• Title/Summary/Keyword: 내진안정성

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Stability of Analytical Fragility Curve of Bridge on Elastic Modulus (탄성계수의 변화에 따른 교량의 해석적 손상도 곡선의 안정성)

  • Lee, Jong-Heon;Kang, Shin-Yeol;Kim, Tae-Hyeong;Lee, Soo-Choul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.175-182
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    • 2008
  • In performing a risk analysis of structure for earthquake, it is imperative to identify the vulnerability of structures associated with various stages of damage. And the earthquake resisting capability is needed for structures like bridge. So the damage analysis of bridges with or without isolator for earthquake effects is necessary. In this paper, the risk analysis of seismic isolated LRB bridges considering earthquake effects such as PGA, PGV, SA, SV, and SI is performed using fragility curves to assure the earthquake resisting capability of the structures. And, the stability of fragility curve is investigated with respect to elastic modulus.

An Experimental Study on the Structural Performance of Lightly Reinforced Concrete Frame Retrofitted with Concrete Block and Cast-In Place Infilled Wall (블록 끼움벽과 현장타설 끼움벽으로 보강된 비내진 상세 철근콘크리트 골조의 구조성능에 관한 실험적 연구)

  • Choi, Chang-Sik;Lee, Hye-Yeon;Kim, Sun-Woo;Yun, Hyun-Do
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.2
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    • pp.199-206
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    • 2005
  • In many other countries framed structures with inadequate lateral strength and stiffness have been strengthened by providing reinforced concrete infilled wall. There is a general agreement among researchers those infilled walls have 3-5times greater lateral strength compared with bare frame. The main objective of this research is to investigate the behavior and strength of reinforced concrete frames infilled with concrete block and cast-in-place reinforced concrete panels used for strengthening the structure against seismic action. For this purpose three 1/3 scale, one-bay, one-story reinforced concrete infilled frames were tested under reversed cyclic loading simulating the seismic effect. The results indicate that infilled walls increase both strength and stiffness significantly under lateral loads. Especially Strength capacity and initial stiffness of CIP infilled wall increased 3.8 times and 6.6 times higher than lightly reinforced concrete frame.

Seismic performance evaluation of Precast Concrete Lining (PCL) using the 1/5 scale down model test (1/5축소 모형실험에 의한 조립식 터널라이닝 (PCL)의 내진성능 평가)

  • Lee, Yong-Jun;Chung, Hyung-Sik;Lee, Doo-Hwa;Jo, Byung-Wan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.1
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    • pp.61-70
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    • 2004
  • Precast Concrete Lining (PCL) is invented in order to resolve the problem of the cast-in-place concrete lining in Norway, However PCL could not consider the effect of earthquake because an earthquake rarely occurs in the region of Northern Europe, Consequently, the analysis of the effect of earthquake on PCL should be made before introducing PCL to Korea. The purpose of this research is to evaluate the stability of tunnel applying PCL in the case of earthquake. To evaluate the seismic performance of PCL, we used shaking table apparatus by 1/5 scale down model. The result of this research is as shows that deep tunnells satisfied for Korea seismic design criteria.

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Seismic and Structure Analysis of a Temporary Rack Construction in a Nuclear Power Plant (원자력 발전소 공사용 임시받침대의 내진 및 구조해석)

  • Kim, Heung-Tae;Lee, Young-Shin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.10
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    • pp.1265-1271
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    • 2011
  • In this study, the safety of a rack structure was evaluated through seismic analysis considering fluid-structure interactions using a finite-element model. The rack structure was immersed under water, so it was influenced by the water. The fluid-structure interaction can be specified in terms of the hydrodynamic effect, which is defined as the added mass per unit length. Modal analysis and seismic analysis using the Floor Response Spectrum (FRS) were carried out under Operating Basis Earthquake (OBE) and Safe Shutdown Earthquake (SSE) conditions. The analytical maximum displacements of the rack structure were 0.29 and 0.36 mm under OBE and SSE conditions, respectively. The maximum stresses were 17.9 MPa under OBE conditions and 19.6 MPa under SSE conditions; these results corresponded to 23 % and 14% of the yield strength of the applied material, respectively.

Effect of Constrain Condition of Soil Nail Head on Slope Stability (쏘일 네일 두부 구속조건이 사면 안정성에 미치는 영향)

  • Kim, Yongeung;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.2
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    • pp.37-43
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    • 2014
  • Natural disasters such as earthquakes and tsunamis occur suddenly, so that they cause massive loss of lives and property. Especially earthquakes represent a particularly severe threat because of the extensive damage accompanied by them. In Korea, an earthquake-resistant design has been rarely applied to a design or construction of slope. However, in resent years, the researches for earthquake-resistance have been performed because the importance on the earthquake-resistance is perceived and highlighted. Soil nail method, one of the slope stability methods, is excellent for its constructability and cost effectiveness, as compared with other stability methods. Also, this method has been widely used for reinforced construction for slope stability. The studies of soil nail method have been performed on the interaction behavior between nails and slopes as well as the varied load condition such as static load, dynamic load and so on. Nevertheless, there has been minimal research regarding the constraint condition of nail head. In this study, the numerical analysis was performed for identifying effect on slope stability for the constrain condition of the soil nail. The result shows that the resistance of constrained the nail head on reinforced slope is larger compared to the one of unconstrained nail head.

Numerical Study on the Behavior of Ground and Structure in Geosynthetic-Reinforced Soil (GRS) Integral Bridges

  • Sim, Youngjong;Jin, Kyu-Nam;Hong, Eun-Soo;Kim, Hansung;Park, Jun Kyung
    • Land and Housing Review
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    • v.12 no.3
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    • pp.97-108
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    • 2021
  • In bridge abutment structures, lateral squeeze due to lateral stress of embankment placement and thermal movement of the bridge structure leads to failure of approach slabs, girders, and bridge bearings. Recently, GRS (Geosynthetic-Reinforced Soil) integral bridge has been proposed as a new countermeasure. The GRS integral bridge is a combining structure of a GRS retaining wall and an integral abutment bridge. In this study, numerical analyses which considered construction sequences and earthquake loading conditions are performed to compare the behaviors of conventional PSC (Pre-Stressed Concrete) girder bridge, traditional GRS integral bridge structure and GRS integral bridge with bracket structures (newly developed LH-type GRS integral bridge). The analysis results show that the GRS integral bridge with bracket structures is most stable compared with the others in an aspect of stress concentration and deformation on foundation ground including differential settlements between abutment and backfill. Furthermore, the GRS integral bridge with/without bracket structures was found to show the best performance in terms of seismic stability.

The Pseudo-Dynamic Test for the Seismic Retrofit System Utilizing Existing Bridge Bearings (교량의 기존 받침을 활용하는 내진보강시스템의 유사동적 실험)

  • Kwahk, Im-Jong;Cho, Chang-Beck;Kim, Young-Jin;Kwark, Jong-Won
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.1 s.53
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    • pp.21-27
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    • 2007
  • In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they Just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and lead rubber bearings far the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.

Seismic Performance Enhancement of Exposed Column-base Plate Weak-axis Connections for Small-Sized Steel Buildings (소규모 철골조건축물을 위한 약축방향 노출형 주각부의 내진성능 향상)

  • You, Young-Chan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.5
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    • pp.1-12
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    • 2019
  • The purpose of this study is to enhance the seismic performance of exposed column-base plate weak-axis connections for small-sized steel buildings. According to the site inspection for the small-sized building construction, the arbitrary connection details in steel buildings have been applied at the job site, which is considered to be insufficient to guarantee structural safety and stability considering the increased seismic risk in Korea. Therefore, a series of test programs had been done to develop enhanced connection details in order to ensue the adequate seismic stability and safety of small-sized steel buildings. From the test results, It was found that the exposed column-base plate weak-axis connections commonly used in Korea shows very poor seismic behavior due to the "Rocking" phenomena caused by the residual plastic deformation of anchor bolts between anchor plate and concrete. A series of hysteretic tests for finding that solution were conducted to reduce the "Rocking" phenomena of the column-base plate connections, and local buckling of webs in H-column. Finally the enhanced stable seismic behavior was obtained by reinforcing at least 8 anchor bolts with good bonding strength and stiffeners to the webs in H-column.

A Study on Seismic Performance Evaluation of Road Tunnel according to Seismic Analysis Conditions (내진해석 조건에 따른 도로터널 내진성능평가에 관한 연구)

  • Choi, Byoung-Il;Kim, Chan-Hee;Noh, Eun-Cheol;Ha, Myung-Ho;Park, Si-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.5
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    • pp.127-134
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    • 2021
  • When constructing a tunnel on a stable ground, stress is changed in the ground during excavation stage and installation of ground support materials. In the standards for safety evaluation of structures in use, it is suggested to perform numerical analysis reflecting the excavation stage. But method of seismic performance evaluation was not presented. Therefore, in this study, numerical analysis was performed with different analysis methods, and the results were compared and analyzed. As a result of the numerical analysis, seismic wave applied in the horizontal direction were no difference depending on the analysis methods. However, there was a big difference in the result according to the evaluation methods of tunnel member forces. When reviewing with the strength design method, the structure performance could be not satisfied depending on the existence or nonexistence of reinforcing bars. Based on these research results, it is suggested that the interpretation method should be clearly presented and reflected in the relevant standards.

Evaluation of the Seismic Stability of Fill Dam by Shaking Table Tests (진동대 시험을 통한 Fill Dam의 내진 안정성 평가)

  • Yoon, Won-Sub;Chae, Young-Su;Park, Myeon-Gu
    • Journal of the Korean Geosynthetics Society
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    • v.10 no.4
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    • pp.81-92
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    • 2011
  • In order to understand evaluation of the seismic stability of a fill dam, we made chambers of 1:100, 1:70, and 1:50 (the ratio of the miniature), considering the law of similarity based on drawings of three representative cross sections. And we measured an increase in acceleration, excess pore water pressure, and vertical/horizontal displacement after applying Hachinohe wave (long period), Ofunato wave (short period), and artificial wave, complying with the domestic standards, in order to evaluate the stability and interaction between the ground, the structure, and fluids based on the measurements. As a result, we could observe that displacement of the target cross section was relatively small compared to the allowed level of 30 cm, ensuring proper stability for an earthquake. Regarding the acceleration measurements, the increase rate was 20% for Hachinohe wave and Ofunato wave but 30% for the artificial wave. With respect to the excess pore water pressure, it was lower than 1 (which is the permissible ratio for liquefaction) ensuring proper stability as well.