• Steel and Composite Structures
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• v.41 no.5
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• pp.637-648
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• 2021

Nowadays, one of the practical, fast and easy ways to strengthen steel elements is the use of Carbon Fiber Reinforced Polymer (CFRP). Most previous research in the CFRP strengthening of steel members has carried out on straight steel members. The main difference between horizontal curved beams and straight beams under vertical load is the presence of torsional moment in the horizontal curved beams. In the other words, the horizontal curved beams are analyzed and designed for simultaneous internal forces included bending moment, torsional moment, and shear force. The horizontal curved steel beams are usually used in buildings, bridges, trusses, and others. This study explored the effect of the CFRP strengthening on the behavior of the horizontal curved square hollow section (SHS) steel beams. Four specimens were analyzed, one non-strengthened curved steel beam as a control column and three horizontal curved steel beams strengthened using CFRP sheets (under concentrated load and uniform distributed load). To analyze the horizontal curved steel beams, three dimensional (3D) modeling and nonlinear static analysis methods using ANSYS software were applied. The results indicated that application of CFRP sheets in some specific locations of the horizontal curved steel beams could increase the ultimate capacity of these beams, significantly. Also, the results indicated when the horizontal curved steel beams were under distributed load, the increase rate in the ultimate capacity was more than in the case when these beams were under concentrated load.

• Journal of Korean Society of Steel Construction
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• v.9 no.1 s.30
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• pp.51-63
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• 1997

Highly curved steel-box bridges are usually constructed as ramp structures for the highway interchange and metropolitan elevated highway junction, but a number of these bridges are deteriorated and damaged to a significant degree due to heavy traffic. The main objective of the study is to develop a practical reliability-based assessment of safety and residual load carrying-capacity of existing curved steel-box ramp bridges. In the paper, for the realistic assessment of safety and residual load carrying-capacity of deteriorated and/or damaged curved steel-box bridges, an interactive non-linear limit state model is formulated based on the von Mises's combined stress yield criterion. It is demonstrated that the proposed model is effective for the assessment of reliability-based safety and the evaluation of residual load carrying-capacity of curved steel-box bridges. In addition, this study comparatively shows the applicability of various reliability analysis methods, and suggests a practical and effective one to be used in practice.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.511-518
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• 2005

The behavior of steel curved bridges is more complicated than straight bridges, thus the analysis, design and construction process of curved bridges require much more attention. In design of curved bridges, the grillage analysis using general structural analysis program or special program is mainly used. Comparative study in coherence between these analytical results and actual behavior of curved bridges has been rarely conducted. To study the behaviour of curved bridges and verify the current design method, field measurements and analyses using general structural analysis program and 3-D refined analysis program were carried out for simple and continuous bridges in this study. The study focused on the behavior of curved steel bridges during construction. Measured and analytical results had quantitative difference mutually, but there were qualitatively similar. Stress variations in transverse direction of flange were observed and grillage analysis models yielded more conservative values than 3-D refined analysis models.

• Steel and Composite Structures
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• v.9 no.4
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• pp.325-348
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• 2009

This paper is concerned with steel-concrete composite plate girders curved in plan. At the design stage these girders are assumed sometimes to act independent of the deck slabs resting on them in order to simplify the analysis. The advantage of composite action between the steel girders and concrete deck is not utilized. Finite element modeling of such composite action in plate girders is considered in this paper. Details of the finite element modeling and the non-linear analysis of the girders are presented along with the results obtained. Tension field action in the web panels similar to those observed in the straight plate girders is also noticed in these girders. Finite element and experimental results in respect of curved steel plate girders and straight composite plate girders tested by other researchers are presented first to assess the accuracy of the modeling. Effects of parameters such as curvature, steel flange width and web panel width that affect the behavior of composite girders are then considered in the analyses. An approximate method to predict the ultimate strength of horizontally curved composite plate girders is also presented.

• Steel and Composite Structures
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• v.17 no.6
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• pp.951-965
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• 2014

Point bending is commonly used for cambering and curving steel girders to large radii. In this system, a hydraulic ram or press is used to apply concentrated loads at selected points to obtain the required vertical (cambering) or horizontal (curving) curved profile from induced permanent deformations. This paper derives closed form solutions that relate loads to permanent deformations for horizontally curving wide flange steel beams based on their post-yield response. These solutions are presented in a parametric form to identify the relationship between key variables and their impact on the accuracy of the curving operation. It is shown that point bending could yield parabolic curved profiles that are within 1% of a desired circular curve if the span length to radius of curvature ratio (L / R) is less than 1.5 and the point loads are spaced at one third the beam length. Safe limits are then established on loads, strains and curvatures to avoid damaging the steel section. This leads to optimization of the point bending operation for inducing a circular profile in wide flange steel beams of any size.

• Structural Engineering and Mechanics
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• v.34 no.3
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• pp.395-398
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• 2010

• Steel and Composite Structures
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• v.44 no.1
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• pp.17-31
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• 2022

This investigation studies the characteristics of wave dispersion in sigmoid functionally graded (SFG) curved beams lying on an elastic substrate for the first time. Homogenization process was performed with the help of sigmoid function and two power laws. Moreover, various materials such as Zirconia, Alumina, Monel and Nickel steel were explored as curved beams materials. In addition, curved beams were rested on an elastic substrate which was modelled based on Winkler-Pasternak foundation. The SFG curved beams' governing equations were derived according to Euler-Bernoulli curved beam theory which is known as classic beam theory and Hamilton's principle. The resulted governing equations were solved via an analytical method. In order to validate the utilized method, the obtained outcomes were compared with other researches. Finally, the influences of various parameters, including wave number, opening angle, gradient index, Winkler coefficient and Pasternak coefficient were evaluated and indicated in the form of diagrams.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.94-109
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• 1998

The purpose of this study was to evaluate the effect of materials and sizes of files on canal transportation in a curved canal. The stress and the strain energy of files of two kinds of materials (stainless steel and NiTi) and five sizes (No. 20, 25, 30, 35 and 40) in a curved canal were analyzed by a finite element program, NASTRAN. Curved canals in transparent resin blocks were instrumented with the 10 kinds of files, and the degree of canal transportation obtained by double exposure technique of photography was compared with the analysis by the finite element method. The results were as follows : 1. The stress of a file in a curved canal increased from the file body to the file tip. 2. The stress of a stainless steel file was about 2.5 times greater than that of a same-sized NiTi file. 3. The stress distributions of files of an identical material were the same, and the strain energies of files of an identical material increased as the size of files increased. 4. The strain energy of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file. 5. The degree of canal transportation by a stainless steel file was greater than that by a same-sized NiTi file. The degree of canal transportation generally increased as the size of a file increased. 6. The degree of canal transportation of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.428-433
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• 1999

In this study, new finite clement formulations are carried out to analyze the distortion of the curved steel box girders which are susceptible to the torsional loading. For the exact analysis of curved box girders, additional degrees of freedom are added besides the conventional 6 degrees of freedom of general-purpose finite analysis programs, which are torsional warping, distortional warring, and distortion. New formulations were coded into a computer programs. Several numerical examples were presented to demonstrate the validity of developed program.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.401-408
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• 2001

The main objective of this study is to analyze the distortion of curved steel box girders. For the distortional analysis of steel box girders, two approaches are presented. One is the development of approximate formulas obtained by applying Ritz method. The other is the formulation of stiffness matrix which is derived from the exact solution of the differential equation for distortion. Distortional analysis is carried out by utilizing 3-dimensional elements of a structural analysis computer program (SAP2000). The present analysis focuses on the distortional stress and the effects of the diaphragm. The results of several example cases are compared with those by the Nakai, Sakai, Heins, and Oleinik's theory and get the effect of diaphragm spacing on the distortional warping stress of the curved steel box girder.