Infrastructure Engineering - Research Publications
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ItemNo Preview AvailableA Reliability-Based Framework for Damage Accumulation Due to Multiple Earthquakes: A Case Study on Bridges(MDPI, 2023-06)Damage accumulation due to multiple seismic impacts over time has a significant effect on the residual service life of the bridge. A reliability-based framework was developed to make decisions in bridge maintenance activities. The feature of the framework enables quantifying the time-dependent probability of failure of bridges due to the impact of multiple earthquakes and progressive deterioration. To estimate the reliability of the bridge systems, the probability of failure of the bridge was used. Two case studies were utilised to demonstrate how the method can be applied to the real world. Results show that the accumulated damage caused by multiple earthquakes and progressive deterioration significantly impact the remaining useful life of the bridge. Furthermore, the soil conditions predominantly influence the progressive deterioration and reduce the service life of the bridge. Overall, the proposed framework enables the sustainable decision-making process for bridge maintenance activities. The results reveal the necessity of including the combined impact in the bridge maintenance system and that there is a more than 40% increase in the probability of failure, due to the combined effect of progressive deterioration and earthquake impacts, compared to the impact only due to seismic loads for the considered case study bridge.
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ItemNo Preview AvailableLinking Mesoscopic and Macroscopic Aspects of Inclined Self-Weight Sandwich Beams with Functionally Graded Porous Cores Under Moving Loads(WORLD SCIENTIFIC PUBL CO PTE LTD, 2023-11)The surging interest in porous lightweight structures has been witnessed in recent years to pursue material innovations in broad engineering disciplines for sustainable developments and multifunctional proposes. Functionally graded (FG) porous composites represent a novel way to adjust mechanical characteristics by controlling the porosity distributions. However, the further advance in this field is challenged by the scale gap between mesoscopic and macroscopic aspects of porous structural analysis, i.e. how the local cellular morphologies impact the overall behaviors. The purpose of this paper is to bridge this gap by conducting a theoretical investigation on the performance of inclined self-weight sandwich beams with FG porous cores, where Young’s modulus is obtained with representative volume elements (RVEs) in a multiscale modeling study and depends on the cellular morphologies: average cell size and cell wall thickness. The material properties of closed-cell steel foams are adopted in a two-step assessment on target beams, including a static calculation to examine their bending deformations under gravitational loading which are then imported into a forced vibration analysis considering constant and harmonic moving forces. Timoshenko beam theory is used to establish the displacement field, while Ritz and Newmark methods are employed to solve the governing equations in terms of bending, free vibration, and forced vibration. The inclined beams are assumed to rest on a Pasternak foundation, and the corresponding structural responses can be determined based on the specific cell size and cell wall thickness, of which the effects are quantitatively revealed: the stiffness degradation induced from cellular morphologies increases the dynamic deflections, while the corresponding self-weight static deformations are reduced and the fundamental natural frequencies are raised. The influence from geometrical, boundary, and foundation conditions is also discussed to provide a comprehensive overview. This will be valuable for engineers to develop devisable foam-based load-carrying components with enhanced properties.
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ItemNo Preview AvailableFunctionally graded porous structures: Analyses, performances, and applications – A Review(Elsevier, 2023-10-01)Structural innovation incorporating bio-inspired composites poses a fresh angle to develop novel lightweight forms with strengthened mechanical properties, among which a must-discuss topic is porous structures. The introduction of internal pores mimics the natural bones or timbers, makes the density a designable parameter, and opens a new world for researchers and engineers who have been obsessed in a variety of porous structural forms with desired aspects. One of the important trends is the development of functionally graded (FG) porous structures, where internal porosity gradations present significant potential to further enhance the already superior performances. This paper is aimed to review the recent research advances in this field by centring on the adopted mechanical analysis approaches, the obtained findings, and the application opportunities. We first elaborate on the general concepts of FG porous composites as well as the corresponding structural forms. The widely employed theoretical analysis method is subsequently looked at, touching on the nanofiller reinforcement and followed by the details and examples for numerical modelling and mechanical tests. The related artificial intelligence (AI) assisted calculations are also discussed. The fabrication techniques of FG porous specimens, e.g. additive manufacturing (AM), and the foam, lattice, and honeycomb based studies are strategically categorised. The later performance overview highlights the advantages originated from non-uniform cellular morphologies in the overall buckling, bending, vibration, and compressive energy absorption. Finally, the application perspectives in various sectors and future research directions are given. This synopsis enables the readers to grab the big picture of FG porous structures and possibly enlightens the path for future outlook in this scope.
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ItemNo Preview AvailableFlexural strains in a toughened glass panel generated by impact of an ice sphere(PERGAMON-ELSEVIER SCIENCE LTD, 2023-10-01)
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ItemNo Preview AvailableNonlinear Wind-Induced Vibration Behaviors of Multi-tower Suspension Bridges Under Strong Wind Conditions(Springer Nature Singapore, 2023-01-01)Abstract The aerodynamic characteristics of a multispan suspension bridge differ from those of a two-span suspension bridge. In this study we investigated the nonlinear aerodynamic characteristics of the Maanshan Bridge under nonstationary flow using combination quasi-3D finite element (FE) bridge models of 2D nonlinear aerodynamic force models and 3D nonlinear FE bridge models. The developed model predictions were validated by wind tunnel tests involving a 2D sectional stiffness model and 3D full-bridge aeroelastic model. Results showed that the developed model could potentially describe the nonlinear and unsteady aerodynamic effects on the bridge. Furthermore, the flutter behavior of the Maanshan Bridge under uniform flow changed from the stable limit cycle of soft flutter to unstable limit cycle with the disconnection of two hangers at the 1/2L of the right main span, while the flutter behavior of the bridge under turbulence flow could be defined as the fracture failure of the hangers from the 1/2L of the left main span.
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ItemNo Preview AvailableDevelopment of numerical model-based machine learning algorithms for different healing stages of distal radius fracture healing(ELSEVIER IRELAND LTD, 2023-05)BACKGROUND AND OBJECTIVES: Early therapeutic exercises are vital for the healing of distal radius fractures (DRFs) treated with the volar locking plate. However, current development of rehabilitation plans using computational simulation is normally time-consuming and requires high computational power. Thus, there is a clear need for developing machine learning (ML) based algorithms that are easy for end-users to implement in daily clinical practice. The purpose of the present study is to develop optimal ML algorithms for designing effective DRF physiotherapy programs at different stages of healing. METHOD: First, a three-dimensional computational model for the healing of DRF was developed by integrating mechano-regulated cell differentiation, tissue formation and angiogenesis. The model is capable of predicting time-dependant healing outcomes based on different physiologically relevant loading conditions, fracture geometries, gap sizes, and healing time. After being validated using available clinical data, the developed computational model was implemented to generate a total of 3600 clinical data for training the ML models. Finally, the optimal ML algorithm for each healing stage was identified. RESULTS: The selection of the optimal ML algorithm depends on the healing stage. The results from this study show that cubic support vector machine (SVM) has the best performance in predicting the healing outcomes at the early stage of healing, while trilayered ANN outperforms other ML algorithms in the late stage of healing. The outcomes from the developed optimal ML algorithms indicate that Smith fractures with medium gap sizes could enhance the healing of DRF by inducing larger cartilaginous callus, while Colles fractures with large gap sizes may lead to delayed healing by bringing excessive fibrous tissues. CONCLUSIONS: ML represents a promising approach for developing efficient and effective patient-specific rehabilitation strategies. However, ML algorithms at different healing stages need to be carefully chosen before being implemented in clinical applications.
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ItemThermal Transfer Effects of CRTS II Slab Track Under Various Meteorological Conditions(Springer Nature Singapore, 2023-01-01)Abstract With the evolution of climate change, the thermal transfer effects of ballastless track in high-speed railways under complicated environmental conditions becomes increasingly important, governed by a number of meteorological factors, including solar radiation, ambient temperature, wind speed and direction, humidity, and many others (Matias SR, Ferreira PA, Constr Build Mater 322:126445, 2022).
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ItemHarmonic Vibration of Inclined Porous Nanocomposite Beams(Springer Nature, 2023-01-01)This work investigated the linear harmonic vibration responses of inclined beams featured by closed-cell porous geometries where the bulk matrix materials were reinforced by graphene platelets as nanofillers. Graded and uniform porosity distributions combined with different nanofiller dispersion patterns were applied in the establishment of the constitutive relations, in order to identify their effects on beam behavior under various harmonic loading conditions. The inclined beam model comprised of multiple layers and its displacement field was constructed using Timoshenko theory. Forced vibration analysis was conducted to predict the time histories of mid-span deflections, considering varying geometrical and material characterizations. The findings may provide insights into the development of advanced inclined nanocomposite structural components under periodic excitations.
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ItemNo Preview AvailableDepth camera-based model for studying the effects of muscle loading on distal radius fracture healing(PERGAMON-ELSEVIER SCIENCE LTD, 2023-09)BACKGROUND: Distal radius fractures (DRFs) treated with volar locking plates (VLPs) allows early rehabilitation exercises favourable to fracture recovery. However, the role of rehabilitation exercises induced muscle forces on the biomechanical microenvironment at the fracture site remains to be fully explored. The purpose of this study is to investigate the effects of muscle forces on DRF healing by developing a depth camera-based fracture healing model. METHOD: First, the rehabilitation-related hand motions were captured by a depth camera system. A macro-musculoskeletal model is then developed to analyse the data captured by the system for estimating hand muscle and joint reaction forces which are used as inputs for our previously developed DRF model to predict the tissue differentiation patterns at the fracture site. Finally, the effect of different wrist motions (e.g., from 60° of extension to 60° of flexion) on the DRF healing outcomes will be studied. RESULTS: Muscle and joint reaction forces in hands which are highly dependent on hand motions could significantly affect DRF healing through imposed compressive and bending forces at the fracture site. There is an optimal range of wrist motion (i.e., between 40° of extension and 40° of flexion) which could promote mechanical stimuli governed healing while mitigating the risk of bony non-union due to excessive movement at the fracture site. CONCLUSION: The developed depth camera-based fracture healing model can accurately predict the influence of muscle loading induced by rehabilitation exercises in distal radius fracture healing outcomes. The outcomes from this study could potentially assist osteopathic surgeons in designing effective post-operative rehabilitation strategies for DRF patients.