities, including model building/testing, laboratories, workshops/tutorials, and lectures. In the second year there are two design exercises but no formal structural theory course. Specific concepts-based learning material was introduced into the first-year course at mid-semester and the effectiveness of this examined by tests and interviews. The performance of the first-year students is compared to that of the second-year students. The findings show that there is good student engagement and satisfaction with the course and that basic skills are successfully being acquired throughout both years. However, the study highlights areas where concepts are not being adequately developed in the first year and subsequently show little enhancement in the second year.

Environmental Emissions of Construction Equipment Usage in Pile Foundation Construction Process—A Case Study

The level of emissions to the environment imposed by different human activities has been increasing at an alarming rate over the past decades. Measurement and control of air pollutant emissions into the atmosphere can lead towards reducing the emission level considerably. Construction industry is a major contributor to the environmental emissions due to the extensive use of construction equipment, which is responsible for greenhouse gas emissions and harmful substances such as carbon monoxide, nitrogen oxide and particulate matter emissions. Pile foundation is extensively used in high-rise buildings construction and it involves operation of heavy construction equipment. This study developed a process-based model to quantify environmental emissions of equipment usage in a typical pile foundation construction using the US EPA methodology. The emissions of excavation works govern the total emissions at site because of the high usage hours of excavators. In general the emission rates of piling rig and concrete pumping truck were found to be the highest although excavator emission rates are higher for carbon monoxide and particulate matter. It is seen that careful selection of machines and equipment can reduce the emissions up to 10 %. These findings of the study could be effectively used for minimizing the environmental emissions by careful selection of suitable equipment and technology.

Interfacial bond strength of resin-impregnated fibre-reinforced polymer laminates bonded to concrete using vacuum and heat: Experimental study

Two processing techniques commonly used in the repair of concrete structures via bond of fibre-reinforced polymer (FRP) onto the substrate are known as the pultruded plate and wet lay-up systems. The pultruded FRP plate and wet lay-up systems both involve the curing of resins of up to several days under ambient conditions to achieve full load capacity and rely on workmanship to achieve good bond. Hence, new techniques for the application of FRP that adopt a vacuum consolidation process and heat to impregnate FRP fibres with resin to improve the curing process, bond strength and speed of application are being developed. In this article, the interfacial bond behaviour of pre-impregnated FRP laminates attached to concrete in the presence of vacuum and heat is studied and compared to more conventional methods of FRP strengthening systems. Further the effects of bondline thickness on the bond performance of pre-preg FRP laminates are also studied whereby three different bondline thicknesses are examined. The interfacial bond thickness was changed by application of resin films between FRP plates and concrete surface.

Application of Heat/resin Injection in the Presence of Vacuum for FRP Attachments on the Concrete Substrate

Advanced processing techniques for the application of Fibre Reinforced Polymer (FRP) materials to repair concrete structures include the adoption of a vacuum consolidation process coupled with heat and/or resin injection to improve the curing process, bond strength and speed of application. The vacuum can contribute to the penetration of the resin into the surface around the exposed aggregates in order to achieve higher bond in strengthened elements. Since, debonding of FRP materials from the substrate is a brittle failure, it is essential to study this phenomenon and propose significant ways to improve the behaviour of the bondline. In this article, the interfacial bond behaviour of FRP laminates attached to concrete in the presence of vacuum and heat/resin injection is studied. The results of single lap shear tests have been utilized to investigate the capability of this system in strengthening of concrete elements. In this regard, several FRP-bonded concrete prisms will be examined in a single lap shear test set-up. Further, the effects of bondline thickness on the bond performance of adhesively bonded joints are studied.

Council Building Management Practices, Case Studies and Road Ahead

Community building assets in Australia represent a vast investment built up over many generations, and are valued at approximately 15 billion dollars. Further, the second largest class of infrastructure assets owned by councils is the community buildings. It is vital to develop strategic directions for efficient management of these buildings to guarantee the best value and the maximum benefit to the community by delivering the best possible service to the community. Efficient building management should address the aspects of assessing long term performance and developing long term management strategies. This paper investigates the significant aspects of efficient building management through a holistic look at the whole of life infrastructure management process. The contribution of this paper is threefold. First, the paper presents a typical building management process together with the identification of specific elements and/or various stages of the process. This can be easily converted to be applicable to any other infrastructure system. Second, the initial study and data collection conducted at six Victorian city councils covering the council building management practices are presented. These six current practices are analysed and presented as case studies. Third, the paper identifies knowledge/practice gaps between the theoretical foundation of building management process and current practices in the industry. The paper highlights the lessons learnt through the analysis of case studies. Further, it proposes the road ahead of council building management strategy through a holistic analysis of the whole of life infrastructure management process.

Vulnerability of floodways under extreme flood events

Floodways are commonly used in rural road networks due to the economic and environmental benefits offered as a low-cost and practical road crossing in flood-prone areas. They are designed with provision for submergence so that water flows over with minimum impediment to flow, at a probability given design flood. The floodway design process is traditionally governed by hydraulic aspects rather than structural aspects. Hydrological condition, availability of material, and familiarity of construction techniques are significant when selecting the floodway type. Nevertheless, extreme conditions can cause significant damage to floodways, as was evident from the 2011 and 2013 Queensland flood events, during which 58% of floodways in the Lockyer Valley Regional Council (LVRC) area in Queensland, Australia, which is the case study area of this paper, were damaged, causing huge economic lost at council and national level. This created a new track in research and development activities to assess vulnerability and to find methods for improving the resilience of floodways during extreme flood events. In line with this, the present study evaluates local design guidelines and damaged floodways to assess failure modes and severity of damage using a damage index (DI) method.

Use of Markov Chain for Deterioration Modeling and Risk Management of Infrastructure Assets

Current annual expenditure for management and renewal of Infrastructure assets around the world is 500 billion US dollars. With an aging stock of infrastructure, innovative methods for management of risk of failure and optimizing of maintenance expenditure becomes extremely important. Whilst different infrastructure assets may have different attributes, governing issues are similar in nature. Prediction of deterioration of some infrastructure is complex since they can constitute of a number of discrete elements with a vast range of influencing factors. A major issue currently faced by local government agencies in Australia is the inability to predict maintenance and replacement expenditure with a reasonable accuracy, which creates situations where emergency repairs would use the funds kept for routine maintenance, which then creates a vicious circle of deterioration.