Infrastructure Engineering - Research Publications

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    Design and Development of Weatherproof Seals for Prefabricated Construction: A Methodological Approach
    Orlowski, K ; Shanaka, K ; Mendis, P (MDPI, 2018-09-01)
    Satisfactory weatherproofing of buildings is vital to maximise their design life and performance which requires the careful design of external sealing technologies. Systems commonly available have served well in conventional construction however with many prefabricated systems emerging in the building industry new and novel means of weatherproofing between panels and modules need to be developed purpose specific to this application. This paper presents a holistic and fundamental methodological approach to Design and Development of waterproof seals and has been applied specific for prefabricated panelised and modular systems. Two purpose specific weatherproof seals are finally presented. Flow charts of the overview of the suggested methodological approach and the processes within which include DfMA that have been incorporated into understanding and developing seals for this practical application. These strategies have enabled a resourceful and holistic set of processes that can be adapted and used for similar forms of product research in new and developing areas of construction such as prefabrication. The design and development process is thoroughly investigated and has resulted in an exploration of the technical challenges and potential solutions which take into consideration factors from installation limitations to building tolerances.
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    Prefabrication of substructures for single-detached dwellings on reactive soils: a review of existing systems and design challenges
    Teodosio, B ; Baduge, KSK ; Mendis, P ; Heath, DJ (Taylor & Francis, 2019-08-27)
    The possible thriving Australian construction industry for residential structures has been hindered by skilled labour shortage and eventually triggered housing shortage and affordability crisis. Prefabrication is a promising method to alleviate issues related to housing shortage and affordability by reducing material wastage, construction delays, weather impacts, unexpected costs, skilled labour dependence and construction risks. The full potential of prefabricated construction is yet to be realised in part due to most of developments being focused on its superstructure. Prefabricated substructures should conform with the Ultimate Limit State (i.e. strength capacity) and the Serviceability Limit State (i.e. allowable deformation and damage) stated in the Australian Standards. Due to the initiatives to alleviate issues of housing crisis, skilled labour shortage and unpredictable house damage, it is necessary to review the existing available substructures suitable for single-detached dwellings on reactive soils and to evaluate the necessary considerations and challenges in developing prefabricated substructures. This review will help understand the present state of the design and construction industry and the efforts of inventors and designers to reduce damages due to the shrinking and swelling ground movements. This review also guides product developers to design systems having robust performance without compromising practicality.
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    Performance of lightweight hemp concrete with alkali-activated cenosphere binders exposed to elevated temperature
    Kristombu Baduge, S ; Mendis, P ; San Nicolas, R ; Nguyen, K ; Hajimohammadi, A (Elsevier BV, 2019-11-10)
    This study investigates the performance of three different types of cenosphere as a lightweight supplementary cementitious material for alkali-activated binder for lightweight carbon-negative hemp-concrete for non-load bearing applications. Mechanical performance of hemp concrete exposed to three temperatures, room temperature (RT), 300 °C and 600 °C are studied using mechanical testing, thermogravimetric analysis (TGA) and Fourier-transform Infrared Spectroscopy (FTIR). Hemp concrete with cenosphere binder remained its integrity and showed a lower load carrying capacity even after exposure to elevated temperatures. Compressive strength capacity and elastic modulus of the samples reduced with the increase of temperature and shows the composite material is more suitable for non-load bearing application considering its mechanical behavior and fire requirements. The density, age, and type of cenosphere showed effects on mechanical properties at room temperature and elevated temperatures. The study shows that alkali activated cenosphere binders can potentially be a sustainable alternative to the lime binder.
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    Structural behaviour of prefabricated stressed-skin engineered timber composite flooring systems
    Orlowski, K ; Baduge, SK ; Mendis, P ; Oktavianus, Y (Elsevier, 2019-12-01)
    The primary focus of this study is understanding the behaviour and structural performance of prefabricated composite timber floor cassette systems with Oriented strand board (OSB) stressed-skins. These do not have a dedicated top flange, instead their plywood webs are integrally bonded to the OSB flooring skin through a chemical connection. Subsequently, local buckling of the stressed-skin was found to occur as the first failure mode. Specimens with 150 mm and 300 mm nail spacings were investigated for its effects on performance due to the criticality of the integrated web to floor skin connection in these systems. A total of 20 stressed-skin specimens were tested in three-point bending with recordings of the applied force, displacement, slip and failure modes. It was found that local buckling of the skin is prone to occur prior to reaching the designed SLS limit. A detailed Finite Element Analysis (FEA) which takes into consideration the full behaviour of the materials and the glue and nail connections along with failure modes has been validated and used to provide insight to potential design solutions. Key parameters investigated include the adhesive properties, the ratio of clear effective outstand width of the flange to the thickness of the stressed-skin (beff,o/t), ratio of the clear depth of the web to the thickness of the web (dp/tw), ratio of the clear span to the total depth of the composite beam (Lc/D) and finally the spacing of the nails. This has resulted in a broad level understanding of the effects of these design parameters to the behaviour of stressed-skin engineered timber flooring cassettes.
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    Novel energy-based rational for nominal ductility design of very-high strength concrete columns (>100 MPa)
    Kristombu Baduge, S ; Mendis, P (Elsevier Ltd, 2019-11-01)
    Ductility forewarns the failure and enables a structure to undergo large deformation while sustaining load carrying capacity and dissipate energy in an earthquake event. Considering recent advances in energy-based seismic design approach, presenting a novel energy-based ductility design approach for nominal ductility design of VHSC (> 100 MPa) columns while considering the higher plastic energy within the VHSC columns is the focus of the study. In this paper, an accurate program to predict analytical full-range moment-curvature relation using appropriate stress-strain behavior of constitutive materials is used to predict the energy-based and curvature ductility of rectangular VHSC columns including possible failure mechanisms. Considering deficiencies in existing ductility indices for VHSC, the study proposes energy-based ductility indices and discusses the suitability for nominal ductility design. The threshold for nominal ductility design of a VHSC column is proposed as the flexural rotation-based energy ductility level (Eθ) of a similar 50 MPa concrete column which is a similar approach to the nominal ductility design method in the Australian Concrete Structures Standard, AS 3600 [1]. It showed that the new approach reduces the required amount of confinement steel because the new index can represent the increase of energy ductility of VHSC columns accurately, at higher axial load levels and higher strengths. Using this approach practical amount of lateral steel and spacing can be suggested for rectangular VHSC columns with compressive strengths up to 150 MPa which enables the use and economical designs of VHSC for nominal ductile structures.
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    Ductility Design of Reinforced Very-High Strength Concrete Columns (100–150 MPa) Using Curvature and Energy-Based Ductility Indices
    Kristombu Baduge, S ; Mendis, P ; Ngo, TD ; Sofi, M (Springer Science and Business Media LLC, 2019-12-01)
    The paper aims to develop theoretical expressions for the ductility design of very-high strength concrete (VHSC) (> 100 MPa) columns using curvature and a new flexural energy-based ductility approach. Eventually, the study aims to evaluates the feasibility of VHSC columns for different ductility classes, considering the limitation of providing a higher volume of transverse reinforcement due to possible steel congestion in the construction phase. An analytical program based on the experimental stress–strain relationship of confined VHSC, which is validated using experimental programs on VHSC columns, is used to evaluate the ductility of VHSC columns for different parameters such as axial load ratio, confinement pressure, longitudinal steel ratio, yield strength of transverse steel, cover area and compressive strength of concrete. The theoretical curvature ductility and flexural rotation-based energy ductility of 3200 rectangular columns were evaluated using the analytical program. Using curvature ductility and the new flexural rotation-based energy ductility for different parameters, a regression analysis is carried out to develop expressions for the ductility design of VHSC columns up to 150 MPa. Using the new definition of energy-based ductility, a new expression is developed for limited ductility design of VHSC; and it is concluded that the new approach reduces the required amount of steel confinement due to an increase in the energy ductility of VHSC at higher axial load ratios and higher strengths. The studies show that reinforced VHSC can be used for structures with nominal ductility demands.
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    Fire resistance of a prefabricated bushfire bunker using aerated concrete panels
    Nguyen, T ; Ngo, DT ; Tran, P ; Mendis, P ; Aye, L ; Kristombu Baduge, KS (Elsevier, 2018-06-20)
    Prefabricated lightweight aerated concrete (PLAC) panels provide low thermal conductivity, potentially high stiffness-to-weight ratios, cost-effective material and structural systems and rapid modular construction. These panels can be utilised as floor slabs or external walls for various applications in building construction. The fire performance of the PLAC panel is examined in this work for a particular case, namely a prefabricated emergency bushfire shelter, which is one of the key applications of PLAC panels. Since, bushfires have unique heating curves, standardised tests are not useful and the system needs to be tested in a manner such that the heat flux of an actual bush fire can be reproduced. In this study, the fire performance enhancement of dual-skin bushfire bunkers, which are comprised of lightweight concrete and base metal thickness (BMT) steel, are examined experimentally and validated numerically. The Speedpanel PLAC modular panel explored in this work is a lightweight wall system primarily used for acoustic and thermal insulation purposes. Burning experimental studies of a single panel and dual-skin bunkers are carried out on a full scale. The experimental results are compared with fire safety codes for building materials to identify the key areas for improvements. A fire dynamic numerical model has been developed in this work using the Fire Dynamics Simulator (FDS) to simulate the burning process of PLAC structures. Numerical results of heat production are presented in comparison with experimental observations for validating the computational model. The proposed numerical model is used to predict the fire performance of a dual-skin bushfire bunker, demonstrating the need to have at least two PLAC layers to ensure fire safety compliance.