• Title/Summary/Keyword: 내진보강방안

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Seismic Performance of Special Shear Wall with Modified Details in Boundary Element Depending on Axial Load Ratio (축력비에 따른 수정된 단부 횡보강상세를 갖는 특수전단벽의 내진성능)

  • Chun, Young-Soo;Park, Ji-Young
    • Land and Housing Review
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    • v.7 no.1
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    • pp.31-41
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    • 2016
  • In this paper, we propose experimental results, which target the major variables that influence the structural performance of a wall, as well as the resulting seismic and hysteretic behavior. Results also provide the basis for the application of performance based design by identifying the nonlinear hysteretic behavior of the wall with boundary element details recently proposed in previous study by Chun et al(2011). From the experimental results, the crack and fracture patterns of a specimen, which adopt the proposed boundary element details, showed similar tendencies regardless of whether axial force or high performance steel bars is applied. Furthermore, results show that the maximum strength of the specimen can be predicted accurately based on the design equation proposed by the standard. In addition, with a higher axial force, there is a tendency that both the initial load and maximum strength increase as deformation capacity reduces, requiring consideration of the reduced deformation capacity due to a high axial force. For walls under such high axial forces, using high performance steel bars is a very effective manner of enhancing deformation capacity. Therefore, reinforcing the plastic hinge region with boundary elements using high performance steel bars is preferable.

Seismic Performance of Special Reinforced Concrete Coupling Beams with Different Reinforcement Details (보강상세에 따른 특수전단벽 연결보의 내진성능)

  • Chun, Young-Soo;Park, Ji-Young
    • Land and Housing Review
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    • v.6 no.1
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    • pp.21-29
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    • 2015
  • Coupling beams posses proper strength, stiffness and ductility capacities to resist efficiently under seismic loads. The strength, stiffness and ductility capacities for special diagonally reinforced concrete coupling beam with a span-to-depth ratio 2.0 or less is higher than those of coupling beam with conventionally reinforced concrete coupling beam. However, diagonally reinforced detailing creates major construction problem. In this study, design alternatives for diagonally reinforced concrete coupling beams were experimentally investigated. The results show that angle reinforced coupling beam(specimen SA) exhibited a better stable behavior in comparison with non-diagonally coupling beams(specimens SB-series) and sustained corresponding drift ratio, peak-to-peak stiffness and cumulative dissipated energy in comparison to diagonally coupling beam(specimen CA).

A Study on the Seismic Performance Improvement of Mid and Low-Rise RC Grid Structures Using Steel Slab Hysteretic Damper (강재 슬래브 이력형 댐퍼(SSHD)를 이용한 중·저층 RC 격자 구조물의 내진성능 향상에 관한 연구)

  • Kim, Dong Baek;Lee, In Duk;Choi, Jung Ho
    • Journal of the Society of Disaster Information
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    • v.15 no.3
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    • pp.418-426
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    • 2019
  • Purpose: After analyzing the seismic capability of low-rise RC grid structures with insufficient seismic performance, the purpose of the project is to install steel slab hysteretic dampers (SSHD) to improve the seismic performance of beams and columns, and to suggest measures to minimize damage to the structure and human damage when an earthquake occurs. Method: The evaluation of the seismic performance of a structure is reviewed based on the assumption that the seismic performance is identified for the grid-type subway systems that are not designed to be seismic resistant and the installation of an SSHD system, a method that minimizes construction period, if insufficient, is required. Result: After the application and reinforce of structure with SSHD, and the results of eigenvalue analysis are as follows. The natural periodicity of longitudinal direction was 0.55s and that of vertical direction was 0.58s. Conclusion: As results of cyclic load test of structure with SSHD, the shear rigidity of damper is 101%, the energy dissipation rate is 108% and, plastic rotation angle of all column and beam is satisfied for $I_o$ level and therefore it is judged that the reinforce effect is sufficient.

Seismic Performance Evaluation of Staggered Wall Structures Using FEMA P695 (FEMA P695를 이용한 격간벽 구조의 내진성능평가)

  • Lee, Joon-Ho;Kang, Hyun-Goo;Lee, Min-Hee;Kim, Jin-Koo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.3
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    • pp.43-50
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    • 2012
  • The FEMA P695 document proposed a methodology to evaluate the collapse safety of a structure and the validity of the seismic design coefficients. In this study, the seismic performance of six- and twelve-story staggered wall structures with a middle corridor was evaluated based on the FEMA P695 procedure. The analysis results of the prototype structures were compared with those of the structures with an increased coupling beam depth or an increased re-bar ratio of the coupling beams in order to investigate the effect of retrofit. The adjusted collapse margin ratios (ACMR) of the model structures obtained from incremental dynamic analyses turned out to be larger than the specified limit states of an ACMR of 20%, which implies that the analysis model structures have enough strength against design level earthquakes. It was also observed that the increase in the re-bar ratio of the coupling beams between the staggered walls was more effective in increasing the ACMR than an increase in the depth of the coupling beams.

Proposed Seismic Performance Evaluation Enhancement for Existing School Building (기존 학교 건축물의 내진성능평가 및 보강방안 제안)

  • Hwang, Ji-Hoon;Jang, Jeong-Hyun;Yang, Kyeong-Seok;Choi, Jae-Hyouk
    • Journal of the Korean Institute of Educational Facilities
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    • v.19 no.4
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    • pp.29-38
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    • 2012
  • Recently large scale earthquake s are occurred around the world following the damage of buildings. So the interest of preparing for earthquake seismic design and seismic performance has becoming high. School buildings are though used for educational purpose; they are also used as emergency shelter for local residents during earthquake disaster. However, the current seismic design ratio of our country (Korea) is 3.7% and if massive earthquake is occurred it follows a serious damage. In order to overcome this situation, seismic performance evaluation is carried out for existing school building and an accurate and appropriate seismic retrofit is required based on performance evaluation to upgrade the existing school buildings. In this paper, nonlinear static analysis on existing school buildings for ATC-40 and FEMA-356 are carried out using the capacity spectrum method to evaluate seismic performance and to determine the need for retrofitting. In addition, after reinforcement to verify the effect of retrofit enhance the seismic performance is applied the seismic performance evaluation is carried out to verify the effect of seismic retrofit time history analysis using nonlinear dynamic analysis is also performed and nonlinear behavior of earthquake load of seismic retrofit of structures was also investigated.

A study on the improvement plan for precision safety diagnosis and seismic repair and reinforcement measures according to seismic performance evaluation (내진성능평가에 따른 정밀안전진단 및 내진 보수보강 조치의 개선방안 연구)

  • Kim, Jang-Ook
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.87-88
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    • 2022
  • For an earthquake-safe urban environment, the Republic of Korea conducts seismic performance evaluation in accordance with laws and guidelines to assign safety ratings and implement necessary management measures such as repairs and reinforcements. In the seismic performance evaluation result, structures lacking in preparation for earthquakes are prioritized and classified into measures such as repair, reinforcement, or careful observation to respond to physical risks such as earthquakes. Such repair and reinforcement work is not a one-time thing, but it is necessary to further enhance the effect through continuous follow-up observation. In this study, the location of the vertical and horizontal displacement measuring part of the construction part is displayed so that the post-construction status of the reinforcement construction part can be visually checked by identifying the problems in the process of post-monitoring in 2022 for the maintenance and reinforcement work of local governments' public facilities carried out in 2021. We propose a plan to institutionalize the installation of, inspection tools, and crack gauges at certain locations in the construction department, and to have facility managers periodically inspect and manage them with a smartphone program or the 'Facility Autonomous Safety Inspection' app.

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Evaluation of Shear Strength of Unreinforced Masonry Walls Retrofitted by Fiber Reinforced Polymer Sheet (FRP로 보강한 비보강 조적 벽체의 전단강도 산정)

  • Bae, Baek-Il;Yun, Hyo-Jin;Choi, Chang-Sik;Choi, Hyun-Ki
    • Journal of the Korea Concrete Institute
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    • v.24 no.3
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    • pp.305-313
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    • 2012
  • Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.

Quasi-Static Tests for Seismic Performance of Circular RC Bridge Piers (단일주 원형 철근콘크리트 교각의 내진거동에 관한 준정적 실험)

  • 정영수;이강균;한기훈;박종협
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.55-66
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    • 1999
  • Eight RC bridge plers have been made on a 1/3.4 scale model and have been tested in a quasi-static cyclic load so as to investigate their seismic performance. The ultimate objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete plers, which have been widely used for urban transportation facilities in Korea. Improtant test parameters are hoop ratio, axial load, load pattern, and etc. And noninear behaviors of test columns have been evaluated through their yield and ultimate strength, energy dissipation, ductility and load-deflection characteristics under quasi-static cyclic loads. From the quasi-static tests on 8 bridge piers, it is concluded that energy dissipation, ultimate strength and curvature for a given displacement factor ${\mu}={\Delta}/{\Delta}_y$ are higher for the seismically designed columns than for the nonseismically designed columns.

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Cyclic Seismic Testing of Steel Moment Connections Reinforced with Welded Straight Haunch (용접 수평헌치로 보강된 철골 모멘트 접합부의 반복재하 내진실험)

  • 이철호;권근배;정종현;오명호;구은숙
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.4
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    • pp.31-37
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    • 2002
  • Recently a simplified design procedure as well as load transfer model for seismic steel moment connections with welded straight haunch have been proposed by Lee and Uang. Cyclic seismic testing was conducted to verify the proposed design procedure and to develop the details that will prevent the cracking at the haunch tip, where stress concentration was the highest. All the specimens thus designed effectively pushed plastic hinging away from the haunch tip and were able to develop satisfactory plastic rotation capacity of 0.04 radian with no fracture. A sloped edge combined with drilling a hole near the haunch tip or a pair of stiffeners(partially or fully) extended from the beam web successfully prevented the crack initiation at the haunch tip. The strut action of the haunch web, which had been predicted from the previous analytical study, was also experimentally identified through the strain gage readings.

Deformation Capacity of Inverted V-Type Brace Strengthened by Built-up Non-welded Buckling Restraint Element (조립형 무용접 좌굴방지재로 보강된 역V형 가새의 변형성능)

  • Kim, Sun Hee;Moon, Ji Young;Choi, Sung Mo
    • Journal of Korean Society of Steel Construction
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    • v.27 no.3
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    • pp.261-271
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    • 2015
  • Steel concentrically braced frame is an efficient system that can acquire resistance against the lateral force of buildings with the least amount of quantity. In this study is intended to proceed on the research of schemes for reinforcement by supplementing previously installed H-formed brace with non-welded cold-formed plastic stiffening materials restricting the flexure and buckling and acquire a consistent strength on the tensile and compressive force. As for the measures of supplementing previously-installed inverted V-formed braced frame, stiffening materials in the previous studies were converted to weak-axial supplementing materials to suggest a specific scheme evaluating the structural function through an experiment of members, interpretation of members, and frame-focused experiment. Reinforced brace satisfied the requirement to be prevent AISC brace from being ruptured due to imbalanced strength in the beam.