Infrastructure Engineering - Research Publications
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ItemAutomation in structural health monitoring of transport infrastructure(Springer Singapore, 2021-01-01)Roads are among the most important assets in the world. Road structure improvements make a crucial contribution to economic development and growth and bring important social benefits. Automation in structural health monitoring allow the accurate prediction of ongoing damage caused by long-term traffic loading. This permits optimal road structure management and ensures the longevity and safety of road structures. This chapter discusses a variety of advanced automation techniques in structural health monitoring of road structures, such as data acquisition, data processing, and life-cycle assessment. It demonstrates that the implementation of automation in road asset management can increase the productivity and extend the service life of road structures, and enhance the durability of crucial road structures and increase transport infrastructure sustainability.
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ItemA Simplified Methodology for Condition Assessment of Bridge Bearings Using Vibration Based Structural Health Monitoring Techniques(WORLD SCIENTIFIC PUBL CO PTE LTD, 2021-09-01)The mechanical properties of bridge bearings gradually deteriorate over time resulting from daily traffic loading and harsh environmental conditions. However, structural health monitoring of in-service bridge bearings is rather challenging. This study presents a bridge bearing condition assessment framework which integrates the vibration data from a non-contact interferometric radar (i.e. IBIS-S) and a simplified analytical model. Using two existing concrete bridges in Australia as a case study, it demonstrates that the developed framework has the capability of detecting the structural condition of the bridge bearings in real-time. In addition, the results from a series of parametric studies show that the effectiveness of the developed framework is largely determined by the stiffness ratio between bridge bearing and girder ([Formula: see text], i.e. the structural condition of the bearings can only be effectively captured when the value of [Formula: see text] ranges from 1/100 and 100.
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ItemLife-cycle modelling of concrete cracking and reinforcement corrosion in concrete bridges: A case study(Elsevier BV, 2021-06-15)The development of effective life cycle management strategies for transport infrastructure assets is of importance for meeting the defined public policies and levels of service. In the last decades, much progress has been made in assessing the life-cycle performance of bridges using reliability-based approaches. However, the goal of developing a comprehensive life-cycle performance assessment framework for bridges has not been fully achieved. This is due to the uncertainties surrounding model parameters as well as the correlation between these parameters (e.g. the complex correlation between the reinforcement corrosion and the concrete cracking). It becomes more challenging due to the limited access to bridge inspection data by bridge research communities resulting from confidentiality issues. Using a typical highway concrete bridge as a case study, the present study systematically investigated the impact of concrete crack induced reinforcement corrosion on the serviceability of concrete bridges by developing an engineering reliability-based approach involving an auto-regressive crack propagation model and a steel corrosion prediction model. The model parameters were calibrated using the eight-year inspection data of an operating bridge. The influence of different external environments in the reinforcement corrosion, ultimately the residual life of the bridges, was also investigated through conducting a series of parametric studies. Based on the collected bridge inspection data, the model results predict that, although the surface crack of a RC bridge is repairable through periodic maintenance, the corrosion of the steel bars in the bridge still continues over time with a corrosion rate which depends on different maintenance intervention cycle periods (Tcycle). For example, reducing Tcycle from 12 years to 4 years could potentially prolong the service life of the bridge by around 15 years. The developed model could assist bridge managers to estimate the optimal Tcycle to prolong the service life of bridges.
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ItemThe investigation of bone fracture healing under intramembranous and endochondral ossification(ELSEVIER, 2021-06)After trauma, fractured bone starts healing directly through bone union or indirectly through callus formation process. Intramembranous and endochondral ossification are two commonly known mechanisms of indirect healing. The present study investigated the bone fracture healing under intramembranous and endochondral ossification by developing theoretical models in conjunction with performing a series of animal experiments. Using experimentally determined mean bone densities in sheep tibia stabilized by the Locking Compression Plate (LCP) fixation system, the research outcomes showed that intramembranous and endochondral ossification can be described by Hill Function with two unique sets of function parameters in mechanical stimuli mediated fracture healing. Two different thresholds exist within the range of mechanical simulation index which could trigger significant intramembranous and endochondral ossification, with a relatively higher bone formation rate of endochondral ossification than that of intramembranous ossification. Furthermore, the increase of flexibility of the LCP system and the use of titanium LCP could potentially promote uniform bone formation across the fracture gap, ultimately better healing outcomes.
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ItemInvestigation of role of cartilage surface polymer brush border in lubrication of biological joints(Springer Science and Business Media LLC, 2021)Although experimental evidence has suggested that the polymer brush border (PBB) on the cartilage surface is important in regulating fluid permeability in the contact gap, the current theoretical understanding of joint lubrication is still limited. To address this research gap, a multiscale cartilage contact model that includes PBB, in particular its effect on the fluid permeability of the contact gap, is developed in this study. Microscale modeling is employed to estimate the permeability of the contact gap. This permeability is classified into two categories: For a gap size > 1 µm, the flow resistance is assumed to be dominated by the cartilage roughness; for gap size < 1 µm, flow resistance is assumed to be dominated by the surface polymers extending beyond the collagen network of the articular cartilage. For gap sizes of less than 1 µm, the gap permeability decreases exponentially with increasing aggrecan concentration, whereas the aggrecan concentration varies inversely with the gap size. Subsequently, the gap permeability is employed in a macroscale cartilage contact model, in which both the contact gap space and articular cartilage are modeled as two interacting poroelastic systems. The fluid exchange between these two media is achieved by imposing pressure and normal flux continuity boundary conditions. The model results suggest that PBB can substantially enhance cartilage lubrication by increasing the gap fluid load support (e.g., by 26 times after a 20-min indentation compared with the test model without a PBB). Additionally, the fluid flow resistance of PBB sustains the cartilage interstitial fluid pressure for a relatively long period, and hence reduces the vertical deformation of the tissue. Furthermore, it can be inferred that a reduction in the PBB thickness impairs cartilage lubrication ability.
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ItemA probabilistic approach for modelling bone fracture healing under Ilizarov circular fixator(WILEY, 2021-07)Bone fracture treatments using Ilizarov circular fixator (ICF) involve dealing with uncertainties about a range of critical factors that control the mechanical microenvironment of the fracture site such as ICF configuration, fracture gap size, physiological loading etc. To date, the effects of the uncertainties about these critical factors on the mechanical microenvironment of the fracture site have not been fully understood. The purpose of this study is to tackle this challenge by using computational modelling in conjunction with engineering reliability analysis. Particularly, the effects of uncertainties in fracture gap size (GS), level of weight-bearing (P), ICF wire pretension (T) and wire diameter (WD) on the fracture site mechanical microenvironment at the beginning of the reparative phase of healing was investigated in this study. The results show that the mechanical microenvironment of fracture site stabilised with ICF is very sensitive to the uncertainties in P and GS. For example, an increase in the coefficient of variation of P (COVP ) from 0.1 to 0.9 (i.e., an increase in the uncertainty in P) could reduce the probability of achieving a favourable mechanical microenvironment within the fracture site (i.e., Probability of Success, PoS) by more than 50%, while an increase in the coefficient of variation of GS (COVGS ) from 0.1 to 0.9 could decrease PoS by around 30%. In contrast, an increase in the uncertainties in T and WD (COV increase from 0.1 to 0.9) has little influence on the fracture site mechanical microenvironment (PoS changes <5%).