• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2430-2434
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• 2011

Dynamic response is an important consideration because of the possibility of resonance according to KTX running over a railway bridges. When KTX runs over the bridge at critical speed, dynamic response is very depending on damping ratio. Current damping ratio for design of high-speed railway bridges adopted EUROCODE without verification of domestic railway bridges. The purpose of this study is to obtain the coherent damping ratio of high-speed railway bridges. Free vibration signal after KTX runs over a high-speed railway bridge was applied. The representative value from distribution of damping ratio was considered.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.127-145
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• 1999

This paper deals with the development of an approach for evaluating the squash load and rigidity of unprotected concrete filled steel columns at elevated temperatures. The current approach of evaluating these properties is reviewed. It is shown that with a non-uniform temperature distribution, over the composite cross-section, the calculations for the squash load and rigidity are tedious in the current method. A simplified approach is proposed to evaluate the temperature distribution, squash load, and rigidity of composite columns. This approach is based on the model in Eurocode 4 and can conveniently be used to calculate the resistance to axial compression of a concrete filled steel column for any fire resistance time. The accuracy of the proposed approach is assessed by comparing the predicted strengths against the results of fire tests on concrete filled circular and square steel columns. The applicability of the proposed approach to a design situation is illustrated through a numerical example.

• Steel and Composite Structures
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• v.17 no.1
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• pp.105-121
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• 2014

A fundamental limitation of steel structures is the decrease in their load-bearing capacity at high temperatures in fire situations such that structural members may require some additional treatment for fire resistance. In this regard, this paper evaluates the structural stability of fire-resistant steel, introduced in the late 1999s, through tensile coupon tests and proposes some experimental equations for the yield stress, the elastic modulus, and specific heat. The surface temperature, deflection, and maximum stress of fire-resistant steel H-section columns were calculated using their own mechanical and thermal properties. According to a comparison of mechanical properties between fire-resistant steel and Eurocode 3, the former outperformed the latter, and based on a comparison of structural performance between fire-resistant steel and ordinary structural steel of equivalent mechanical properties at room temperature, the former had greater structural stability than the latter through $900^{\circ}C$.

• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.163-182
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• 2014

Safety factors proposed in codes CEB, B.A.E.L 91 and EUROCODE 1 cover a great number of uncertainties; making them inadequate for the assessment of existing structures. Suitable safety factors are established using a probabilistic assessment, once real dimensions, materials strength and existing structures deterioration mechanisms are taken into account. This paper presents a calibration method for safety factors using a typical set of RC bridges in France. It considers the principal stages of corrosion provoked by $CO_2$ and $Cl^-$ penetration and threshold indexes (${\beta}_0$) for existing structures. Reliability indexes are determined by the FORM method in the calibration method.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.228-235
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• 2002

As the response spectrum method generally used in the earthquake resistant design is a linear method, the nonlinear behavior of a structure is to be reflected with a specific factor. Such factors are provided in the "Design Criteria for Roadwaybridges"as response modification factors and in the Eurocode 8, Part 2 as behavior factors. In this study a 5-span steel box bridge with single column piers is selected and the behavior factor is determined. The linear time history analyses are carried out with a simple linear model, where the nonlinear behavior of piers leading to the ductile failure mechanism is considered as predetermined characteristic curves.

• Steel and Composite Structures
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• v.3 no.2
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• pp.111-122
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• 2003

The paper presents a model for analysing the shear-lag effect on the slab of twin-girder composite decks subjected to static actions, support settlements and concrete shrinkage, which are the main actions of interest in composite bridge design. The proposed model includes concrete creep behaviour and shear connection flexibility. The shear-lag in the slab is accounted for by means of a new warping function. The considered actions are then applied to a realistic bridge deck and their effects are discussed. The proposed method is utilised to determine the slab effective widths for three different width-length ratios of the deck. Finally, a comparison between the results obtained with the Eurocode EC4-2 and those obtained with the proposed model is performed.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.83-92
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• 2005

This paper is to evaluate the load carrying capacities of cold-formed steel columns subject to combined axial load and bending moment. A combined strength experiment is carried out using full-scale 24 specimens of lipped channel section with embossment in web. An eccentric axial load is applied in varying member-length and eccentric distance which produces an end-moment of the column. The predictions of the AISI specification and the Eurocode are compared with the experimental results, and it is shown that all of these codes are reasonable on the whole in relation to the experimental results.

• Computers and Concrete
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• v.20 no.2
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• pp.129-143
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• 2017

Seismic design of reinforced concrete (RC) structures requires a certain minimum level of flexural ductility. For example, Eurocode EN1998-1 directly specifies a minimum flexural ductility for RC beams, while Chinese code GB50011 limits the equivalent rectangular stress block depth ratio at peak resisting moment to achieve a certain nominal minimum flexural ductility indirectly. Although confinement is effective in improving the ductility of RC beams, most design codes do not provide any guidelines due to the lack of a suitable theory. In this study, the confinement for desirable flexural ductility performance of both normal- and high-strength concrete beams is evaluated based on a rigorous full-range moment-curvature analysis. An effective strategy is proposed for flexural ductility design of RC beams taking into account confinement. The key parameters considered include the maximum difference of tension and compression reinforcement ratios, and maximum neutral axis depth ratio at peak resisting moment. Empirical formulae and tables are then developed to provide guidelines accordingly.

• Steel and Composite Structures
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• v.24 no.2
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• pp.201-211
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• 2017

This study evaluates the reliability of present European codes in predicting the collapse load of columns made with perforated cold-formed steel (CFS) profiles under combined axial load and bending. To this aim, a series of experimental tests on slender open-section specimens have been performed at varying load eccentricity. Preliminarily, stub column tests have also been performed to calculate the effective section properties of the investigated profile. By comparison of experimental data with code-specified M-N strength domains, the authors demonstrate that present code formulations may underestimate the collapse load of thin-walled perforated open sections. The study is the first step of a wider experimental and numerical study aimed at better describing strength domains of perforated CFS open sections.

• Earthquakes and Structures
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• v.8 no.2
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• pp.401-422
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• 2015

This paper evaluates the effectiveness of three nonlinear static methods for the prediction of the dynamic response of in-plan irregular buildings. The methods considered are the method suggested in Eurocode 8, a method previously proposed by some of the authors and based on corrective eccentricities and a new method in which two pushover analyses are considered, one with lateral forces applied to the centres of mass of the floors and the other with only translational response. The numerical analyses are carried out on a set of refined models of reinforced concrete framed buildings. The response predicted by the nonlinear static analyses is compared to that provided by nonlinear dynamic analyses. The effectiveness of the nonlinear static methods is evaluated in terms of absolute and interstorey displacements.