Infrastructure Engineering - Research Publications

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    Airborne and impact sound performance of modern lightweight timber buildings in the Australian construction industry
    Jayalath, A ; Navaratnam, S ; Gunawardena, T ; Mendis, P ; Aye, L (Elsevier BV, 2021-12)
    Timber usage in the Australian construction industry has significantly increased due to its strength, aesthetic properties and extended allowances recently introduced in building codes. However, issues with acoustic performance of lightweight timber buildings were reported due to their inherit product variability and varying construction methods. This article reviews the recent literature on the transmissions of impact and airborne sounds, flanking transmission of timber buildings, and the state of computer prediction tools with reference to the Australian practice. An in-depth analysis of issues and an objective discussion related to acoustic performance of timber buildings are presented. Timber is a lightweight material and shows low airborne sound resistance in low frequency range. Attenuation of sound transmission with addition of mass, layer isolation, different products like cross-laminated timber and prefabrication are discussed. Challenges in measuring sound transmissions and reproducibility of results in low frequency ranges are discussed. Well-defined measurement protocols and refined computer simulation methods are required. The serviceability design criteria for modern lightweight timber applications in Australia need to be re-evaluated in the area of impact generated sound. Developing computer tools to predict airborne and impact sound transmission in lightweight timber buildings is quite challenging as several components such as timber members and complex connections with varying stiffnesses are non-homogeneous by nature. Further, there is a lack of experimentally validated and computationally efficient tools to predict the sound transmission in timber buildings. Computer prediction tools need to be developed with a focus on mid-frequency transmission over flanks and low-frequency transmission of timber and prefabricated buildings.
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    Optimising the computational domain size in CFD simulations of tall buildings
    Abu-Zidan, Y ; Mendis, P ; Gunawardena, T (Elsevier, 2021-04-01)
    Recently, there has been a growing interest in utilizing computational fluid dynamics (CFD) for wind resistant design of tall buildings. A key factor that influences the accuracy and computational expense of CFD simulations is the size of the computational domain. In this paper, the effect of the computational domain on CFD predictions of wind loads on tall buildings is investigated with a series of sensitivity studies. Four distinct sources of domain error are identified which include wind-blocking effects caused by short upstream length, flow recirculation due to insufficient downstream length, global venturi effects due to large blockage ratios, and local venturi effects caused by insufficient clearance between the building and top and lateral domain boundaries. Domains based on computational wind engineering guidelines are found to be overly conservative when applied to tall buildings, resulting in uneconomic grids with a large cell count. A framework for optimizing the computational domain is proposed which is based on monitoring sensitivity of key output metrics to variations in domain dimensions. The findings of this paper help inform modellers of potential issues when optimizing the computational domain size for tall building simulations.
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    Impact of atmospheric boundary layer inhomogeneity in CFD simulations of tall buildings
    Abu-Zidan, Y ; Mendis, P ; Gunawardena, T (Elsevier BV, 2020-07)
    Recently, there has been a growing interest in utilizing computational fluid dynamics (CFD) for wind analysis of tall buildings. A key factor that influences the accuracy of CFD simulations in urban environments is the homogeneity of the atmospheric boundary layer (ABL). This paper aims to investigate solution inaccuracies in CFD simulations of tall buildings that are due to ABL inhomogeneity. The investigation involves two steps. In the first step, homogenous and inhomogeneous ABL conditions are generated in an empty computational domain by employing two different modelling approaches. In the second step, the homogenous and inhomogeneous conditions are each applied to an isolated tall building, and simulation results are compared to investigate impact of ABL inhomogeneity on wind load predictions. The study finds that ABL inhomogeneity can be a significant source of error and may compromise reliability of wind load predictions. The largest magnitude of inhomogeneity error occurred for pressure predictions on the windward building surface. Shortening the upstream domain length reduced inhomogeneity errors but increased errors due to wind-blocking effects. The study proposes a practical approach for detecting ABL inhomogeneity that is based on monitoring sensitivity of key output metrics to variations in upstream domain length.
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    Performance of multi-storey prefabricated modular buildings with infill concrete walls subjected to earthquake loads
    Gunawardena, D ; Ngo, T ; Mendis, P ; Kumar, S (Concrete Institute of Australia (CIA), 2017-09-14)
    Prefabricated modules are increasingly becoming popular in the construction industry as they result in achieving cost efficient buildings in a very short time. This increasing demand for modular construction has expanded to multi-storey applications where the effect of lateral loads, such as earthquake loads, becomes critical. However, there is a shortage of detailed engineering research into the performance of modular structural systems subjected to earthquake loads. This paper evaluates a modified corner supported modular structural system that uses infill concrete walls to enhance its lateral stiffness. The performance of the overall structural system against earthquake loads and the contribution of modules containing infill concrete walls to the overall lateral load resisting system is discussed in this paper.
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    Effective use of offsite manufacturing for public infrastructure projects in Australia
    Gunawardena, D ; Mendis, P ; Ngo, D ; Rismanchi, B ; Aye, L (ICE Publishing, 2019)
    Prefabrication and offsite manufacturing have featured in various forms in an in-situ based construction industry for many decades. Scarcity of both human and material resources is challenging the future of traditional construction practices. Due to its many benefits such as speed of project delivery, minimum work on site, minimised construction waste and higher quality assurance, offsite manufacturing is gradually evolving into an essential technology in the construction industry. As a result of re-cent government initiatives, Australia is seeing a considerable increase in the use of offsite manufacturing and prefabricated modular technologies in delivering public infrastructure projects such as schools, healthcare facilities, and public transport facilities. Such projects are ably supported by academic research collaborating with the industry to ensure that the outcomes keep improving to achieve the highest quality and functionality. This paper discusses how multidisciplinary research addresses issues such as structural performance, construction technology, design for manufacturing and assembly and indoor environ-mental quality for the delivery of such public infrastructure projects. These projects have set an example in how offsite manufacturing supported by academic research can be beneficial for effectively delivering the greater good to the society.
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    A holistic model for designing and optimising sustainable prefabricated modular buildings
    Gunawardena, DS ; Ngo, TD ; Mendis, PA ; Aye, L ; Crawford, RH ; Alfano, JA (University of Moratuwa, 2012)
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    Wind induced fatigue analysis of Lotus Tower Mast
    Mendis, P ; Fernando, S ; Holmes, JD ; Gunawardena, T ; Abu-Zidan, YOUSEF ; Dias, P (Australian Wind Engineering Society, 2018)
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    An optimum construction strategy for multi-story residential prefabricated modular buildings
    Thalpe Guruge, ; Samarasinghe, ; Gunawardena, ; Nguyen, T ; Mendis, P ; Ngo, T ; Aye, L (ZEMCH Network, 2018-01-29)
    Prefabrication is recognised as the way forward in building construction by the industry as it delivers quality yet affordable mass customisable houses faster than traditional on-site construction. The prefabrication of multi-story buildings transforms traditional construction into off-site manufacturing of repetitive components. Currently there are three main structural systems being adopted for modular multi-story buildings; 1) Building with a rigid in-situ central core to which the modules are connected, 2) A podium structure which acts as a base where modules are placed on top of it, 3) Fully modular structure with strategically placed load bearing modules. Current investigations on these systems focus on improving their benefits such as construction time, cost, safety and quality based on one variable at a time. However, there is a lack of studies with a holistic approach to identify the optimum structural system. This paper aims to define an Optimum Modular System Index (OMI) which will be based upon three main indices; Assembly cost penalty Index (ACPI), Onsite handling cost penalty Index (HCPI) and Concrete cost penalty Index (CCPI). Determination of OMI is expected to provide a framework to identify the optimum construction system for multi-story residential prefabricated modular buildings.