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One of the most challenging elements of modeling the behaviour of reinforced concrete (RC) walls is combining realistic material models that can capture the observable behaviour of the physical system. Experiments with realistic loading rates and pressures reveal that steel and concrete display complicated nonlinear behaviour that is challenging to represent in a single constitutive model. To investigate the response of a reinforced concrete structure subjected to dynamic loads, this paper's study is based on many different material models to assess the advantages and disadvantages of the models on 2D and 3D RC walls using the LS-DYNA program. The models consisted of the KCC model and the CDP model, which represented plasticity and distinct tensile/compressive damage models, and the Winfrith model, which represented plasticity and the smeared crack model. Subsequently, the models' performances were assessed by comparing them to experimental data from reinforced concrete structures, in order to validate the accuracy of the overall behaviour prediction. The Winfrith model demonstrated satisfactory results in predicting the behaviour of 2D and 3D walls, including maximum strength, stiffness deterioration, and energy dissipation. The method accurately predicted the maximum strength of the Winfrith concrete model for the 2D wall with an error of 9.24% and for the 3D wall with errors of 3.28% in the X direction and 5.02% in the Y direction. The Winfrith model demonstrated higher precision in predicting dissipation energy for the 3D wall in both the X and Y directions, with errors of 6.84% and 6.62%, correspondingly. Additional parametric analyses were carried out to investigate structural behaviour, taking into account variables such as concrete strength, strain rate, mesh size, and the influence of the element type.

Cast-in-place anchors are being increasingly used in many applications including building construction, bridge, and power plants. The anchorage to concrete systems are subjected to tensile, shear and combined loads from a variety of loading circumstances including static, dynamic, and shock loading. Despite extensive studies on these systems, reliable numerical models for predicting the behavior of these anchors are still limited. Therefore, this paper investigated the tensile behavior of cast-in-place anchorage to concrete systems, to propose an effective model for reproducing anchorage behavior using finite element (FE) methods. Experiments and code-based models for the anchorage system in tension were used to evaluate the numerical models for cast-in-place anchors in concrete, and the most suitable model, with advantages in accuracy and saving analysis time, was chosen. Finally, the FE model was used to study the tensile capacity and related dynamic increase factor for various strain rates, anchor diameters, and embedment depths., (© 2023. Springer Nature Limited.)

Introduction: The aim of this research was to verify that ultraviolet light (UV)-photofunctionalization improves the success rate and biomechanical stability of miniscrews regardless of length, and to evaluate the comparability of biomechanical stability between UV-photofunctionalized miniscrews with short lengths and untreated miniscrews with conventional lengths., Methods: Eight male beagles (age, 12-15 months; weight, 10-13 kg) received a total of 64 miniscrews, including 7-mm and 4-mm untreated and UV-photofunctionalized, acid-etched miniscrews with the use of a random block design. The cumulative success rates were examined in all studied groups. The insertion and removal torques and screw mobility were measured. Microcomputed tomographic scans and histomorphometric analyses were performed at 8 weeks postoperatively., Results: The success rates of 7-mm UV-untreated and UV-photofunctionalized miniscrews were 87.5% and 100%, respectively, vs 43.8% for the 4-mm UV-untreated and 4-mm UV-photofunctionalized miniscrews. The rates were significantly different in accordance with the length (P <0.001). There were no differences in the insertion and removal torque and screw mobility between groups according to the length or UV treatment. However, the 4-mm UV-untreated miniscrews yielded a mean bone area ratio of 6.35 ± 7.43%, whereas the 7-mm UV-photofunctionalized miniscrew yielded a mean ratio of 32.17 ± 8.34% (P = 0.037)., Conclusions: The UV-photofunctionalization significantly increased the biomechanical stability and led to increased bone and miniscrew contact area in dogs with miniscrews of the same length. However, the most important factor that affected the success rate of the miniscrew was the length., (Copyright © 2020 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)