• Steel and Composite Structures
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• v.33 no.4
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• pp.489-507
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• 2019

In order to obtain high bearing capacity and good ductility simultaneously, a structural column with hybrid normal and high strength steel (HNHSS) welded box section has been developed. Residual stress is an important factor that can influence the behaviour of a structural member in steel structures. Accordingly, the magnitudes and distributions of residual stresses in HNHSS welded box sections were investigated experimentally using the sectioning method. In this study, the following four box sections were tested: one normal strength steel (NSS) section, one high strength steel (HSS) section, and two HNHSS sections. Based on the experimental data from previous studies and the test results of this study, the effects of the width-to-thickness ratio of plate, yield strength of plate, and the plate thickness of the residual stresses of welded box sections were investigated in detail. A unified residual stress model for NSS, HSS and HNHSS welded box sections was proposed, and the corresponding simplified prediction equations for the maximum tensile residual stress ratio (${\sigma}_{rt}/f_y$) and average compressive residual stress ratio (${\sigma}_{rc}/f_y$) in the model were quantitatively established. The predicted magnitudes and distributions of residual stresses for four tested sections in this study by using the proposed residual stress model were compared with the experimental results, and the feasibility of this proposed model was shown to be in good agreement.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.325-331
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• 2004

Generally, the buckling of thin-walled structures has studied for rectangular sections or circular sections. Rectangular sections have small stiffness and circular sections have large stiffness when they are compared with rectangular sections for local buckling. But both of them have similar stiffness to column buckling. Therefore in this paper, we are going to analyze the local buckling for the box section with rounded comer and compare with rectangular section. Also we confirm that the rounded comer section has larger local buckling strength than rectangular section.

• Wind and Structures
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• v.7 no.1
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• pp.29-40
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• 2004

This study has focused on aerodynamics for a wind-resistance design about the single and tandem box girder sections to realize a super-long span bridge in the near future. Three-dimensional static analysis of flows around the fundamental single and tandem box girder sections with fairing is carried out by means of the IBTD/FS finite element technique with LES turbulence model. As the results of the analysis, computations have verified aerodynamic characteristics of both sections by the histories of aerodynamic forces, the separation and reattachment flow patterns and the surface pressure distributions. The relationship between the section shapes and the aerodynamic characteristics is also investigated in both sections. And the mechanism about the generation of fluctuating aerodynamic forces is discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1157-1162
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• 2000

Transverse stress and longitudinal crack which are induced by temperature difference in box-girder sections and slab of which box-girder is composed have an important effect on endurance and economical efficiency of bridges. The study on longitudinal behavior of bridges which are subject to thermal load is reflected on the design of bridges. But, the study on transverse behavior of bridges has been performed just recently in foreign countries of finding the cause of longitudinal crack and in Korea, has not been tried in spite of large temperature variance due to geographical condition. This study examines temperature distribution feature in box-girder sections and bridge behavior due to thermal load, with measuring temperature distribution and stress of PSC box-girder bridge which is being constructed actually, and investigates appropriateness of design thermal load of highway bridge design code.

• Steel and Composite Structures
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• v.7 no.6
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• pp.441-456
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• 2007

In literature for thin-walled sections with L, [, +, I, and ${\Box}$- shapes the approximate torsion equations for stiffness are used which were proposed by Bach (Hsu 1984), p.30. New formulae for torsional stiffness of bars with L, [, +, I, and ${\Box}$ cross section valid not only for thin-walled sections are presented in this paper. These formulae are obtained by appropriate polynomial approximation of stiffness results obtained by means of method of fundamental solutions. On the base of obtained results the validity of Bach's formulae are verified when cross section is not thin-walled.

• Structural Engineering and Mechanics
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• v.5 no.1
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• pp.21-32
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• 1997

A new torsional analysis method for multiple cell box based on the Softened Truss Model Theory was developed. This softened truss model unifies shear and torsion to address the problem associated with a torque applied on a box. The model should be very useful for the analysis of a reinforced concrete box under torque, especially for the bridge superstructure with multiple cell box sections.

• Wind and Structures
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• v.12 no.3
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• pp.205-217
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• 2009

Aerodynamic flutter control for long-span cable-supported bridges was investigated based on three basic girder sections, i.e. streamlined box girder section, box girder section with cantilevered slabs and two-isolated-girder section. Totally four kinds of aerodynamic flutter control measures (adding fairings, central-slotting, adding central stabilizers and adjusting the position of inspection rail) were included in this research. Their flutter control effects on different basic girder sections were evaluated by sectional model or aeroelastic model wind tunnel tests. It is found that all basic girder sections can get aerodynamically more stabled with appropriate aerodynamic flutter control measures, while the control effects are influenced by the details of control measures and girder section configurations. The control effects of the combinations of these four kinds of aerodynamic flutter control measures, such as central-slotting plus central-stabilizer, were also investigated through sectional model wind tunnel tests, summarized and compared to the flutter control effect of single measure respectively.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.39-46
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• 1998

This paper is about design for diaphragm of prestressed concrete box bridge using strut-tie model. In this paper, equivalent loads for the diaphragm are computed by considering loading conditions on continuous prestressed concrete box bridge and analyses for both longitudinal section and transverse section of the diaphragm an done by considering the equivalent loading and the prestressing. Based on principal stress trajectory obtained from the analyses, strut-tie model for each sections are constructed. By analyzing the constructed strut-tie model for each sections, the amounts and the locations of reinforcement for the diaphragm are obtained. The application of strut-tie model in this paper shows that the design by soul-tie model for the diaphragm of prestressed concrete box bridges can be rationally performed.

• Steel and Composite Structures
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• v.14 no.2
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• pp.105-120
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• 2013

Flexural behavior of thin walled steel-concrete composite sections as cross sections for beams is investigated by conducting an experimental study supported by applicable analytical predictions. The experimental study consists of testing up to failure, simply supported beams of effective span 1440 mm under two point loading. The test specimens consisted of composite box and channel (with lip placed on tension side and compression side) sections, the behavior of which was compared with companion empty sections. To understand the role of shear connectors in developing the composite action, some of the composite sections were provided with novel simple bar type and conventional bolt type shear connectors in the shear zone of beams. Two RCC beams having equivalent ultimate moment carrying capacities as that of composite channel and box sections were also considered in the study. The study showed that the strength to weight ratio of composite beams is much higher than RCC beams and ductility index is also more than RCC and empty beams. The analytical predictions were found to compare fairly well with the experimental results, thereby validating the applicability of rigid plastic theory to cold-formed steel concrete composite beams.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.127-142
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• 2024

In recent decades, pultruded glass fiber-reinforced polymer (GFRP) members including those of box sections have attracted the attention of researchers. Nevertheless, the lack of uniform and consistent material properties, simplified design methods, and practical design codes have so far been the main barrier for field applications. Consequently, this paper highlights the existing knowledge concerning the flexural behavior of pultruded GFRP profiles and their failure modes. In particulate, it reviews the most commonly accepted design expressions and code provisions addressing the flange local buckling of pultruded GFRP box beams as the most likely failure mode. In addition, the material characterization of GFRP sections is described in detail along with the standard test methods to quantify the material characterization of GFRP laminates. It is shown that the critical flange local buckling stresses of pultruded GFRP box beams can be predicted with reliable accuracy using the expressions promulgated by ASCE (1984) (in which the flange plates are considered simply-supported at web-flange junction) and EUR 27666. The expressions stipulated in ASCE (2010) highly overestimates the critical flange local buckling stresses of GFRP box beams resulting in unconservative predictions.