Investigating Structural Stability and Constructability of Buildings Relative to the Lap Splice Position of Reinforcing Bars

Widjaja, Daniel Darma,Rachmawati, Titi Sari Nurul,권희훈,김선국 한국건축시공학회 2023 한국건축시공학회지 Vol.23 No.3

The design principles and implementation of rebar lap splice in architectural structures are governedby building regulations. Nevertheless, the minimization of rebar-cutting waste (RCW) is often impededby the mandatory requirements pertaining to the rebar lapping zone as prescribed in design codes. Inreal-world construction scenarios, compliance with these rules often falls short due to hurdlesconcerning productivity, quality, safety, time, and cost. This discrepancy between code stipulationsand on-the-ground construction practices necessitates an academic exploration. The goal of thisresearch was to delve into the effect of rebar lap splice placement on the robustness and constructabilityof building edifices. The study initially took on a review of the computation of rebar lappinglength and the rules revolving around the lapping zone. Following this, a structural robustness andconstructability examination was undertaken, focusing on adherence to the lap splice zone. Theinterpretations and deductions of the research led to the following insights: (1) the efficacy of rebar lapsplice is not solely contingent on the moment, and (2) the implementation of rebar lap splice beyondthe specified zone can match the structural integrity and robustness of those confined within thedesignated area. As a result, the constraints on the rebar lapping zone ought to be revisited andpossibly relaxed. The conclusions drawn from this research are anticipated to reconcile the disconnectbetween building codes and practical construction conditions, furnishing invaluable academicsubstantiation to further the endeavor of achieving near-zero RCW.

겹이음된 FRP 보강근으로 보강된 콘크리트 보의 휨거동

오홍섭 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 논문집 Vol.13 No.1

본 연구는 저자가 수행하고 있는 FRP로 보강된 콘크리트 보의 거동연구에 관한 일련의 연구 중 일부로서 본 연구에서는 인장보강근이 겹이음된 콘크리트보의 휨거동에 대한 실험적 연구결과를 제시하였다. 실험변수로는 보강근의 직경과 보강근의 겹이음길이를 적용되었으며, 총 14개의 겹이음된 실험체와 4개의 겹이음되지 않은 기준실험체에 대한 휨실험을 실시하여 각 실험변수인 보강근의 직경(10, 13, 16, 19mm)과 겹이음길이(0.72부터 1.58ld)에 대한 실험결과를 정리하였다. 각 보강근의 겹이음길이는 ACI 440에서 제시하고 있는 FRP 보강근에 대한 기준을 적용하였으며, 실험결과에서 사용된 FRP 보강근의 경우, 기준에서 제시하고 있는 부착길이에 대한 1.3과 1.6의 계수가 충분한 것으로 나타났다. This is a part of the extensive ongoing investigation being carried out by author to develop appropriate design procedure of the concrete member reinforced with FRP rebars instead of conventional steel rebars. This study presents the experimental results of a research programme to assess the structural characteristics of spliced rebar in reinforced concrete members with FRP reinforcement. The test variables are the diameter of FRP rebar and the embedment length. The development length (ld) was calculated according to the ACI 440 for FRP rebars in concrete. A total of 14 concrete beams reinforced with spliced FRP rebars and 4 reference beams reinforced with non-spliced FRP rebars were tested. The effects of bar size (10, 13, 16 and 19 mm) and splice length (from 0.72 to 1.58ld) on the bond strength were empirically evaluated. The test results indicate that a modification factor of 1.3 and 1.6 is relatively sufficient for the bond development length of glass FRP rebars in order to achieve an adequate tension lap splice length.

양방향 나사산 체결방식을 활용한 완전밀착형 커플러의 시공성 분석

박우열,홍성욱,양진국,고석화,안성훈 한국건축시공학회 2014 한국건축시공학회지 Vol.14 No.1

A tightened coupler with two way-threading is suggested to overcome the previous one-way threaded coupler. Theexperiment and a mock-up test were conducted to analyze the constructability of the suggested coupler. The aim of the mock-up test was to assemble the suggested coupler in horizontal rebar of mat footing and vertical rebar of semi-fabricated column bars. The method using the suggested coupler in semi-fabricated column bars is developed by analyzing the problem of fabricated column bars using the one-way threaded coupler. The result of the mock-up test showed that the time required to assemble the suggested coupler in the horizontal bars is shorter than it is for the one-way threaded coupler. In addition, the method using the suggested coupler in semi-fabricated column bars has advantages such as lower working loads, supporting safe work and strongly tightening the rebar. From these results, it is revealed that the suggested coupler is adequate to use in rebar work in terms of cost, quality and time. 본 연구에서는 기존의 일방향 나사산 커플러 이음을 개선한 양방향 나사산 체결방식을 활용한 완전밀착형 커플러를 제안하고 시공성을 분석하였다. 시공성을 분석하기위해 실물 실험 모형을 설치하여 실험하였다. 수평철근은매트기초의 수평철근을 대상으로 실험하였다. 수직철근의 경우 기존 선조립 커플러 이음 공법의 문제점을 분석하여 반조립 커플러 이음 공법을 제안한 후 적용하였다. 적용결과 수평철근의 경우 D25와 D29 모두 양방향 나사산 커플러 이음의 체결시간이 기존 커플러 이음보다 짧은것으로 나타났다. 수직철근은 반조립 형태로 배근할 경우기둥 주근 한 개를 약15초에 체결할 수 있는 것으로 나타났다. 기존 현장 조립 커플러 이음에 비해 쉽고 안전하게작업할 수 있고, 철근을 완전하게 밀착시킬 수 있기 때문에 품질 및 비용, 공기 측면에서 충분히 활용가능할 것으로 판단된다.

1축 인장시험을 통한 커플러가 철근 연성도에 미치는 영향 평가

우태련,이종한,정진환,정치영 한국구조물진단유지관리공학회 2018 한국구조물진단유지관리공학회 논문집 Vol.22 No.1

Recently, various reinforced concrete joints have been used in reinforced concrete structures. Therefore, it is important to grasp the tensile properties of the spliced rebar. In this study, uniaxial tensile tests were conducted on Grade 60 D22(#7), D29(#9), and two kinds of couplers manufactured according to ASTM A615 standard for evaluating ductility of coupler joints. The strain was measured using an image processing method more accurate and capable of measuring at various points freely. As the result of uniaxial tensile test, it was possible to calculate the stress-strain relationship and the longitudinal strain distribution according to the stress stages and it was founded that the average strain becomes lower as more occupying the coupler joint portions in the same gauge length. In addition, the empirical equations are proposed to account for the effect of the length of the coupler on the ultimate strain and the rupture strain. 최근 철근 콘크리트 구조물에 다양한 철근 이음이 사용되고 있다. 이에 따라 커플러 이음 철근의 인장 특성에 대한 파악이 중요해졌다. 본 연구에서는 커플러 이음 철근의 연성도에 대한 평가를 위하여 ASTM A615 기준에 따라 생산된 Grade 60 D22(#7), D29(#9), 그리고 두 종류의 커플러를 상대로 1축 인장시험을 수행하였다. 보다 정확하고 다양한 지점에서 자유로운 계측이 가능한 이미지 프로세싱 방법을 사용하여 변형률을 계측하였다. 1축 인장시험 결과, 응력-변형률 관계와 응력 단계별 종방향 변형률 분포를 산출할 수 있었고, 이를 통하여 동일한 표점거리 내에서 커플러 이음 부분이 많이 차지할수록 평균변형률이 낮아지는 것을 알 수 있었다. 또한 커플러 이음철근의 극한거동 및 파단 시 변형률에 대한 평가를 통해 커플러의 길이에 대한 한계상태변형률과 파단변형률과의 상관관계를 정식화하였다.

고강도 철근 사용에 따른 순수 철근량에 대한 정착 및 이음 철근량 비교

조승호,나승욱,노영숙 한국구조물진단유지관리공학회 2018 한국구조물진단유지관리공학회 논문집 Vol.22 No.1

Whilst it is common to construct high-rise buildings and long-span structures in the construction and building industry, there might be a number of problems such as excessive re-bars arrangement, deterioration of concrete quality, unnecessary quantity take-off and so forth. As these types of buildings and structures are getting more popular, it is widespread to apply high-strength materials such as high-strength concrete and re-bars to sustain durability and stability. This research aims to investigate the effectiveness of the high-strength reinforcing bars on the underground parking in a rigid-frame structure. In this study, the reinforcing bars with different yield strength were applied to corroborate the usefulness and practicability of the high-strength re-bars on the underground parking in a rigid-frame structure. The test results show that the quantity of reinforcement bars is lowered, as the yield strength of the re-bars are grown in general. However, the quantity of reinforcement bars on the development and splice has a tendency to increase slightly. Despite of the increase of the development and splice, the total quantity of reinforcing bars was reduced since the increasing ration of the pure quantity is higher than the development and splice. Base on the test results, it would be possible to achieve the reduction of reinforcing bars arrangement and lowering the amount of work to be done during a construction phase. Moreover, the reduced amount of bar arrangement will make it possible to improve workability and constructability of reinforced concrete structures. Ultimately, we will be able to attain improved quality and efficiency of construction using reinforced concrete. 초고층 및 장경간 등 대형 구조물에 대한 시공시 부재의 품질이 저하될 정도로 과다한 철근이 배근되고 있다는 문제점이 제기되고 있으며, 최근 건축되고 있는 초고층 건축물에서는 건물의 안정성과 내구성 등을 감안하여 사용 재료의 강도도 점차 증가하고 있다. 초고층 및 장경간 구조물의 시공에서 고강도 철근을 사용할 경우 기존의 일반 강도 철근에 비해 배근량 감소로 인하여 부재에서 배근 간격에도 여유를 줄 수 있어 시공성 향상, 공기단축, 접합부 상세가 간소화 되는 장점이 있다. 이 연구에서는 SD500, SD600 철근을 국내에서 설계되었거나 시공되어진 라멘 구조 형식의 지하주차장 건축물에 적용하여 각 부재별로 철근의 강도에 따른 순수 철근량에 대한 정착 및 이음 철근량 증감을 비교 분석한 결과 다음과 같은 결론을 얻었다. 계산된 철근의 정착 및 이음 물량은 사용철근의 강도가 증가함에 따른 정착 및 이음길이의 증가량과 순수 물량의 감소비율, 사용철근의 직경이 줄였을 때의 단면적 감소 등의 요인들에 의해 정착 및 이음 물량이 결정되었으며, 전체적으로 순수 물량에 대한 정착 및 이음 물량의 비율이 SD400대비 SD500의 경우는 증가하였지만 SD500대비 SD600의 경우는 감소하였다. 이는 보의 정착 및 이음 물량이 전체 정착 및 이음 물량에 미치는 영향이 크기 때문으로 판단된다. 한편 순수 물량에 대한 정착 및 이음 물량의 비율에서 SD400과 SD500의 차이와 SD400과 SD600의 차이가 미미하여 철근의 정착 및 이음 물량이 강도 증가에 따른 전체 철근 물량의 증감에는 큰 영향을 주지 않는 것으로 파악되었다.

노후도를 고려한 실크기 원형단면 교각의 내진성능 휨실험

이승건 ( Seung-geon Lee ),이수형 ( Soo-hyung Lee ),이혜린 ( Hyerin Lee ),홍기증 ( Kee-jeung Hong ) 한국구조물진단유지관리공학회 2021 한국구조물진단유지관리공학회 논문집 Vol.25 No.6

노후 교각은 내진설계가 적용되지 않아 소성힌지구역에 겹침이음이 대다수 존재한다. 철근부식은 철근 단면적 감소 및 겹침이음부의 거동저하를 유발하여 교각의 내진성능을 저하시킨다. 본 연구에서는 이러한 노후교각의 특성에 따라 철근부식, 겹침이음, 내진설계 및 내진보강 여부를 고려하여 실험체를 설계 및 제작하고 실험을 통해 그 영향을 조사하였다. 실험결과, 겹침이음 또는 철근부식은 변위연성도를 감소시킨다. 내진설계 상세 또는 강판 내진보강을 적용하면 충분한 변위연성도가 확보됨을 확인하였다. 모든 비내진실험체는 소성힌지구역 내의 횡철근 겹침이음부의 풀림으로 인해 주철근 좌굴과 심부콘크리트 압축파쇄가 발생하였다. 내진설계된 실험체는 철근부식에 의한 소성힌지구역 내 횡철근의 단면감소와 갈고리 풀림에 의해 주철근 좌굴 및 심부콘크리트 압축파쇄가 발생하였다. For old piers constructed when seismic design code had not been developed, lap splices usually exist in plastic hinge region. Corrosion of rebars causes decreasement in cross-sectional area of rebar and deterioration of lap-splice behaviour, thereby reducing the seismic performance of the old piers. In this research, according to these characteristics of old piers, test specimens are designed and manufactured considering rebar corrosion, lap splice, seismic design details, and seismic reinforcement. These effects are investigated through experiments. As a result of these experiment, rebar corrosion as well as lap splice reduces displacement ductility. When seismic design details or steel-plate reinforcement are applied, sufficient displacement ductility is expressed. For non-seismically designed specimens, loosening of the lap splice of transverse rebars caused buckling of longitudinal rebars and crushing of core concrete in plastic hinge region . For seismically designed specimen, area-reducing and untying of transverse rebars due to corrosion of rebars caused buckling of longitudinal rebars and crushing of core concrete.

슬리브형 철근 이음장치의 내력실험 및 성능평가

김호수(Kim Ho-Soo) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.8

The rebar splice equipments with sleeve connections are presented for the stable connection between the structural members in the remodelling and extension of reinforced concrete structure. To this end, the reasonable structural capacity evaluation should be performed for the practical use of this rebar splice equipments. Several types of rebar splice equipments are considered according to the sleeve connection shapes and field conditions. This study evaluates the structural capacity of rebar splice equipments through the bond stress experiment and analysis under the various design variables, and verifies the safety and efficiency of the rebar splice equipments with sleeve connections.

철근 커플러이음의 시공현황 및 개선방안에 관한 연구

김희주 ( Kim Hee-ju ),정서희 ( Jeong Seo-hee ),박민영 ( Park Min-young ),이영도 ( Lee Young-do ),김광희 ( Kim Gwang-hee ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.1

In order to achieve structural performance such as rebar clear spacing in the reinforced concrete structure construction, coupler splicing joints are becoming common. To confirm the performance of rebar splicing joints, quality verification is being carried out through coupler specimen tests. However, it can be said that the required performance is reached only when the actual construction in the field is constructed under the same conditions as the coupler splicing joint specimen. Therefore, the problems and solutions of the coupler splicing joint construction of the actual field was investigated in this study.

GFRP 보강근의 보강비에 따른 겹침이음 길이 산정에 관한 해석적 연구

최윤철,최창식,최현기 대한건축학회지회연합회 2012 대한건축학회연합논문집 Vol.14 No.3

Corrosion of the steel reinforcement in a cold and saline environments leads to the overall deterioration of reinforced concrete structures. Preventing such deterioration, Glass Fiber Reinforcement Polymer(GFRP) rebars are used in place of steel reinforcements. The lower bond stress of GFRP rebar which compared to steel rebar affects the development length and spliced length. In order to evaluate the lap spliced length of concrete beam reinforced with lap-spliced GFRP bar according to reinforcement ratio, nonlinear finite element analyses(FEM) are performed. And this paper is including the analytical result of FEM which taking the reinforcement ratio and lap splice length of GFRP rebar as a variable. In this study, 2D finite-element study was performed to evaluate the lap spliced length of GFRP rebar of concrete beam designed according to minimum requirements of the current design codes. ABAQUS was used for the FE analysis and verification was carried out through the previous researches. Total of 63 analytical models were analyzed in nonlinear Finite Element Method (FEM). From the analytical results, it was found that when reinforcement ratio is under the balanced reinforcement ratio, 1.7 times of steel rebar development length is required and 1.7 times development length should be used for over-reinforced beam. 본 연구는 겹침이음된 GFRP로 보강된 콘크리트 보의 적정 이음길이 평가를 위해 비선형 유한요소 해석을 수행하였다. 기존 연구자의 실험결과와의 비교를 통해 해석 모델을 검증하였으며, GFRP 보강근의 보강비에 따른 이음길이에 대한 변수해석을 수행하였다. 총 63개의 해석 변수를 통해 겹침이듬된 GFRP 보강근의 이음길이는 균형보강비 이하의 경우 1.7, 균형보강비 이상의 경우 1.6의 이음길이가 필요한 것으로 나타났다.

GFRP 보강근으로 겹침이음된 휨 부재의 휨성능

하상수(Ha Sang-Su) 대한건축학회 2011 大韓建築學會論文集 : 構造系 Vol.27 No.3

The objective of this study was investigated for the behavior of flexural member reinforcing glass fiber reinforced polymer(GFRP) bars with lap spliced at middle of the member. In this study, the specimens of 12 beams reinforced using GFRP bars were tested. In ten specimens, the GFRP bars were lap spliced at center. Test variables were lap spliced length, cover thickness, and ratio of reinforcing bar. The lap spliced length at center is 45db , 60db, and 75db. Cover thickness is 30㎜ and 50㎜. All beams were tested under 4-point loads so that the spliced length be subjected to a constant moment. No stirrups were used in the spliced region so that the tests result in conservative bond strengths. As a result of this test, the failure of all specimens with lap spliced results in concrete splitting. The flexural strengths of flexural member reinforcing GFRP bars with lap spliced at center were predicted through non-linear analyses of the cross-sections. The flexural capacities of members using GFRP bars can be determined through this study.