• Title/Summary/Keyword: 끼움벽

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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.

Influence of Strain-Hardening Cement Composite's Tensile Properties on the Seismic Performance of Infill Walls (변형경화형 시멘트 복합체의 인장성능에 따른 끼움벽의 내진성능)

  • Cha, Jun-Ho;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.24 no.1
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    • pp.3-14
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    • 2012
  • This paper describes experimental results on the seismic performance of SHCC (strain-hardening cement composite) infill wall for improving damage tolerance capacity of non-ductile frame. To investigate the effect of tensile strain capacity and cracking behavior of SHCC materials on the shear behavior of SHCC infill wall, three infill walls were fabricated and tested under cyclic loading. The test parameter in this study is a type of cement composites; concrete and SHCCs. The two types of SHCC materials were prepared for infill walls. In order to induce crack damages into the mid-span of the infill wall, each infill wall had two 100-mm-deep-notches on both sides. Test results indicated that SHCC infill walls showed superior crack control capacities and much larger drift ratios at the peak loads than RC (reinforced concrete) infill wall, as expected. In particular, due to the bridging actions of the reinforcing fibers, SHCC matrix used in this study would delay the stiffness degradation of infill wall after the first inclined cracking. Moreover, from the damage classes based on the cracks' maximum width in the infill walls, it was observed that PIW-SHD specimen possessed nearly threefold seismic capacities compared to PIW-SLD specimen. Also, from the results on the strain of diagonal reinforcements, it can be concluded that the SHCC matrix would resist a part of tensile stresses transferred along steel rebar in the infill wall.

Seismic Performance of Precast Infill Walls with Strain-Hardening Cementitious Composites (변형경화형 시멘트 복합체를 사용한 프리캐스트 끼움벽의 내진성능)

  • Kim, Sun-Woo;Yun, Hyun-Do;Jang, Gwang-Soo;Yun, Yeo-Jin
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.327-335
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    • 2009
  • In the seismic region, non-ductile structures often form soft story and exhibit brittle collapse. However, structure demolition and new structure construction strategies have serious problems, as construction waste, environmental pollution and popular complain. And these methods can be uneconomical. Therefore, to satisfy seismic performance, so many seismic retrofit methods have been investigated. There are some retrofit methods as infill walls, steel brace, continuous walls, buttress, wing walls, jacketing of column or beam. Among them, the infilled frames exhibit complex behavior as follows: flexible frames experiment large deflection and rotations at the joints, and infilled shear walls fail mainly in shear at relatively small displacements. Therefore, the combined action of the composite system differs significantly from that of the frame or wall alone. Purpose of research is evaluation on the seismic performance of infill walls, and improvement concept of this paper is use of SHCCs (strain-hardening cementitious composites) to absorb damage energy effectively. The experimental investigation consisted of cyclic loading tests on 1/3-scale models of infill walls. The experimental results, as expected, show that the multiple crack pattern, strength, and energy dissipation capacity are superior for SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

Seismic Performance of Concrete Masonry Unit (CMU) Infills in Reinforced Concrete Moment Framing System (철근콘크리트 모멘트 골조시스템에서 조적 끼움벽의 내진성능)

  • Hong, Jong-Kook
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.19-26
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    • 2019
  • The masonry infill walls are one of the most popular components that are used for dividing and arranging spaces in building construction. In spite of the fact that the masonry infills have many advantages, the system needs to be used with caution when the earthquake load is to be considered. The infills tend to develop diagonal compression struts during earthquake and increase the demand in surrounding RC frames. If there are openings in the infill walls, the loading path gets even complicated and the engineering judgements are required for designing the system. In this study, a masonry infill system was investigated through finite element analysis (FEA) and the results were compared with the current design standard, ASCE 41. It is noted that the equivalent width of the compression strut estimated by ASCE 41 could be 32% less than that using detailed FEA. The global load resisting capacity was also estimated by 28% less when ASCE 41 was used compare to the FEA case. Rather than using expensive FEA, the adapting ASCE 41 for the analysis and design of the masonry infills with openings would provide a good estimation by about 25% conservatively.

Effects of Fiber Volume Fraction and Cross-Section Shape Modifications on the Seismic Performance of Precast Infill Walls with SHCC (섬유의 혼입율 및 단면 형상 변화에 따른 SHCC 프리캐스트 끼움벽의 내진성능)

  • Kim, Sun-Woo;Lee, Young-Oh;Cha, Jun-Ho;Yang, Hae-Jun;Yun, Hyun-Do
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.125-126
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    • 2010
  • In this study is analysis of infill walls fiber volume fraction and reduced the inside cross-section of strain-hardening cement composite(SHCC) infill walls is to evaluate seismic performance experimentally.

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Effect of Reinforcement details on the Seismic Performance of Precast Strain-Hardening Cementitious Composite(SHCC) Infill Walls (보강상세에 따른 프리캐스트 변형경화형 시멘트 복합체 끼움벽의 내진성능)

  • Kim, Sun-Woo;Yun, Hyun-Do;Song, Seon-Hwa;Yun, Yeo-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.3 s.55
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    • pp.209-216
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    • 2009
  • Flexible frames on their own offer little resistance to lateral forces, resulting often in large deflections and rotations at the joints. On the other hand, walls subjected to lateral loads fail mainly in shear at relatively small displacements. Therefore, when the nonductile frames and wall act together, the combined action of the composite system differs significantly from that of the frame or wall alone. The objective of the study is to evaluate seismic response of infill walls with notched midsection. Reinforcement detail of wall was main variable in the experiment. Also SHCC was used in order to prevent damage concentration into notched midsection of walls. Test results, SHCC infill walls show the multiple crack patterns as expected. However, PIW-ND specimen exhibits less story drift, stiffness and energy dissipation capacity than those of PIW-NC specimen.

Inelastic Behavior of Reinforced Concrete Frame Structure with Shear Strength of Masonry Wall (조적벽의 전단강도를 고려한 철근콘크리트골조의 비탄성 거동)

  • Yoon, Tae-Ho;Kang, Kyung-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.9
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    • pp.4216-4222
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    • 2011
  • In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

Seismic Performance of Precast Infill Walls with Strain-Hardening Cement Composite (변형경화형 시멘트 복합체를 사용한 프리캐스트 끼움벽판의 내진성능)

  • Kim, Sun-Woo;Jeon, Esther;Kim, Yun-Su;Ji, Sang-Kyu;Jang, Gwang-Soo;Yun, Hyun-Do
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.89-92
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    • 2008
  • The seismic behavior of the lightly reinforced concrete frames (LRCFs) was controlled by the nonductile behavior of the critical regions. These critical regions require retrofit to improve the seismic behavior of the lightly reinforced concrete frames. Critical column end regions must be retrofit to increase the global ductility capacity. The objective of this research is to evaluate structural strengthening performance of lightly reinforced concrete frame with Strain hardening cement composite(SHCC) experimentally. The experimental investigation consisted of a cyclic load tests on 1/3-scale models of precast infill walls. Reinforcement detail of infill wall was variables in the experiment. The experimental results, as expected, show that the multiple crack pattern, strength, ductility and energy dissipation capacity are superior for specimen with SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.

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Experimental Study on RC Frame Structures with Non-Seismic Details Strengthened by Externally-Anchored Precast Wall-Panel Method (EPWM) (외부 앵커압착형 프리캐스트 벽체로 보강된 비내진 상세를 갖는 철근콘크리트 골조에 대한 실험적 연구)

  • Choi, Seung-Ho;Hwang, Jin-Ha;Lee, Deuck Hang;Kim, Kang Su;Kwon, Yong-Keun;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.451-458
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    • 2015
  • The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.

Seismic Retrofit of an Existing School Building using CIP-Infilled Shear Walls and Steel Braces (현장타설 끼움 전단벽 및 철골가새를 활용한 기존 학교 건물의 내진보강)

  • Youn, Gil-Ho;Kim, Sung-Ho;Kim, Yong-Cheol;Yun, Hyun-Do
    • Journal of the Korean Institute of Educational Facilities
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    • v.19 no.4
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    • pp.21-28
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    • 2012
  • This study proposes a procedure for evaluating the seismic performance and retrofit of a typical reinforced building (R/C) school buildings contructed in the 1980s. The procedure is derived from the Japanese Standard for Evaluation of Seismic Capacity of Existing Reinforced Concrete Buildings and Nonlinear Static Procedure (NSP) specified in Federal Emergency Management Agency (FEMA 356). In this study, the Japanese Standard was applied for evaluating the additionally required seismic performance in the existing school building. Cast-in-place (CIP) reinforced concrete infill walls and steel braces were used to seismically retrofit the existing school building located in the region of Hongsung in Chungnam. In the pushover analysis, i.e NSP, the hinge properties of columns, beams, infill walls and steel braces were carefully calibrated based on the existing experiment results in the available literatures. The predicted seismic performance for the retrofitted building was compared to that for the virgin building. Based on the seismic evaluation with the Japanese Standard and the FEMA 356 criteria, the addition of CIP reinforced concrete infill walls and steel braces have superior constructablility and can improve effectively the seismic performance of the existing school buildings constructed in 1980s.