• Earthquakes and Structures
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• v.9 no.5
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• pp.1045-1067
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• 2015

A performance-based design (PBD) procedure, initially proposed for the seismic design of buildings, is tailored herein to the structural configurations commonly adopted in bridges. It aims at the efficient design of bridges for multiple performance levels (PLs), achieving control over a broad range of design parameters (i.e., strains, deformations, ductility factors) most of which are directly estimated at the design stage using advanced analysis tools (a special type of inelastic dynamic analysis). To evaluate the efficiency of the proposed design methodology, it is applied to an actual bridge that was previously designed using a different PBD method, namely displacement-based design accounting for higher mode effects, thus enabling comparison of the alternative PBD approaches. Assessment of the proposed method using nonlinear dynamic analysis for a set of spectrum-compatible motions, indicate that it results in satisfactory performance of the bridge. Comparison with the displacement-based method reveals significant cost reduction, albeit at the expense of increased computational effort.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.327-334
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• 2002

This paper develops an optimized torsional design method of asymmetric wall structures considering deformation capacities of walls. Contrary to the current torsional provisions, a deformation based torsional design is based on the assumption that stiffness and strength are dependent. Current torsional provisions specify two design eccentricity of stiffness to calculate the design forces of members. But such a methodology leads to an excessive over-strength of some members and an optimal torsional behavior is not ensured. Deformation-based torsional design uses displacement and rotation angle as design parameters and calculates base shear for inelastic torsional response directly. Because optimal torsional behavior can be defined based on the deformation of members, deformation based torsional design procedure can be applied to the optimal and performance-based torsional design. To consider the effect of accidental eccentricity, an over-strength factor is defined. The over-strength factor is determined from performance level, torsional resistance and arrangement of walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.384-387
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• 2003

A new Direct Nonlinear Strut-Tie Model design method performing iterative calculations using secant stiffness was developed. Since basically the proposed design method uses elastic analysis, it has the advantages of convenience and stability in numerical analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it analyzes the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member. Through iterative calculations on the structure preliminary designed with member sizes, the strength and ductility demands of each member can be estimated so that they satisfy the given design strategy, and as the result economical and safe design is achieved.

• Earthquakes and Structures
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• v.5 no.6
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• pp.657-678
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• 2013

For economical earthquake resistant design of cable-stayed bridge tower, the use of energy dissipation systems for the earthquake protection of steel structures represents an alternative seismic design method where the tower structure could be constructed to dissipate a large amount of earthquake input energy through inelastic deformations in certain positions, which could be easily retrofitted after damage. The design of energy dissipation systems for bridges could be achieved as the result of two conflicting requirements: no damage under serviceability limit state load condition and maximum dissipation under ultimate limit state load condition. A new concept for cable-stayed bridge tower seismic design that incorporates sacrificial link scheme of low yield point steel horizontal beam is introduced to enable the tower frame structure to remain elastic under large seismic excitation. A nonlinear dynamic analysis for the tower model with the proposed energy dissipation systems is carried out and compared to the response obtained for the tower with its original configuration. The improvement in seismic performance of the tower with supplemental passive energy dissipation system has been measured in terms of the reduction achieved in different response quantities. Obtained results show that the proposed energy dissipation system of low yield point steel seismic link could strongly enhance the seismic performance of the tower structure where the tower and the overall bridge demands are significantly reduced. Low yield point steel seismic link effectively reduces the damage of main structural members under earthquake loading as seismic link yield level decreases due their exceptional behavior as well as its ability to undergo early plastic deformations achieving the concentration of inelastic deformation at tower horizontal beam.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.2
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• pp.271-278
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• 2000

In this study the effect and applicability of viscoelastic dampers on the seismic reinforcement of steel framed structures are investigated in the context of the performance based design approach. The effect of the damper on dissipating the input seismic energy was investigated with a single degree of freedom system. For analysis models a five-story steel frame subjected to gravity load, a ten-story and twenty-story structure subjected to gravity and wind load were designed. The code-specified design spectrums were constructed for each soil type and performance objective, and artificial ground excitation records to be used in the nonlinear time history analysis were generated based on the design spectrums. Inter-story drift was adopted as the primary performance criterion. According to the analysis results, all model structures turned out to satisfy the performance level for most of the soil conditions except for the soft soil(operational level). It was also found that the seismic performance could be greatly enhanced, and the structures were led to behave elastically by installing viscoelastic dampers on appropriate locations.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.247-257
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• 2002

Recently, performance-based analysis/design methods such as the capacity spectrum method and the direct displacement-based design method were developed. In these methods, the estimation of energy dissipation capacity due to inelastic behavior of RC structures depends on empirical equations which are not sufficiently accurate. On the other hand, in a recent study, a simplified method for evaluating energy dissipation capacity was developed. In the present study, based on the evaluation method, a new seismic design method for flexure-dominated RC walls is developed. In determination of seismic earthquake load, the proposed design method can address variation of the energy dissipation capacity with design parameters such as dimensions and shapes of cross-sections, axial force, and reinforcement ratio and arrangement. The proposed design method is compared with the current performance-based design methods and the applicability of the proposed method is disscussed.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.7_spc
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• pp.561-567
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• 2016

After the Gyeong-ju 9.12 earthquake, we found the necessity of seismic design of nonstructural element is important to reduce damages in view of properties and economic losses. This study focused on the investigation of damages including both properties and human beings. It was found that most of the damages are leaking of water pipe line, rupture of glasses, spalling of roof finishing, cracks of building, and falling from roof. It was also found that the seismic design force of nonstructural elements is taking account into the natural periods, amplification factors, response modification factors to forsee inelastic behaviors. From this studies, it is recommended that more studies are necessary on the seismic design force of nonstructural element.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.11-20
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• 1993

Nonlinear inelastic behavior of an HP saddle shell has been examined by a finite element computer program developed on a Cray Y-MP. The mesh convergence is studied using three progressively refined finite element mesh models, $16{\times}16$, $32{\times}32$ and $64{\times}64$, for the elastic and inelastic analyses. It is shown that the $32{\times}32$ mesh model gives a solution that is very close to that given by the $64{\times}64$ mesh model, thus, showing a convergence. The inelastic analysis shows that the shell has a tremendous capacity to redistribute the stresses. At the ultimate, the concrete cracks and the reinforcement yieldings are spread out all over the shell, indicating that the stress distribution in the shell is approaching that given by the classical membrane theory. The present computer program provides a very useful tool for evaluating the nonlinear ultimate behavior of concrete shells during the design process.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.153-164
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• 2013

In this paper, lateral-torsional buckling(LTB) strength of HSB800 high strength steel plate girder with monosymmetric section under uniform moment was evaluated by nonlinear analysis. The unbraced length in inelastic LTB range was considered for the sections whose smaller or larger flange is in compression with slender, noncompact and compact web. Analyses of SM490 steel girders were first performed with the single-panel and three-panel model to judge the validity of the constructed models by comparing those results with Eurocode 3, AASHTO and AISC codes. By using the same models, LTB strength of HSB800 girder was evaluated and it was found that the sections whose smaller flange is in compression with noncompact flange-slender/noncompact web could not reach the flexural strength of the design codes.

• Structural Engineering and Mechanics
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• v.27 no.5
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• pp.541-554
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• 2007

A simplified yet effective design procedure for viscous dampers was presented based on improved capacity spectrum method in the context of performance-based seismic design. The amount of added viscous damping required to meet a given performance objective was evaluated from the difference between the total demand for effective damping and inherent damping plus equivalent damping resulting from hysteretic deformation of system. Application of the method is illustrated by means of two examples, using Chinese design response spectrum and mean response spectrum. Nonlinear dynamic analysis results indicate that the maximum displacements of structures installed with supplemental dampers designed in accordance with the proposed method agree well with the given target displacements. The advantage of the presented procedure over the conventional iterative design method is also highlighted.