• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.2
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• pp.137-144
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• 2020

The purpose of this study is to experimentally evaluate the effect of improving seismic performance by applying the details of seismic reinforcement to the reinforced concrete frame with non-seismic details while maintaining the original opening shape. In this study, based on CF specimens with specific seismic details, a total of four full scale specimens were designed and fabricated. The main variables are the width and spacing of steel dampers installed in the upper and lower parts of seismic reinforcement details, and the presence or absence of torsion springs installed in the hinges. As a result of the test, it was evaluated to be helpful for seismic retrofit and opening isolation of steel dampers installed at the upper and lower parts of the seismic reinforcement details and torsion springs installed at the joints. In particular, CFR2S specimens with torsion springs showed the best performance in terms of strength, stiffness and energy dissipation capacity with increasing displacement angle.

• Earthquakes and Structures
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• v.12 no.2
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• pp.201-211
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• 2017

This paper experimentally investigates the effect of yield strength of reinforcing bars and stirrups on the seismic performance of reinforced concrete (RC) circular piers. Reversed cyclic loading tests of nine-large scale specimens with longitudinal and transverse reinforcement of different yield strengths (varying between HRB335, HRB500E and HRB600 rebars) were conducted. The test parameters include the yield strength and amount of longitudinal and transverse reinforcement. The results indicate that the adoption of high-strength steel (HSS) reinforcement HRB500E and HRB600 (to replace HRB335) as longitudinal bars without reducing the steel area (i.e., equal volume replacement) is found to increase the moment resistance (as expected) and the total deformation capacity while reducing the residual displacement, ductility and energy dissipation capacity to some extent. Higher strength stirrups enhance the ductility and energy dissipation capacity of RC bridge piers. While the product of steel yield strength and reinforcement ratio ($f_y{\rho}_s$) is kept constant (i.e., equal strength replacement), the piers with higher yield strength longitudinal bars are found to achieve as good seismic performance as when lower strength bars are used. When higher yield strength transverse reinforcement is to be used to maintain equal strength, reducing bar diameter is found to be a better approach than increasing the tie spacing.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.47-55
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• 2014

As increasing number of large-size earthquake around Korean peninsula, many interests have been focused to the earthquake strengthening of existing structures. The brittle fracture of Non-seismic designed columns lead to full collapse of the building. In the past, cross-sectional extension method, a steel plate reinforcing method and fiver-reinforced method are applied to Seismic Rehabilitation Technique mainly. However, the reinforcement methods have drawbacks that induce physical damage to structures, large space, long duration time. So, in this study, performance evaluation of previously developed FRP seismic reinforcement which do not induce physical damage and short duration time was enforced. The specimens were constructed with 80% downscale. FRP seismic reinforcement are manufactured of glass fiber or aluminum plate with holes and glass fiber. From the experiment results, seismic performance of specimens which reinforced with FRP seismic reinforcement were increased.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.4
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• pp.193-203
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• 2024

Existing reinforced concrete (RC) building frames constructed before the seismic design was applied have seismically deficient structural details, and buildings with such structural details show brittle behavior that is destroyed early due to low shear performance. Various reinforcement systems, such as fiber-reinforced polymer (FRP) jacketing systems, are being studied to reinforce the seismically deficient RC frames. Due to the step-by-step modeling and interpretation process, existing seismic performance assessment and reinforcement design of buildings consume an enormous amount of workforce and time. Various machine learning (ML) models were developed using input and output datasets for seismic loads and reinforcement details built through the finite element (FE) model developed in previous studies to overcome these shortcomings. To assess the performance of the seismic performance prediction models developed in this study, the mean squared error (MSE), R-square (R²), and residual of each model were compared. Overall, the applied ML was found to rapidly and effectively predict the seismic performance of buildings according to changes in load and reinforcement details without overfitting. In addition, the best-fit model for each seismic performance class was selected by analyzing the performance by class of the ML models.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1143-1148
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• 2011

In this study, seismic structural reinforcement are carried out, based on the estimated seismic performance of underground box structures in urban railway, and displacement based design method was developed to enhance seismic performance of structures. New seismic reinforcement design method is proposed and compared with existing design methods. And presented an overview of the developed design methodology through a design example to verify the validity of that methods.

• Journal of Korean Society of Disaster and Security
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• v.13 no.1
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• pp.13-23
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• 2020

In 2005, Urban railway seismic design was introduced in Rep. Of Korea, and many studies on seismic performance evaluation and reinforcement methods were conducted. In accordance with the Enforcement Decree of the Earthquake Disaster Countermeasures Act issued in March 2009, during April 2010 to October 2013, some of local governments established detailed evaluation and reinforcement measures for seismic performance of the urban railway underground structure. Afterwards, the seismic performance reinforcement of the existing urban railway structures was conducted for the sections that a long period of used until the end of 2018, and the reinforcement works are carried out by various methods using the previously studied methods. However, various reinforcing materials and construction methods using have been studied, but the classification research on the construction methods currently applied to reinforcement construction of urban railways is insufficient. The purpose of study is to analysis the cases currently applied to seismic reinforcement construction and to show the characteristics of each construction method, the reasons for its application and problems.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.3
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• pp.117-124
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• 2014

Diagonal reinforced coupling beam of coupled shear walls can provide sufficient strength and stiffness to resist lateral force. However, the reinforcement details for coupling beams required by ACI 318 (2011) are difficult to construct because of the reinforcement congestion and confined interior area. This study presents experimental results about the seismic performance of coupling beams having bundled diagonal reinforcement to improve the workability. Experiments were conducted using half scaled precast coupling beams having an aspect ratio of 2.0. It was observed that the bundled diagonal reinforced coupling beams can develop seismic performance similar to the coupling beams with requirement details specified in ACI 318 (2011).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.521-526
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• 2002

The seismic performance of structural walls subjected to the cyclic lateral loads are influenced by various factors, like sectional shape, aspect ratio, reinforcement ratio, arrangement of reinforcement, and axial load ratio etc. In this research, reinforced concrete structural walls with the T-shaped cross section were selected. The seismic performance of T-shaped wall was affected by the many (actors because T-shaped wall is irregular wall composed to two rectangular walls. Especially the seismic performance of T-shaped wall varies with the flange condition and the various factors including the flange condition were determined. Therefore, the objective of this study is to understand the factors to improve seismic performance of RC T-shaded tv using sectional analysis.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.21-31
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• 2016

This study investigates the seismic performance of new hollow reinforced concrete (RC) bridge piers with triangular reinforcement details. The developed triangular reinforcement details are economically feasible and rational, and facilitate shorter construction periods. We tested a model of new hollow RC bridge piers with triangular reinforcement details under a constant axial load and a quasi-static, cyclically reversed horizontal load. We used a computer program, Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST), for analysis of RC structures. The used numerical method gives a realistic prediction of seismic performance throughout the loading cycles for several hollow pier specimens investigated. As a result, developed triangular reinforcement details for material quantity reduction was equal to existing reinforcement details in terms of required performance.

• Earthquakes and Structures
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• v.7 no.3
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• pp.251-269
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• 2014

To investigate the seismic performance and to obtain quantitative parameters for the requirement of performance-based bridge seismic design approach, 12 reinforced concrete (RC) hollow rectangular bridge column specimens were tested under constant axial load and cyclic bending. Parametric study is carried out on axial load ratio, aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. The damage states of these column specimens were related to engineering limit states to determine the quantitative criteria of performance-based bridge seismic design. The hysteretic behavior of bridge column specimens was simulated based on the fiber model in OpenSees program and the results of the force-displacement hysteretic curves were well agreed with the experimental results. The damage states of residual cracking, cover spalling, and core crushing could be well related to engineering limit states, such as longitudinal tensile strains of reinforcement or compressive strains of concrete, etc. using cumulative probability curves. The ductility coefficient varying from 3.71 to 8.29, and the equivalent viscous damping ratio varying from 0.19 to 0.31 could meet the requirements of seismic design.