• Land and Housing Review
• /
• v.3 no.2
• /
• pp.195-202
• /
• 2012

This paper summarizes the seismic performance of two shear walls with different reinforcement details in boundary elements. One is a special shear wall designed by KBC2009 and the other is a shear wall with improved reinforcement details in boundary elements, which is a newly proposed type of special shear wall. Experimental tests under cyclic reversed loading were carried out with two 2/3 scale shear walls which were modelled from the lower part of seismic-resisting shear wall in 22-stories wall-slab apartment building. The experimental results show that seismic performance of shear wall with improved reinforcement details was almost similar to that of special shear wall with respect to the moment-drift ratio. However, energy dissipation capacity and ductility were slightly different. Also, shear wall with improved reinforcement details in boundary elements satisfied the inter-story drift limit of 1.5% from KBC2009.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.2
• /
• pp.1-13
• /
• 2010

This paper proposes an optimal design method for the nonlinear seismic isolated bridge. The probabilities of failure at the pier and the seismic isolator are considered as objective functions for optimal design, and a multi-objective optimization technique is employed to efficiently explore a set of multiple solutions optimizing mutually-conflicting objective functions at the same time. In addition, a stochastic linearization method is incorporated into the multi-objective optimization framework in order to effectively estimate the stochastic responses of the bridge without performing numerous nonlinear time history analyses during the optimization process. As a numerical example to demonstrate the efficiency of the proposed method, the Nam-Han river bridge is taken into account, and the proposed method and the existing life-cycle-cost based design method are both applied for the purpose of comparing their seismic performances. The comparative results demonstrate that the proposed method not only shows better seismic performance but also is more economical than the existing cost-based design method. The proposed method is also proven to guarantee improved performance under variations in seismic intensity, in bandwidth and in the predominant frequency of the seismic event.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2022.11a
• /
• pp.501-503
• /
• 2022

초해상이란 해상도가 낮은 영상을 해상도가 높은 영상으로 합성하는 기술이다. 딥러닝은 영상의 해상도를 높이는 초해상 기술에도 응용되며 실현은 2아4년에 발표된 SRCNN(Super Resolution Convolutional Neural Network) 모델로부터 시작됐다. 이후 오토인코더 (Autoencoders) 구조로는 SRCAE(Super Resolution Convolutional Autoencoders), 합성된 영상을 실제 영상과 통계적으로 구분되지 않도록 강제하는 GAN (Generative Adversarial Networks) 구조로는 SRGAN(Super Resolution Generative Adversarial Networks) 모델이 발표됐다. 모두 SRCNN의 성능을 웃도는 모델들이나 그중 가장 높은 성능을 끌어내는 SRGAN 조차 아직 완벽한 성능을 내진 못한다. 본 논문에서는 SRGAN의 성능을 개선하기 위해 사전 훈련된 특징 추출기(Pre-trained Feature Extractor) VGG(Visual Geometry Group)-19 모델을 변경하고, 기존 모델과 성능을 비교한다. 실험 결과, VGG-19 모델보다 윤곽이 뚜렷하고, 실제 영상과 더 가까운 영상을 합성할 수 있는 모델을 발견할 수 있을 것으로 기대된다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.1
• /
• pp.133-142
• /
• 2013

The shear wall system with coupling beams has been known as an effective means for moderate and high rise buildings up to 40 stories, because this structural system can provide the enhanced lateral stiffness compared to individual shear walls. Typical reinforced concrete coupling beams have difficulties in construction due to complicated reinforcing work on site, and steel coupling beams also have disadvantages in economical point of view because of a large number of stiffeners required for its stability under lateral loading. To overcome these disadvantages in existing coupling beam systems, this study developed the prestressed composite coupling beam with discontinuous webs, which have improved constructability, economic feasibility, and reduced sectional size. The reversed cyclic loading test on two prestressed composite coupling beams with discontinuous webs having different shear reinforcement ratios have been conducted to investigate their structural performances, and test results showed that the proposed composite coupling beams had good seismic performances.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4A
• /
• pp.659-675
• /
• 2006

Recently, significant progress has been made in performance-based engineering methods that rely mainly on nonlinear static seismic analysis procedures. The Capacity Spectrum Method (CSM) and the Displacement Coefficient Method (DCM) are the representative nonlinear static seismic analysis procedures. In order to evaluate the applicability of the procedures to the seismic evaluation and design process of new and existing structures, the accuracy of both CSM and DCM should be evaluated in advance. The accuracy of seismic responses by the nonlinear static procedures is evaluated in comparison with the shaking table test results for the structural wall specimen subjected to the far field and near field earthquakes. Also conducted are comparative studies where the shaking table test results are compared with those from nonlinear dynamic analysis procedures, i.e., Single-Degree-of-Freedom (SDOF), equivalent SDOF and Multi-Degree-of-Freedom (MDOF) systems.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.4
• /
• pp.309-318
• /
• 2013

Abutment-to-pile connection in an integral abutment bridge is vulnerable to lateral displacement induced by thermal movement of the superstructure. However, previous researches have merely focused on the connection. In order to improve the performance of the connection, new abutment-to-pile connection designs were proposed based on quasi-static nonlinear finite element model. The reinforcement detail specified in PennDOT DM4 and HSS tube were barely effective in controlling crack growing but spiral rebar effectively performed to delay crack growth as well as absorbing energy capacity. However, it was found that delaying cracking and strengthening the connection also caused the high lateral load in superstructures. Consequently, shape of HP pile were modified to introduce plastic hinge of the HP pile for reducing the lateral load in superstructures. Connections with modified HP pile significantly prevented crack propagations under the lateral displacement.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.24 no.4
• /
• pp.169-178
• /
• 2020

In a previous paper, ambient vibration tests were conducted on a cable stayed bridge with resilient-friction base isolation systems (R-FBI) to extract the dynamic characteristics of the bridge and compare the results with a seismic analysis model. In this paper, a nonlinear seismic analysis model was established for analysis of the bridge to compare the difference in seismic responses between nonlinear time history analysis and multi-mode spectral analysis methods in the seismic design phase of cable supported bridges. Through these studies, it was confirmed that the seismic design procedures of the "Korean Highway Bridge Design Code (Limit State Design) for Cable Supported Bridges" is not suitable for cable supported bridges installed with R-FBI. Therefore, to reflect the actual dynamic characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure is proposed that applies the seismic analysis method differently depending on the seismic isolation effect of the R-FBI for each seismic performance level.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.5
• /
• pp.112-119
• /
• 2015

In this paper, the strengthening method was proposed for improving the seismic performance of the vulnerable structural frames. To improve the brittle characteristics of columns, aramid fiber sheet was used for the lateral confinement of columns. And to introduce the energy dissipation capacity, a steel damper with S-shaped struts was installed. By making the unreinforced and reinforced specimens with full size specimens were evaluated for lateral load resistance capacity. It was confirmed the strengthening effects by the evaluation of failure shape, strength, stiffness degradation, and energy dissipation capacity. Also from the FE analysis using ABAQUS, the hysteretic behavior of the specimens were predicted and evaluated.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.5 no.4
• /
• pp.67-74
• /
• 2001

Structural engineers lately have an interest in the safety for equipments and facility in buildings subjected to earthquake. The stability of cultural assets was not considered for the earthquake induced vibration, while the integrity of structure has been considered through the resistant earthquake design. The purpose of this study aimed to analyze the behavior of isolation device named as \"Isolation table system\" and to evaluate its isolation performance through the experiment study. Isolation table is one of isolation systems to reduce the vibration which was transferred from slab to exhibition table. Experimental result shows that isolation table can reduce the vibration by 80-90% and its behavior is very stable within its maximal stroke.al stroke.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.6 no.2
• /
• pp.9-19
• /
• 2002

Steel piers and concrete-filled steel(CFS) piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as one of alternatives to RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. This paper, the first of two companion papers for the seismic performance of steel and CFS piers, tests steel and CFS piers under quasi-static cyclic loading to estimate their ductility and strength. Additional details such as rebars and base ribs are added to increase the ductility of a concrete-filled steel pier with minimum additional cost. Also, simplified numerical analyses using nonlinear spring and shell elements are examined for the estimation of the ductility and strength of concrete-filled steel piers and a steel pier. The result shows that concrete-filled steel peirs have higher energy absorption, i.e., ductility and strength than those of steel pier and increasing bonding between in-filled concrete and lower diaphragm, and the improved details of stress concentrated region would be important for the ductility and strength of a pier. Numerical results show that simplified modeling with nonlinear springs and shells has potential to be effective modeling technique to estimate the seismic performance of a concrete-filled steel pier.