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The concept and technology of a digital twin, which represent a replica of a real object in a virtual space called Industry 4.0, are widely used across all industries and purposes. Similarly, in the architecture, engineering, and construction (AEC) industries, there is an urgent need to develop a technology called BIM, a form of digital twin based on 3D models, for the purpose of improving productivity and reducing costs. Bridge structures are required to be safe, reliable, and durable, and various research studies have been conducted on maintenance and repair strategies and their development by fusing health monitoring and digital twins. In this study, we explore the development of digital twin–BIM technology and demonstrate its various applications for an existing bridge structure where the implementation of health monitoring is planned. Moreover, we evaluate the characteristics of the structural performance of the bridge structure using digital twin–BIM technology.

The construction of new renewable energy infrastructures and the development of new ocean resources continues to proceed apace. In this regard, the increasing size and capacity of offshore wind turbines demands that the size of their accompanying supporting marine structures likewise increase. The types of marine structures utilized for these offshore applications include gravity base, monopile, jacket, and tripod structures. Of these four types, monopile structures are widely used, given that they are comparatively easy to construct and more economical than other structures. However, constant exposure to harsh cyclic environmental loads can cause material deterioration or the initiation of fatigue cracks, which can then lead to catastrophic failures. In this paper, a 3D fatigue finite element analysis was performed to predict both the fatigue life and the crack initiation of a welded monopile substructure. The whole analysis was undertaken in three steps. First, a 3D non-steady heat conduction analysis was used to calculate the thermal history. Second, a thermal load was induced, as an input in 3D elastoplastic analysis, in order to determine welding residual stresses and welding deformation. Finally, the plastic strain and residual stress were used as inputs in a 3D fatigue FE analysis in order to calculate fatigue crack initiation and fatigue life. The 3D fatigue finite element analysis was based on continuum damage mechanics (CDM) and elastoplastic constitutive equations. The results obtained from the 3D fatigue finite element analysis were compared with hot spot stresses and Det Norske Veritas (DNV-GL) standards.

The present case study, using computer modeling technology, is to investigate the process of ice melting (de-icing) on iced ground wires due to current flowing through the ground wire. Using the AC model, the time course of heating of the given ground wire has been determined, and treating the results as input to the thermal model, the ice melting process has also been investigated by finite element thermal analysis. After comparing the elements by computer analysis to laboratory measurements, the results obtained were validated with numerical analysis.

This paper investigates the ability of steel fibers to enhance the short-term behavior and flexural performance of realistic steel fiber-reinforced concrete (SFRC) structural members with steel reinforcing bars and stirrups using nonlinear 3D finite element (FE) analysis. Test results of 17 large-scale beam specimens tested under monotonic flexural four-point loading from the literature are used as an experimental database to validate the developed nonlinear 3D FE analysis and to study the contributions of steel fibers on the initial stiffness, strength, deformation capacity, cracking behavior, and residual stress. The examined SFRC beams include various ratios of longitudinal reinforcement (0.3%, 0.6%, and 1.0%) and steel fiber volume fractions (from 0.3% to 1.5%). The proposed FE analysis employs the nonlinearities of the materials with new and established constitutive relationships for the SFRC under compression and tension based on experimental data. Especially for the tensional response of SFRC, an efficient smeared crack approach is proposed that utilizes the fracture properties of the material utilizing special stress versus crack width relations with tension softening for the post-cracking SFRC tensile response instead of stress–strain laws. The post-cracking tensile behavior of the SFRC near the reinforcing bars is modeled by a tension stiffening model that considers the SFRC fracture properties, the steel fiber interaction in cracked concrete, and the bond behavior of steel bars. The model validation is carried out comparing the computed key overall and local responses and responses measured in the tests. Extensive comparisons between numerical and experimental results reveal that a reliable and computationally-efficient model captures well the key aspects of the response, such as the SFRC tension softening, the tension stiffening effect, the bending moment–curvature envelope, and the favorable contribution of the steel fibers on the residual response. The results of this study reveal the favorable influence of steel fibers on the flexural behavior, the cracking performance, and the post-cracking residual stress.

Hallux valgus is a foot pathological condition showing a lateral deviation of the first phalange and medial deviation of the first metatarsal. The purpose of the current study was to evaluate a longitudinal effect of minimalist footwear running protocol for a mild/moderate hallux valgus patient. The computer tomography (CT) images from a male hallux valgus (HV) patient were respectively scanned pre and post 12-week minimalist footwear running intervention. The pre and post -intervention foot finite element (FE) models were developed from the foot three-dimensional geometries manually segmented via the MIMICS 21.0. The post-process with SolidWorks 2019 was conducted for model assembly, consisting of 24 bones, 22 cartilages, five plantar fascia, and lumped encapsulated soft tissue. The foot FE models were solved in ANSYS Workbench 2020 R1 package. The FE models were validated against the plantar pressure (pre: 0.146 MPa vs 0.155 MPa, and post: 0.156 MPa vs 0.17 MPa) and vertical displacements (pre: 2.6 mm vs 2.4 ± 0.4 mm, and post 1.1 mm vs 1.3 ± 0.4 mm) of navicular measured from experiments. The first metatarsophalangeal joint showed varus realignment and the von Mises stress in the first metatarsal and the second metatarsal decreased 72.1% and 51.2% compared with pre-intervention (M1: 4.41 MPa and M2: 4.18 MPa). This framework investigated the shape adjustment and functional recovery in the mild/moderate HV deformity, which may provide references and implications for future studies with a larger cohort.

An Fe-based shape memory alloy (Fe-SMA) is an alloy that has a characteristic of being able to return to its original shape when heated, even after undergoing plastic deformation. Many researchers have conducted various studies to understand the effectiveness of using Fe-SMA in concrete structures. Most studies selected the heating temperature of Fe-SMA to be below 160 °C based on the logic that concrete hydrolyzes when its temperature exceeds 160 °C. However, because the recovery stress of Fe-SMA increases as the heating temperature increases, it is expected that greater prestress could be introduced when the heating temperature is high. In this study, to confirm this, a numerical study was conducted to evaluate the effect of Fe-SMA heating temperature on the flexural performance of concrete members through finite element (FE) analysis. The analysis results showed that the initial crack load of the specimen increased by about 89% to 173% as the heating temperature of Fe-SMA increased. In addition, the accuracy of the proposed FE model (FEM) was verified through experiments. As a result, it was confirmed that the proposed FE analysis can relatively accurately predict the failure mode and load–displacement relationship of the specimen.

Fifteen slender rectangular reinforced concrete (RC) columns with longitudinal glass fiber-reinforced polymer (FRP) bars were tested under compression in this paper. Results showed that all columns with varying length-to-depth ratios and eccentricity ratios failed by concrete crushing, and no rupture of FRP bars was experienced. Moreover, validated nonlinear finite element model was used to perform a detailed parametric study of 27,000 FRP-RC columns using Opensees. Based on parametric analysis results in conjunction with the moment magnifier method, a refined design equation of the effective flexural stiffness EI was then statistically derived to determine the second-order bending moments. On this basis, a design approach was proposed for slender FRP-RC rectangular columns, in which the contribution of FRP bars in compression to the strength of sections was taken into account. The proposed approach is more consistent and accurate than existing design methods by comparing their predictions with available experimental results of 46 columns. Keyword: design approach; effective flexural stiffness; fiber-reinforced polymer (FRP) bars; finite element (FE) analysis; rectangular column; reinforced concrete.

The use of fibers as mass reinforcement to delay cracking and to improve the strength and the post-cracking performance of reinforced concrete (RC) beams has been well documented. However, issues of common engineering practice about the beneficial effect of steel fibers to the seismic resistance of RC structural members in active earthquake zones have not yet been fully clarified. This study presents an experimental and a numerical approach to the aforementioned question. The hysteretic response of slender and deep steel fiber-reinforced concrete (SFRC) beams reinforced with steel reinforcement is investigated through tests of eleven beams subjected to reversal cyclic loading and numerical analysis using 3D finite element (FE) modeling. The experimental program includes flexural and shear-critical SFRC beams with different ratios of steel reinforcing bars (0.55% and 1.0%), closed stirrups (from 0 to 0.5%), and fibers with content from 0.5 to 3% per volume. The developed nonlinear FE numerical simulation considers well-established relationships for the compression and tensional behavior of SFRC that are based on test results. Specifically, a smeared crack model is proposed for the post-cracking behavior of SFRC under tension, which employs the fracture characteristics of the composite material using stress versus crack width curves with tension softening. Axial tension tests of prismatic SFRC specimens are also included in this study to support the experimental project and to verify the proposed model. Comparing the numerical results with the experimental ones it is revealed that the proposed model is efficient and accurately captures the crucial aspects of the response, such as the SFRC tension softening effect, the load versus deformation cyclic envelope and the influence of the fibers on the overall hysteretic performance. The findings of this study also reveal that SFRC beams showed enhanced cyclic behavior in terms of residual stiffness, load-bearing capacity, deformation, energy dissipation ability and cracking performance, maintaining their integrity through the imposed reversal cyclic tests.

In this paper, a FE formulation for nonlinear vibration of fully geometrically exact Timoshenko beams is derived. Firstly, the strong form of the governing equation of motion is obtained without any approximation. Next, the weak relations are used to derive the FE formulation. To obtain the vibration response, a direct integration method is employed to solve highly nonlinear formulation for geometrically exact beams. Finally, some examples are investigated, and very good results with analytical solutions available in the literature are achieved. The results show that the formulation presented in this paper can predict the vibration response of the Timoshenko beam with high accuracy. Moreover, investigating the effect of parameters shows that increasing the length parameter leads to increasing natural frequencies. Besides, the frequency value increases when the amplitude of vibration increases. Furthermore, adding an axial spring can lead to asymptotic behavior in vibration response of the fully exact Timoshenko beams.