Infrastructure Engineering - Research Publications
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ItemStructural Health Monitoring of Bridges Using Advanced Non-destructive Testing Technique(Springer, Singapore, 2020-01-01)This paper presents an integrated framework for structural health monitoring of bridges by using advanced non-destructive testing (NDT) technique in conjunction with computational modelling. First, the structural characteristics of the Eltham Trestle Bridge under train loading were monitored using the combination of the 3D optical measurement system and IBIS-S. The results demonstrate that, in conjunction with computational modelling, the NDT can capture the structural health conditions of the bridge by analysing the natural frequencies and deformation profiles of the critical members of the bridges. Then, the developed framework also takes into account the impact of extreme events (e.g. truck impacts and earthquakes) by using a reliability-based model. Finally, using the Montague Street Bridge as a case study, it shows that proposed framework has the capability of predicting the residual life of a bridge subject to both progressive deterioration and extreme events throughout its service life.
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ItemNo Preview AvailableHollow concrete columns: Review of structural behavior and new designs using GFRP reinforcement(ELSEVIER SCI LTD, 2020-01-15)Hollow concrete columns (HCCs) reinforced with steel bars have been employed extensively for bridge piers, ground piles, and utility poles because they use fewer materials and offer higher structural efficiency compared to solid concrete columns with the same concrete area. Many experimental studies have been conducted to investigate the behavior of HCCs under different loading conditions and found that the structural performance of HCCs is critically affected by many design parameters. If not designed properly, HCCs exhibit brittle failure behavior, due to longitudinal bars buckling or the concrete wall failing in shear. In addition, the corrosion of steel bars has become an issue in reinforced-concrete structures. Therefore, this paper critically reviews the different design parameters that affect the performance of HCCs and identifies new opportunities for the safe design and effective use of this construction system. Moreover, the use of GFRP bars as reinforcement in hollow concrete columns is explored with the aim of developing a non-corroding and structurally reliable construction system.
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ItemNo Preview AvailableA New Design-Oriented Model of Glass Fiber-Reinforced Polymer-Reinforced Hollow Concrete Columns(American Concrete Institute, 2020-03-01)Hollow concrete columns (HCCs) reinforced with glass fiber-reinforced polymer (GFRP) bars and spirals are considered an effective design solution for bridge piers, electric poles, and ground piles because they use less material and maximize the strength-toweight ratio. HCC behavior is affected by critical design parameters such as inner-to-outer diameter ratio, reinforcement and volumetric ratios, and concrete compressive strength. This paper proposes a new design-oriented model based on the plasticity theory of concrete and considering the critical design parameters to accurately describe the compressive load-strain behavior of GFRP-reinforced HCCs under monotonic and concentric loading. The validity of the proposed model was evaluated against experimental test results for 14 full-scale hollow concrete columns reinforced with GFRP bars and spirals. The results demonstrated that the proposed design-oriented model was accurate and yielded a very good agreement with the axial compressive load behavior of GFRP-reinforced hollow concrete columns.
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ItemNo Preview AvailableEffect of Spiral Spacing and Concrete Strength on Behavior of GFRP-Reinforced Hollow Concrete Columns(ASCE-AMER SOC CIVIL ENGINEERS, 2020-02-01)Hollow concrete columns (HCCs) are one of the preferred construction systems for bridge piers, piles, and poles because they require less material and have a high strength-to-weight ratio. While spiral spacing and concrete compressive strength are two critical design parameters that control HCC behavior, the deterioration of steel reinforcement is becoming an issue for HCCs. This study explored the use of glass fiber-reinforced polymer (GFRP) bars as longitudinal and lateral reinforcement for hollow concrete columns and investigated the effect of various spiral spacing and different concrete compressive strengths (f′c). Seven HCCs with inner and outer diameters of 90 and 250 mm, respectively, and reinforced with six longitudinal GFRP bars, were prepared and tested. The spiral spacing was no spirals, 50, 100, and 150 mm; the f′c varied from 21 to 44 MPa. Test results show that reducing the spiral spacing resulted in increased HCC uniaxial compression capacity, ductility, and confined strength due to the high lateral confining efficiency. Increasing f′c, on the other hand, increased the axial-load capacity but reduced the ductility and confinement efficiency due to the brittle behavior of high compressive-strength concrete. The analytical models considering the axial load contribution of the GFRP bars and the confined concrete core accurately predicted the behavior of the HCCs after the spalling of the concrete cover or at the post-loading behavior.
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ItemThe influence of ambient environmental conditions in detecting bridge concrete deck delamination using infrared thermography (IRT)(Wiley, 2020-04-01)Delamination is a serious form of deterioration in concrete bridge decks. Infrared thermography (IRT) is an advance non‐destructive testing method for concrete bridge deck delamination detection by capturing the absolute thermal contrast (ΔT) on the concrete surface caused by the disruption in heat flow due to subsurface defects. However, as the ambient environmental conditions (e.g. wind velocity and solar radiation) of a bridge could significantly affect the measurement outcomes of IRT, the optimal times for infrared data collection are still unclear. In this paper, a series of experimental and numerical studies were carried out to investigate the effects of the rate of heat flux and wind velocity on ΔT on the surface of bridge decks with the aim of identifying the optimal inspection times for different geometry characteristics of delamination (i.e. size and depth). The developed model is firstly validated by the experimental data and then a series of parametric studies were carried out. The result shows that the heat flux rate plays an important role in the development of ΔT on concrete surface, especially for a relatively shallow and small size delamination. However, the influence of heat flux rate gradually diminishes with the increase in size and depth of delamination. In addition, it demonstrates that there is a positive linear correlation between the total heat energy (external irradiation) and square of the delamination depth. The current research represents an important step towards the development of an effective and efficient way for defect detection using IRT.
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ItemImpact of atmospheric boundary layer inhomogeneity in CFD simulations of tall buildings(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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ItemTransversely isotropic elastic-plastic properties in thermal arc sprayed Al–Zn coating: a microporomechanics approach(Springer Science and Business Media LLC, 2020-07-07)The transversely isotropic behaviour of thermal sprayed aluminium and zinc coating has been investigated based on a combination of nanoindentation experimental data and microporomechanics theory. A recently developed strength homogenisation approach comprises of the solid and porous medium is adopted to investigate the morphology properties of thermal sprayed aluminum and zinc coating. The finding of this paper demonstrates that the individual aluminum and zinc phases in the coating have a characteristic packing density close to the theoretical highest spherical packing ratio for face-centred cubic and hexagonal close packed. Also, the plasticity properties of solid particles in both aluminum and zinc are found to have a significant transversely isotropic condition, while the elasticity properties are close to isotropic. These findings led to the conclusion that the anisotropic condition of the coating is dominantly affected by the plasticity properties, in terms of cohesion and friction coefficient.
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ItemUse of fluid structure interaction technique for flash flood impact assessment of structural components(Wiley, 2020-03-01)Prediction of the initial impact force is a major task associated with flood damage assessment of structures subjected to flash flooding especially due to dam break and levee breach. Investigation of failure modes such as overturning and sliding due to soil scouring or erosion is not relevant if the structure first fails by the massive initial dynamic impact. Therefore, a careful assessment of the initial flood impact is critical for the design of structures and during the flood damage assessment process. In most of the past flood damage studies, total flood load acting on the structures was estimated by maximum velocities and water depths obtained from the two‐dimensional hydrodynamic models or the field data. The outcome of these results has shown potential uncertainty in current methods. We present a new approach to calculate the load on structural components impacted by a dam break wave, by modelling the three‐dimensional free surface fluid–structure interaction (FSI) using the incompressible computational fluid dynamics (ICFD) techniques. Two experimental datasets available in the literature are used to validate the results. Finally, we conclude that FSI/IFCD method can be used to accurately determine the initial impact force on structural components subjected to flash floods for flood damage assessment.
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ItemFlexural Performance of Prefabricated Ultra-High-Strength Textile Reinforced Concrete (UHSTRC): An Experimental and Analytical Investigation(MDPI AG, 2020-04-02)Textile Reinforced Concrete (TRC) is a prefabricated novel lightweight high-performance composite material that can be used as a load-bearing or non-load-bearing component of prefabricated buildings. Making TRC with Ultra-High-Strength Concrete (UHSC) (≥100 MPa) can be considered as a potential improvement method to further enhance its properties. This paper investigated the performance of Ultra-High-Strength Textile Reinforced Concrete (UHSTRC) under flexural loading. A detailed experimental program was conducted to investigate the behavior of UHSC on TRC. In the experimental program, a sudden drop in load was observed when the first crack appeared in the UHSTRC. A detailed analytical program was developed to describe and understand such behavior of UHSTRC found in experiments. The analytical program was found to be in good agreement with the experimental results and it was used to carry out an extensive parametric study covering the effects of the number of textile layers, textile material, textile mesh density, and UHSTRC thickness on the performance of UHSTRC. Using a high number of textile layers in thin UHSTRC was found to be more effective than using high-thickness UHSTRC. The high modulus textile layers effectively increase the performance of UHSTRC.
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ItemCohesive-strength homogenisation model of porous and non-porous materials using linear comparison composites and application.(Nature Publishing Group, 2020-02-25)An estimation of the strength of composite materials with different strength behaviours of the matrix and inclusion is of great interest in science and engineering disciplines. Linear comparison composite (LCC) is an approach introduced for estimating the macroscopic strength of matrix-inclusion composites. The LCC approach has however not been expanded to model non-porous composites. Therefore, this paper is to fill this gap by developing a cohesive-strength method for modelling frictional composite materials, which can be porous and non-porous, using the LCC approach. The developed cohesive-strength homogenisation model represents the matrix and inclusion as a two-phase composite containing solids and pores. The model is then implemented in a multiscaling model in which porous cohesive-frictional solids intermix with each other at different scale levels classified as micro, meso and macro. The developed model satisfies an upscaling scheme and is suitable for investigating the effects of the microstructure, the composition, and the interface condition of the materials at micro scales on the macroscopic strength of the composites. To further demonstrate the application of the developed cohesive-strength homogenisation model, the cohesive-strength properties of very high strength concrete are determined using instrumented indentation, nonlinear limit analysis and second-order cone programming to obtain material properties at different scale levels.