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Interpretation of the Dynamic Response of a Masonry Arch Rail Viaduct Using finite-element modeling

JOURNAL OF ARCHITECTURAL ENGINEERING 2020年第1期26卷

作者： Cocking, Sam Acikgoz, Sinan DeJong, Matthew Univ Cambridge Dept Engn Civil Engn BldgJJ Thompson Ave 7a Cambridge CB3 0FA England Univ Oxford Dept Engn Sci Parks Rd Oxford OX1 3PJ England Univ Calif Berkeley Dept Civil Engn 760 Davis Hall Berkeley CA 94720 USA

Linear-elastic finite-element analysis is sometimes used to assess masonry arch bridges under service loads, despite the limitations of this method. Specifically, linear-elastic analysis can be sensitive to material properties, geometry, and support settlements, while also allowing the development of tensile stresses that may be unrealistic for masonry structures. However, even though linear-elastic methods remain appealing for their simplicity, it is rare to evaluate their output against experimental data. In this paper, detailed strain and displacement monitoring data for a masonry arch viaduct are used to evaluate a series of independently developed linear-elastic simulations of this structure. Although uncertainties in input parameters mean the magnitude of modeling results cannot be presumed accurate, the simulated response pattern was found to agree reasonably well with monitoring data in regions of low damage. However, more damaged regions produced a markedly different local response. Comparisons between the simulations revealed useful conclusions regarding common modeling assumptions, namely the importance of modeling backing material, spandrels, and foundation stiffness, to capture their influence on the arch response.

关键词： Masonry arch finite-element modeling Structural health monitoring

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finite-element modeling of FRP-Confined Noncircular Concrete Columns Using the Evolutionary Potential-Surface Trace Plasticity Constitutive Model for Concrete

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JOURNAL OF COMPOSITES FOR CONSTRUCTION 2023年第1期27卷 04022089-04022089页

作者： Zheng, Bo-Tong Teng, Jin-Guang Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Struct Engn Hong Kong Peoples R China

The compressive behavior of fiber-reinforced polymer (FRP)-confined concrete columns with a noncircular cross section has been investigated through extensive experimental, analytical, and numerical research, but a unified theoretical/numerical approach that can accurately predict both their section-average behavior and local concrete behavior is not yet available. In noncircular columns under axial compression, the concrete is typically under a nonuniform stress state of three-dimensional (3D) compression, with the lateral compressive stresses being the reactive stresses from the confining device (i.e., passive confinement). The authors of the present paper recently developed a plasticity constitutive model for concrete under general 3D compressive stresses, which possesses a potential surface with an evolutionary deviatoric trace that can accurately capture the results of existing compression tests of concrete cubes under nonuniform, passive confinement. This paper explores the application and capability of this evolutionary potential-surface trace (EPT) plasticity constitutive model in finite-element (FE) analysis of FRP-confined square, rectangular, and elliptical plain-concrete columns under concentric compression. The section-average behavior of all the selected noncircular columns predicted by these FE analyses was close to the existing experimental data. The numerical results obtained with the EPT plasticity constitutive model were then examined in detail to achieve an improved understanding of local concrete behavior in FRP-confined noncircular columns.

关键词： FRP Concrete Plasticity constitutive model Noncircular column Nonuniform confinement Axial compression finite-element modeling

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finite-element modeling of Power Cables Using Coordinate Transformations

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IEEE TRANSACTIONS ON MAGNETICS 2024年第3期60卷 1-1页

作者： Piwonski, Albert Dular, Julien Rezende, Rodrigo Silva Schuhmann, Rolf Tech Univ Berlin Theoret Elektrotech D-10587 Berlin Germany CERN TE MPE PE CH-4130 Geneva Switzerland

Power cables have complex geometries in order to reduce their ac resistance. Although there are many different cable designs, most have in common that their inner conductors' cross section is divided into several electrically insulated conductors, which are twisted over the cable's length (helicoidal symmetry). In previous works, we presented how to exploit this symmetry by means of dimensional reduction within the H-phi formulation of the eddy current problem. Here, the dimensional reduction is based on a coordinate transformation from the Cartesian coordinate system to a helicoidal coordinate system. This contribution focuses on how this approach can be incorporated into the magnetic vector potential-based $\mathrm {A}-v$ formulation.

关键词： Coordinate transformations dimensional reduction eddy currents finite-element modeling magnetic vector potential formulation power cables tree-cotree gauging

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Intensity and region-of-interest-based finite-element modeling of brain deformation

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International Congress Series 2004年第C期1268卷 373-377页

作者： Shi, Hongjian Farag, Aly Computer Vision Image Processing Laboratory Electrical Computer Engineering University of Louisville Louisville KY 40292 403 Lutz Hall Building United States

This paper proposes intensity and region-of-interest-based finite-element modeling of brain deformation. The modeling is based on the intensities of voxels within each element and motion analysis of region of interest (ROI) for image-guided minimally invasive surgery (MIS) applications. It is proposed to configure an ROI at the tip of surgical tools instead of the whole brain, so that the FEM is applied only on the ROI, and the maximum nodal displacement outside the ROI is small and in control. The deformed MR image using the proposed finite-element modeling shows better proportion to its original structures. © 2004, Elsevier Science B.V. All rights reserved.

关键词： Brain deformation finite-element modeling Minimal invasive surgery

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Three-Dimensional finite-element modeling and Validation of a Timber-Framed House to Wind Loading

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JOURNAL OF STRUCTURAL ENGINEERING 2017年第9期143卷 04017112-04017112页

作者： Satheeskumar, Navaratnam Henderson, David James Ginger, John David Wang, Chi-Hsiang James Cook Univ Cyclone Testing Stn Townsville Qld 4811 Australia James Cook Univ Coll Sci & Engn Townsville Qld 4811 Australia CSIRO Land & Water Bayview Dr Clayton Vic 3168 Australia

This paper presents a three-dimensional (3D) finite-element model (FEM) of part of a contemporary timber-framed house for assessing the load sharing and contribution of lining elements to load sharing. Assembled with intercomponent connections (i.e., batten-to-cladding connections, batten-to-truss connections, and roof-to-wall connections), the model consists of structural frame elements (e.g., trusses, battens, metal roof cladding, top plates, bottom plates, and wall studs) and lining elements (e.g., ceiling, wall lining, and ceiling cornice). The model analyses agree favorably with results from full-scale structural tests. The FEM shows that adding lining elements decreases the vertical reaction of the roof-to-wall connection by approximately 25%. This validated model provides confidence for assessing the structural response of a range of typical house geometries and materials including the effects of construction defects to wind loads. (C) 2017 American Society of Civil Engineers.

关键词： Wind effects finite-element modeling Timber-framed structure Wind effects Load sharing

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Time-Dependent Monitoring and modeling of I-35W St. Anthony Falls Bridge. II: finite-element modeling

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JOURNAL OF BRIDGE ENGINEERING 2017年第7期22卷

作者： Hedegaard, Brock D. French, Catherine E. W. Shield, Carol K. Univ Wisconsin Dept Civil & Environm Engn Madison WI 53706 USA Univ Minnesota Dept Civil Environm & Geoengn Minneapolis MN 55455 USA

Data collected from the monitoring system installed in the St. Anthony Falls Bridge, a posttensioned concrete box girder bridge in Minneapolis, Minnesota, represented a combination of temperature-dependent effects due to daily and seasonal temperature changes and time-dependent effects related to creep and shrinkage of the concrete. In the companion paper of this study, the time-dependent creep and shrinkage effects were isolated from the data, and the rates of the creep and shrinkage were adjusted according to the Arrhenius equation. In this paper, results from finite-element models incorporating a variety of time-dependent provisions were compared with the measured time-dependent behavior. The modeling methodology is discussed extensively, including the procedures for incorporating the segmental construction staging sequence and midspan closure pour. Each of the models provided different predictions, and none were found to provide reliable estimates of the measured results throughout the entire 5-year period of investigation, although this was not unexpected due to the uncertainty inherent in the long-term predictions of the time-dependent behavior of concrete structures. Provisions from several standards with asymptotic creep models underestimated the longitudinal deformations and were found to approach asymptotic creep and shrinkage values before any indication of asymptotic behavior was observed in the measured data, although early-age behavior was accurately captured by these provisions. The shape of available logarithmic creep models appeared to be consistent with the measured data, although these models overestimated the longitudinal deformations of the bridge. The best predictions of the measured data were given by the provisions of a previous model code with an asymptotic creep model that properly accounted for the large volume-to-surface ratio of the bridge. Investigation of the computed vertical deflections showed that for all models the direction of the

关键词： finite-element modeling Creep Shrinkage Posttensioned concrete bridges

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Assessment and Management of Concrete Bridges Supported by Monitoring Data-Based finite-element modeling

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JOURNAL OF BRIDGE ENGINEERING 2014年第6期19卷 05014002-05014002页

作者： Sousa, Helder Bento, Joao Figueiras, Joaquim Univ Porto Lab Concrete Technol & Struct Behav LABEST Fac Engn P-4200465 Oporto Portugal Efacec Capital SA P-4466952 Sao Mamede de Infesta Portugal

The long-term assessment of large and complex civil infrastructures, such as prestressed concrete bridges, based on finite-element (FE) modeling remains a challenging task. The construction process, the influence of erection methods, the characterization of concrete properties, geometric accuracy, and environmental conditions are key factors involved in the development of robust FE models. Data collected using permanently installed monitoring systems is the most reliable strategy to improve such assessments. The availability of monitoring data are increasingly being used in the validation of design assumptions, updating of FE models, and safety factors. In this work, the long-term behavior of a long segmental bridge built in Portugal (Leziria Bridge) is evaluated using FE model updating. The combination of several factors, including (1) the bridge's scale, (2) the monitoring database, (3) the comprehensive scanning of important characteristics of the bridge, and (4) the FE modeling approach, makes this case study unique. Although the sensor trends are satisfactorily predicted, extrapolation of shrinkage and creep models, the influence of interior and exterior environments, and thickness variations of the structural elements are identified as areas for further research.

关键词： Girder bridges Concrete bridges finite element method Shrinkage Creep Databases Structural monitoring Box girder Concrete bridge finite-element modeling Shrinkage and creep

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Influence of material and haptic design on the mechanical stability of intraocular lenses by means of finite-element modeling

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JOURNAL OF BIOMEDICAL OPTICS 2018年第3期23卷 035003-035003页

作者： Remon, Laura Siedlecki, Damian Cabeza-Gil, Iulen Calvo, Begona Univ Zaragoza Fac Ciencias Dept Fis Aplicada Zaragoza Spain Wroclaw Univ Sci & Technol Dept Opt & Photon Visual Opt Grp Wroclaw Poland Univ Zaragoza Escuela Ingn & Arquitectura EINA Aragon Inst Engn Res I3A Maria de Luna S-NCampus Rio Ebro Zaragoza Spain Ctr Invest Biomed Red Bioingn Biomat & Nanomed CI Zaragoza Spain

Intraocular lenses (IOLs) are used in the cataract treatment for surgical replacement of the opacified crystalline lens. Before being implanted they have to pass the strict quality control to guarantee a good biomechanical stability inside the capsular bag, avoiding the rotation, and to provide a good optical quality. The goal of this study was to investigate the influence of the material and haptic design on the behavior of the IOLs under dynamic compression condition. For this purpose, the strain-stress characteristics of the hydrophobic and hydrophilic materials were estimated experimentally. Next, these data were used as the input for a finite-element model (FEM) to analyze the stability of different IOL haptic designs, according to the procedure described by the ISO standards. Finally, the simulations of the effect of IOL tilt and decentration on the optical performance were performed in an eye model using a ray-tracing software. The results suggest the major importance of the haptic design rather than the material on the postoperative behavior of an IOL. FEM appears to be a powerful tool for numerical studies of the biomechanical properties of IOLs and it allows one to help in the design phase to the manufacturers. (c) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： finite-element modeling biomechanical stability haptic design mechanical properties optical performance

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Weak Form Equation-Based finite-element modeling of Viscoelastic Asphalt Mixtures

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JOURNAL OF MATERIALS IN CIVIL ENGINEERING 2016年第2期28卷 04015115-04015115页

作者： Zhang, Yuqing Birgisson, Bjorn Lytton, Robert L. Aston Univ Sch Engn & Appl Sci Birmingham B4 7ET W Midlands England Texas A&M Univ Zachry Dept Civil Engn 3136 TAMUCE TTI Bldg 503 A College Stn TX 77843 USA

The objective of this study is to demonstrate using weak form partial differential equation (PDE) method for a finite-element (FE) modeling of a new constitutive relation without the need of user subroutine programming. The viscoelastic asphalt mixtures were modeled by the weak form PDE-based FE method as the examples in the paper. A solid-like generalized Maxwell model was used to represent the deforming mechanism of a viscoelastic material, the constitutive relations of which were derived and implemented in the weak form PDE module of Comsol Multiphysics, a commercial FE program. The weak form PDE modeling of viscoelasticity was verified by comparing Comsol and Abaqus simulations, which employed the same loading configurations and material property inputs in virtual laboratory test simulations. Both produced identical results in terms of axial and radial strain responses. The weak form PDE modeling of viscoelasticity was further validated by comparing the weak form PDE predictions with real laboratory test results of six types of asphalt mixtures with two air void contents and three aging periods. The viscoelastic material properties such as the coefficients of a Prony series model for the relaxation modulus were obtained by converting from the master curves of dynamic modulus and phase angle. Strain responses of compressive creep tests at three temperatures and cyclic load tests were predicted using the weak form PDE modeling and found to be comparable with the measurements of the real laboratory tests. It was demonstrated that the weak form PDE-based FE modeling can serve as an efficient method to implement new constitutive models and can free engineers from user subroutine programming. (c) 2015 American Society of Civil Engineers.

关键词： Asphalt mixture Viscoelasticity finite-element modeling Weak form partial differential equation (PDE) Master curve Generalized Maxwell model

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Three-Dimensional finite-element modeling of the Thermomechanical Response of GFRP-Reinforced Concrete Slab Strips Subjected to Fire

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JOURNAL OF COMPOSITES FOR CONSTRUCTION 2022年第5期26卷 04022044-04022044页

作者： Duarte, Antonio P. C. Rosa, Ines C. Arruda, Mario R. T. Firmo, Joao P. Correia, Joao R. Univ Lisbon Inst Super Tecn Civil Engn Res & Innovat Sustainabil Av Rovisco Pais 1 P-1049001 Lisbon Portugal

The fire design of reinforced concrete (RC) members with glass fiber-reinforced polymer (GFRP) bars comprising lap splices and cold anchoring zones requires the explicit consideration of the GFRP-concrete bond degradation with temperature;however, few studies in the literature have addressed this issue. This paper presents numerical investigations in which three-dimensional finite-element models were developed to simulate fire resistance tests performed in GFRP-RC slab strips subjected to a fire load and current standards. The slabs comprised continuous and spliced reinforcements, as well as different concrete cover thicknesses and concrete strengths. In the models, the GFRP-concrete interaction was simulated by means of previously calibrated local bond stress-slip laws at different temperatures. This study provided new insights into the fire behavior of GFRP-RC flexural members, confirming that their fire resistance can be drastically reduced when lap splices, designed for ambient temperature conditions, are directly exposed to heat and that even adopting relatively low concrete cover, fire endurances above 120 min can be attained provided that the bars' anchors remain sufficiently cold.

关键词： finite-element modeling GFRP-concrete bond Fire GFRP internal reinforcement GFRP-reinforced concrete Concrete slabs

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