• Title/Summary/Keyword: structural damage assessment

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Seismic Performance of Octagonal Flared RC Columns using Oblong Hoops (장방형 띠철근을 이용한 팔각형 플레어 RC 기둥의 내진성능)

  • Ko, Seong-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.1-9
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    • 2015
  • Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct. Details of reinforcement for rectangular section require a lot of rectangular hoops and cross-ties. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of the flared column. It can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency. The final objectives of this study are to suggest appropriate oblong hoop details and to provide quantitative reference data and tendency for seismic performance or damage assessment based on the drift levels such as residual deformation, elastic strain energy. This paper describes factors of seismic performance such as ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio and effective stiffness.

Displacement Ductility of Circular RC Column According to the Spacing of Spirals (나선철근 간격에 따른 원형 RC 기둥의 변위연성도)

  • Ko, Seong Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.71-82
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    • 2013
  • Eight small scale circular reinforced concrete columns (4.5 aspect ratio) were tested under cyclic lateral load with constant axial load. The selected test variables are longitudinal steel ratio (2.017%, 3.161%), transverse steel ratio, and axial load ratio (0, 0.07, 0.15). Volumetric ratio of spirals of all the columns is 0.335~0.894% in the plastic hinge region. It corresponds to 39.7~122.3% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The final objectives of this study are to provide quantitative reference data and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, steel fracture, etc. In this paper, describes mainly failure behavior, strength degradation behaviour, displacement ductility of circular reinforced concrete bridge columns with respect to test variables.

Propose of Capacity Spectrum Method by Nonlinear Earthquake Response Analysis (질점계 비선형 지진응답해석에 의한 구조물의 역량스펙트럼 제안)

  • You, Jin-Sun;Yang, Won-Jik;Yi, Waon-Ho;Kim, Hyoung-Joon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.6
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    • pp.501-508
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    • 2014
  • In this paper, a method on deducing the capacity spectrum based on nonlinear earthquake response analysis will be introduced. Damage assessment of general building draws the capacity spectrum through the Push-over analysis and the intersection point of capacity spectrum and demand spectrum is seen as performance point. Push-over analysis is the way to perform static analysis by using the equivalent static load changed from the effect of earthquake and predict the behavior of structures by earthquake. But, this method can not be taken into account in the effects of higher mode and the dynamic characteristic. Therefore, in order to calculate the capacity spectrum under dynamic properties of building. A capacity spectrum from going ahead with the nonlinear earthquake response analysis is suggested.

Assessment Level of Safe and Maintenance Based on Safety Inspection Data of Small Vulnerable Facilities in Domestic (국내 소규모취약시설 안전점검 데이터기반 안전 및 유지관리 수준 평가)

  • Kim, Min-Su;Lee, Jeong-Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.121-130
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    • 2021
  • Recently, the need for new approaches and recognition of safety and maintenance has been raised for small vulnerable facilities in Korea due to the acceleration of aging facilities, various safety accidents, and increased frequency of use. In particular, small vulnerable facilities(SVF), including most social welfare facilities, are facilities used by many of the vulnerable groups, and safety management is very important. Therefore, this study investigated various statuses based on safety inspection results (31,114 cases) conducted over the past 13 years (2008-2020) for small vulnerable facilities in Korea, and evaluated the characteristics of each field and safety and maintenance performance level. This aims to present policy directions for strengthening safety management of facilities for the vulnerable by using basic data such as improvement of safety standards and maintenance strategies for small vulnerable facilities in Korea in the future.

Dynamic Structural Response Characteristics of Stiffened Blast Wall under Explosion Loads (폭발 하중을 받는 보강된 방폭벽의 동적 구조 응답 특성에 관한 연구)

  • Kim, Sang Jin;Sohn, Jung Min;Lee, Jong Chan;Li, Chun Bao;Seong, Dong Jin;Paik, Jeom Kee
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.5
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    • pp.380-387
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    • 2014
  • Piper Alpha disaster drew attention to the damage likely to arise from explosions and fires on an offshore platform. And great concerns have been increased to prevent these hazards. Blast wall is one of the passive safety systems; it plays a key part of minimizing the consequences. However, a buckling due to explosion loads is a factor which can reduce the strength of blast wall. The buckling often occurs between web and flange at the center of blast wall. This study aims to find a solution for reinforcing its strength by installing a flat plate at the spot where the buckling occurs. First of all, ANSYS finite element method is adopted to numerically compute the structural resistance characteristic of blast wall by using a quasi-static approach. Sequentially, the impact response characteristics of blast wall are investigated the effect on thickness of flat plate by using ANSYS/LS-DYNA. Finally, pressure-impulse diagrams (P-I diagram) are presented to permit easy assessment of structural response characteristics of stiffened blast wall. In this study, effective use is made to increase structural intensity. of blast wall and acquired important insights have been documented.

Evaluation of Seismic Behavior for RC Moment Resisting Frame with Masonry Infill Walls (비내력벽을 가진 RC모멘트저항골조의 지진거동 평가)

  • Ko, Hyun;Kim, Hyun-Su;Park, Yong-Koo;Lee, Dong-Guen
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.5
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    • pp.13-22
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    • 2010
  • Masonry infill walls are frequently used as interior partitions and exterior walls in low- or middle- rise RC buildings. In the design and assessment of buildings, the infill walls are usually treated as non-structural elements and they are ignored in analytical models because they are assumed to be beneficial to the structural responses. Therefore, their influences on the structural response are ignored. In the case of buildings constructed in the USA in highly seismic regions, infill walls have a lower strength and stiffness than the boundary frames or they are separated from the boundary frames. Thus, the previously mentioned assumptions may be reasonable. However, these systems are not usually employed in most other countries. Therefore, the differences in the seismic behaviors of RC buildings with/without masonry infill walls, which are ignored in structural design, need to be investigated. In this study, structural analyses were performed for a masonry infilled low-rise RC moment-resisting frame. The infill walls were modeled as equivalent diagonal struts. The seismic behaviors of the RC moment-resisting frame with/without masonry infill walls were evaluated. From the analytical results, masonry infill walls can increase the global strength and stiffness of a structure. Consequently, the interstory drift ratio will decrease but seismic forces applied to the structure will increase more than the design seismic load because the natural period of the structure decreases. Partial damage of the infill walls by the floor causes vertical irregularity of the strength and stiffness.

Assessment of Fatigue Life of Out-Of-Plane Gusset Welded Joints using 3D Crack Propagation Analysis (3차원 피로균열 진전해석을 통한 면외거셋 용접이음의 피로수명 평가)

  • Jeong, Young-Soo;Kainuma, Shigenobu;Ahn, Jin-Hee;Lee, Wong-Hong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.129-136
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    • 2018
  • The estimation of the fatigue design life for large welded structures is usually performed using the liner cumulative damage method such as Palmgren-Miner rule or the equivalent damage method. When a fatigue crack is detected in a welded steel structure, the residual service life has to be estimated base on S-N curve method and liner elastic fracture mechanics. In this study, to examine the 3D fatigue crack behavior and estimate the fatigue life of out-of-plane gusset fillet welded joint, the fatigue tests were carried out on the model specimens. Investigations of three-dimensional fatigue crack propagation on gusset welded joint was used the finite element analysis of FEMAP with NX NASTRAN and FRANC3D. Fatigue crack growth analysis was carried out to demonstrate the effects of aspect ratio, initial crack length and stress ratio on out-of-plane gusset welded joints. In addition, the crack behaviors of fatigue tests were compared with those of the 3D crack propagation analysis in terms of changes in crack length and aspect ratio. From this analysis result, SIFs behaviors and crack propagation rate of gusset welded joint were shown to be similar fatigue test results and the fatigue life can also be predicted.

Assessment of Flood Flow Conveyance for Urban Stream Using XP-SWMM (XP-SWMM을 이용한 도시하천에서의 홍수소통능력 평가)

  • Hong, Jun-Bum;Kim, Byung-Sik;Seoh, Byung-Ha;Kim, Hung-Soo
    • Journal of Korea Water Resources Association
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    • v.39 no.2 s.163
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    • pp.139-150
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    • 2006
  • In recent, increasing of the impervious area gives rise to short concentration time and high peak discharge comparing with natural watershed and it is a cause of urban flood damage. Therefore, we have performed for structural and non-structural plans to reduce the damage from inundation. The Gulpo-cheon basin had been frequently inundated and damaged due to the water level of Han river. So, the Gulpo-cheon floodway was constructed with 20 meters width for flood control in the basin but it was not enough for our expectation and now we have a plan to expand the floodway to 80 meters. We use a XP-SWMM model developed based on EPA-SWMM version for analyzing the capacity of flood conveyance by the expansion of Gulpo-cheon floodway with the same 100 years return period design storm and the same tidal conditions of the Yellow sea. The flood conveyance after the expansion of floodway becomes three times comparing it with before the expansion. Also we simulate the flood discharge at the diversion point of Gulpo-cheon for the expanded condition of floodway and know that the discharge of about 300 m3/sec is flowing backward to the expanded floodway. Therefore we may need some kinds of hydraulic structures to prevent the back water.

Influence of Incidence Direction of Seismic Wave on the Probabilistic Seismic Fragility Assessment of Bridges (교량의 확률론적 지진취약도에 대한 지진파의 입사방향성의 영향)

  • Sina Kong;Yeeun Kim;Sinith Kung;Jiho Moon;Jong-Keol Song
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.37 no.3
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    • pp.151-162
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    • 2024
  • As the incidence direction of ground motion (or seismic wave) changes, the seismic response of the structure will also change according to that direction. In order to analyze the effect of the seismic response of the example bridge according to the direction of incidence of ground motion, the acceleration response spectra (Sa-T1) corresponding to the 1-second period obtained for various angles of incidence were obtained. Using Sa-T1, 40 sets of orthogonal pairs of horizontal component seismic waves corresponding to 5 types of percentiles were generated. Seismic vulnerability analysis of the bridge piers was performed by obtaining the seismic response of an example bridge according to the direction of incidence of ground motion. By analyzing the seismic vulnerability analysis of seismic waves corresponding to five types of percentiles, it was found that the median value of the seismic vulnerability curve differs by about 1.2 to 2.6 times depending on the incident direction of the seismic wave. In other words, depending on the incidence direction of seismic waves, the degree of damage to the bridge structure can vary by about 1.2 to 2.6 times.

Strength Prediction Equations for High Strength Concrete by Schmidt Hammer Test (슈미트 해머 시험에 의한 고강도 콘크리트의 강도 추정식)

  • Kwon, Young-Wung;Park, Song-Chul;Kim, Min-Su
    • Journal of the Korea Concrete Institute
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    • v.18 no.3 s.93
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    • pp.389-395
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    • 2006
  • For the assessment of exsiting concrete structures, it is important to get the real strength of concrete. The load test or core test has many problems due to cost time, easiness, structural damage, and reliability and so on. Thus, various non-destructive test and statistical analysis techniques for strength assessment have been developed. As a result the real strength of concrete can be obtained by both direct and indirect test. In this study, a series of experimental tests of core strength and Schmidt hammer tests on 3, 7, 14, 28, 90, 180, 365, and 730 days' were done for predicting the compressive strength of high strength concrete with 65.0MPa of 28-days' strength. Each experimental results was analyzed by simple regression analysis. Then, reliability level and error rate between the proposed equations and the existing ones was examined. However, the application of the exsisting equations was inadequate to high strength concrete, because they were conducted under normal strength concrete. Therefore, the following compressive strength equations were proposed for predicting the compressive strength of high strength concrete by Schmidt hammer test. The proposed equations by Schmidt hammer test are as follows.