Infrastructure Engineering - Research Publications
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ItemNo Preview AvailableParametric study of the effect of thermal properties and ambient temperature on tensile stress and strength development in mass concrete(The International Federation for Structural Concrete (FIB), 2019-01-01)Thermal stress typically takes place at early ages when concrete is undergoing exothermic hydration reaction and is restricted from expansion and contraction by surrounding structural elements. In mass concrete structures, the relatively large temperature differences between the core and the surface produce differential dilation which leads to tensile stresses. Potential tensile cracks develop when the stress experienced by the concrete exceeds the concurrent strength of the maturing concrete. This effect in turn can lead to performance reduction, or in some instances, instability of structure and must be dealt with care. While published literature reports extensively on hydration based mechanical properties of concrete, only a few has considered investigating the in-situ performance of the material accounting for thermal stresses. In what concerns crack formation, consideration of the thermo-mechanical boundary conditions are important nuts that have not been investigated explicitly. This research aims to provide insight into the impacts of thermal related parameters on early age concrete crack formation through computational modelling.
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ItemMaintenance of building structural systems(Nethwin Printers, 2016)The aim of this paper is to review the current literature on maintenance of building structural systems. It emphasises the importance of maintenance as an item for consideration from the beginning of the conceptual design stage. Building sustainability concept is generally understood to have better energy efficiency focus and maintenance of structural components ensures they serve their designed service life and beyond. The conventional design approach considers structural maintenance during the “product use” phase. This paper argues that if the accessibility of the building and maintenance (inspection, repair and retrofitting) are considered from the early conceptual design stage, it would save resources and maintenance cost. Case studies of buildings subject to earthquake loading and corrosion and their maintenance are presented.
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ItemBehaviour of Pre-Stressed High Strength Concrete Sleepers Subjected To Dynamic Loads(University of Queensland, 2015)
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ItemStrain Rates in Pre-stressed Concrete Sleepers and Effects on Cracking Loads(RMIT, 2014)Pre-stressed concrete sleepers (PCSs) play an essential role in railway track response, performance and safety. Depending on track condition and train speed, PCSs are subjected to high magnitude dynamic loads. These loads can generate cracks, which influence the stiffness, load bearing capability and durability of sleepers. The cracking of PCSs has been reported to be a major problem on a worldwide scale and imposes a costly replacement. This paper presents an investigation on the effects of calculating strain rates on the strength of PCS. By using available measurements, the strain rates are calculated at the rail seat and midspan, locations with a high concentration of stress. The cracking loads are calculated based on the dynamic increase factor (DIF) of concrete and comparison is made with commonly occurring dynamic loads. Results show that the maximum strain rates at both rail seat and midspan are about 0.08 and 0.016 1/s, respectively. The increase of cracking wheel load due to the strain rate effects is about 5 to 26 percent Further, the results are shown to be able to demonstrate the level of concrete damage in the form of cracks due to dynamic loads with very short return periods.