• Title/Summary/Keyword: seismic performance

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Seismic Performance Assessment of Existing Circular Sectional RC Bridge Columns according to Lap-splice Length of Longitudinal Bars (축방향철근의 겹침이음길이에 따른 원형 RC교각의 내진성능평가)

  • Park, Kwang Soon;Seo, Hyeong Yeol;Kim, Tae-Hoon;Kim, Ick Hyun;Sun, Chang Ho
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.4
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    • pp.201-212
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    • 2014
  • The plastic hinge region of RC pier ensures its nonlinear behavior during strong earthquake events. It is assumed that the piers secure sufficient strength and ductility in order to prevent the collapse of the bridge during strong earthquake. However, the presence of a lap-splice of longitudinal bars in the plastic hinge region may lead to the occurrence of early bond failure in the lap-splice zone and result in significant loss of the seismic performance. The current regulations for seismic performance evaluation limit the ultimate strain and displacement ductility considering the eventual presence of lap-splice, but do not consider the lap-splice length. In this study, seismic performance test and analysis are performed according to the cross-sectional size and the lap-splice length in the case of longitudinal bars with lap-splice located in the plastic hinge region of existing RC bridge columns with circular cross-section. The seismic behavioral characteristics of the piers are also analyzed. Based upon the results, this paper presents a more reasonable seismic performance evaluation method considering the lap-splice length and the cross-sectional size of the column.

Study on Seismic Performance Evaluation and Verification of Seismic Safety for Power Cable Tunnels (개착식 전력구의 내진성능 평가 및 내진 안전성 검증)

  • Hwang, Kyeong-min;Chun, Nak-hyun;Chung, Gil-young;Park, Kyung-sung
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.4
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    • pp.439-445
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    • 2020
  • In this paper, the seismic performance evaluation was performed on 100 existing open-cut power cable tunnels, including ones that did not consider seismic design, in order to verify that the government's demand level (seismic special grade, 0.22 g). The results of the seismic performance evaluation show that most of the tunnels have seismic performance of 0.3 to 1 g, satisfying the level of the seismic special grade and securing the seismic safety. Meanwhile, the earthquake response analysis and structural test were performed to verify the validity of the method and the results of the seismic performance evaluation of the tunnels by the response displacement method, and to verify their seismic safety. As a result, the relative displacement due to the response displacement method under the 0.22 g earthquake was conservative than the results of the earthquake response analysis, and the results of load-displacement curves and response modification coefficient calculation by real scale structural tests showed the safety of the tunnels.

Seismic Performance Evaluation of Inverted V Braced Steel Frames with Considering P-Δ Effects: A Case Study (P-Δ 효과를 고려한 역 V형 철골 가새골조의 내진성능평가: 사례연구)

  • Lee, Cheol-Ho;Kim, Jeong-Jae
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.3
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    • pp.97-103
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    • 2004
  • Most of the columns in centrally braced steel frame buildings are usually designed as the gravity columns to reduce connection cost. For a rational seismic performance evaluation of centrally braced steel frame buildings, it is important to properly incorporate in the analysis  the P-${\Delta}$ effects arising from the gravity columns. An effective scheme for the P-${\Delta}$ effects modeling due to the gravity columns was illustrated based on the concept of fictitious leaning column. Seismic performance evaluation of inverted V braced steel frames with or without P-${\Delta}$ effects modeling was conducted by following the FEMA 273 NSP (Nonlinear Static Procedure). The problem in estimating dynamic P-${\Delta}$ modification factor (C3) in FEMA 273 was discussed. The results of this study indicated that the P-${\Delta}$ effects should be included in the seismic performance evaluation of centrally braced steel frames. This study also showed that the inverted V braced frames, retrofitted by applying the tie bars to redistribute the inelastic demand over the height of the building, exhibit significantly improved seismic performance.

Development of a Precast Concrete Structural Wall Adopting Improved Connections in the Plastic Hinge Region (소성힌지 영역의 접합부를 개선한 PC 구조벽체의 개발)

  • Kang, Su-Min;Oh, Jae-Keun;Kim, Ook-Jong;Lee, Do-Bum;Park, Hong-Gun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.2
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    • pp.15-26
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    • 2010
  • The purpose of this study is to develop a precast concrete structural wall system that can assure reliable seismic performance. In previous studies, the connections of precast concrete structural walls have had some problems in their seismic performance. Therefore, this research proposes precast concrete structural walls which have an improved seismic performance. One is a hybrid precast concrete structural wall that is composed of a reinforced concrete component and a precast concrete component, and another is a precast concrete wall whose reinforcements have a partially reduced section and are partially unbonded from the surrounding concrete. To evaluate the seismic performance of the proposed precast concrete structural walls, the behavior of three specimens, including a reinforced concrete wall, were subjected to reversed cyclic combined flexure and shear. According to the test results, the proposed precast concrete structural walls have reliable seismic performance.

Experimental study on seismic behavior of reinforced concrete column retrofitted with prestressed steel strips

  • Zhang, Bo;Yang, Yong;Wei, Yuan-feng;Liu, Ru-yue;Ding, Chu;Zhang, Ke-qiang
    • Structural Engineering and Mechanics
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    • v.55 no.6
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    • pp.1139-1155
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    • 2015
  • In this study, a new retrofitting method for improving the seismic performance of reinforced concrete column was presented, in which prestressed steel strips were utilized as retrofitting stuff to confine the reinforced concrete column transversely. In order to figure out the seismic performance of concrete column specimen retrofitted by such prestressed steel strips methods, a series of quasi-static tests of five retrofitted specimens and two unconfined column specimen which acted as control specimens were conducted. Based on the test results, the seismic performance including the failure modes, hysteresis performance, ductility performance, energy dissipation and stiffness degradation of all these specimens were fully investigated and analyzed. And furthermore the influences of some key parameters such as the axial force ratios, shear span ratios and steel strips spacing on seismic performance of those retrofitted reinforced concrete column specimens were also studied. It was shown that the prestressed steel strips provided large transverse confining effect on reinforced concrete column specimens, which resulted in improving the shearing bearing capacity, ductility performance, deformation capacity and energy dissipation performance of retrofitted specimens effectively. In comparison to the specimen which was retrofitted by the carbon fiber reinforced plastics (CFRP) strips method, the seismic performance of the specimens retrofitted by the prestressed steel strips was a bit better, and with much less cost both in material and labor. From this research results, it can be concluded that this new retrofitting method is really useful and has significant advantages both in saving money and time over some other retrofitting methods.

Shaking Table Test for Seismic Performance Evaluation of Non-Seismic Designed Wall-Type Apartment (내진설계 되지 않은 공동주택의 진동대 실험에 의한 내진성능 평가)

  • Chung, Lan;Lee, Joung-Woo;Park, Tae-Won
    • Journal of the Korea Concrete Institute
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    • v.18 no.6 s.96
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    • pp.721-728
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    • 2006
  • Earthquakes are reported thai building structures have been colossal damaged, but before 1988 designed structures which were not applicate seismic design code have no seismic performance. Especially, for the apartment structures were indicated that it have no resist wall element of earthquake before 1988 designed structures. We have to evaluate for seismic performance this structures, therefore it will be retrofitted for seismic index sufficient structures. We performed seismic performance evaluation for model structures by MIDAS which is general structure analysis software. In this study, it was performed shaking table test to evaluate model structure which is reinforcement concrete and 5 floors for seismic performance index. We made specimens by similar's law and tested shaking table test. In the shaking table test it is not performed prototype model test because of space and equipment condition. So we had made scale-down model for 1/5 by similar's law. That's why it needs for the evaluation of performance. However, it is not possible to do an experiment of prototype owing to the shortage of space and the limit of an experimental instrument in the shaking table test. Then, modeling and reducing the part of prototype do the experiment. In this experiment a shaking table test is done and seismic performance of model structures is evaluated by using similitude laws for scale down specimen. As a result it is proved that non-seismic design structures need to retrofit since seismic performance shows life safe grade in 0.12g of an earthquake.

A Propose on Seismic Performance Evaluation Model of Slope using Artificial Neural Network Technique (인공신경망 기법을 이용한 사면의 내진성능평가 모델 제안)

  • Kwag, Shinyoung;Hahm, Daegi
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.2
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    • pp.93-101
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    • 2019
  • The objective of this study is to develop a model which can predict the seismic performance of the slope relatively accurately and efficiently by using artificial neural network(ANN) technique. The quantification of such the seismic performance of the slope is not easy task due to the randomness and the uncertainty of the earthquake input and slope model. Under these circumstances, probabilistic seismic fragility analyses of slope have been carried out by several researchers, and a closed-form equation for slope seismic performance was proposed through a multiple linear regression analysis. However, a traditional statistical linear regression analysis has shown a limit that cannot accurately represent the nonlinearistic relationship between the slope of various conditions and seismic performance. In order to overcome these problems, in this study, we attempted to apply the ANN to generate prediction models of the seismic performance of the slope. The validity of the derived model was verified by comparing this with the conventional multi-linear and multi-nonlinear regression models. As a result, the models obtained through the ANN basically showed excellent performance in predicting the seismic performance of the slope, compared to the models obtained by the statistical regression analyses of the previous study.

Study for Dynamic Response of EDF System (EDF 시스템의 동적거동 특성에 관한 연구)

  • 한규승;박선규;김남식
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.399-402
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    • 1999
  • This study is about seismic performance of the EDF(Electricite De France) system, that is among various base isolator. We get solutions of equation of motion of this system for displacement, velocity, acceleration and compared with solutions using finite element program. And, through shaking table tests we will prove seismic performance

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Seismic Performance Assessment of Unreinforced Masonry Wall Buildings Using Incremental Dynamic Analysis (증분동적해석을 통한 비보강 조적벽식 건물의 내진성능 평가)

  • Kwon, Ki Hyuk;Kim, Man Hoe;Kim, Hyung Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.28-39
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    • 2013
  • The most common housing type in Korea is low-rise buildings with unreinforced masonry walls (UMWs) that have been known as a vulnerable seismic-force-resisting system (SFRS) due to the lack of ductility capacities compared to high lateral stiffness of an UMW. However, there are still a little experimental investigation on the shear strength and stiffness of UMWs and on the seismic performance of buildings using UMWs as a SFRS. In Korea, the shear strength and stiffness of UMWs have been evaluated with the equations suggested in FEMA 356 which can not reflect the structural and material characteristics, and workmanship of domestic UMW construction. First of all, this study demonstrates the differences in shear strength and stiffness of UMWs obtained from between FEMA 356 and test results. The influence of these differences on the seismic performance of UMW buildings is then discussed with incremental dynamic analyses results of a prototype UMW building that were selected by the site survey of more than 200 UMW buildings and existing test results of UMWs. The seismic performance assessment of the prototype UMW building are analyzed based on collapse margin ratios and beta values repesenting uncertainty of seismic capacity. Analysis results show that the seismic performance of the UMW building estimated using the equations in FEMA 356 underestimates both a collapse margin ratio and a beta value compared to that estimated by test results. Whatever the estimation is carried out two cases, the seismic performance of the prototype building does not meet the criteria prescribed in a current Korean seismic code and about 90% collapse probability presents for more than 30-year-old UMW buildings under earthquakes with 2400 return years.

Economic Analysis of a 5-Story RC OMRF Retrofitted with Modified Epoxy Mortar for Improving Seismic Performance (변성에폭시 모르터로 내진보강한 5층 철근콘크리트 보통모멘트골조의 경제성 분석)

  • Kang, Suk-Bong;Kwak, Jongman;Shin, Dongwoo;Son, Kiyoung
    • Journal of the Korea Institute of Building Construction
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    • v.14 no.3
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    • pp.207-215
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    • 2014
  • As a reinforcement material for RC members, the modified epoxy mortar has been reported one of the superior materials since the material can improve the load capacity and the seismic performance of the RC members. However, there were few experimental studies and analytical research for improving seismic performance with the material. This study is to propose an effective reinforcement plan for RC Ordinary Moment Resisting Frame (OMRF) with the evaluation of seismic performance and economic analysis. For the objective, first, the load-deflection curve of a simple beam specimen was compared with the analytical results. Second, a 5-story RC OMRF structure was designed only for gravity load and the alternatives for seismic reinforcement were suggested. Third, pushover analysis was executed for evaluation of design coefficients and seismic performance of the structures. Finally, an effective reinforcement plan was suggested based on the results of quantity take-off and economic analysis. The findings of this study can be utilized as the basic data when the modified epoxy mortar is applied to practice for improving the seismic performance of RC members.