인장력 측정용 턴버클의 극한강도 및 설계방법

이수헌,신경재,이희두,Lee, Swoo Heon,Shin, Kyung Jae,Lee, Hee Du 한국강구조학회 2013 韓國鋼構造學會 論文集 Vol.25 No.1

인장구조물의 하중을 지지하는 인장재 사이에서 한쪽은 왼나사, 다른 쪽은 오른나사로 구성되어 장력을 조절하는 장치가 턴버클이다. 인장재의 종류 및 연결 형태에 따라 다양한 종류가 존재하지만, 보편적으로 사용되는 기존의 턴버클은 장력을 측정할 수 없는 단점을 지니고 있다. 이에 장력조절의 기능과 함께 장력측정도 가능한 측정용 턴버클을 개발하였다. 본 논문에서는 기 개발된 측정용 턴버클의 비선형해석을 통한 극한강도와 측정 신뢰성을 확인하고자 한다. 기 개발된 100kN, 200kN, 300kN급 측정한계하중을 가지는 턴버클의 극한강도를 살펴보면, 측정한계하중의 5배 이상의 극한강도를 나타내었다. 추가로 300kN 이상의 고장력을 측정하기 위한 턴버클 개발을 위하여 검토한 결과 턴버클의 경사부가 휨과 인장에 저항하기 때문에 크기가 거대해지는 경향이 나타났다. 이에 300kN급 턴버클을 병렬연결하여 설치를 하면 600kN까지 측정할 수 있을 것이라는 발상에서 병렬연결장치를 구상하여 실험을 실시하였고, 그 가능성을 실험결과로부터 확인할 수 있었다. 또한 실험적인 인장구조물을 설치하여 개발된 턴버클이 외기에 노출되었을 시에 초기 하중의 변화 및 부식의 정도를 살펴보았다. A turn-buckle is capable of adjusting the tensile force by left-hand threads and right-hand threads between tension members. There are different types of turn-buckles according to tension member and connection form but the practical and existing turn-buckles are incapable of measuring the tensile force. A turn-buckle for adjusting and measuring tensile force has therefore been developed. This study shows the ultimate strength and reliability for measurement of the new turn-buckles through finite element analysis of the developed ones. From analytic results of the new turn-buckles which have the measurement limit loads of 100kN, 200kN and 300kN, the ultimate strength is approximately five times stronger than the measurement limit capacity. Additionally, a review of the new turn-buckle, which has the measurement limit load of over 300kN, shows that there is a tendency for the size of turn-buckle to become larger. So the connection devices were designed and the loading test was conducted from the concept that the parallel connection of turn-buckle with 300kN capacity can measure the tensile force of 600kN. The results of parallel loading test show the sufficient possibility. Furthermore, the mock-up test was constructed to investigate the release of initial load and corrosion when the new turn-buckle is installed at the outdoor and exposed to rain and atmosphere.

고강도 원형강관의 직각방향 거셋플레이트 접합부 실험 및 해석

이수헌,신경재,이희두,김우범,Lee, Swoo-Heon,Shin, Kyung-Jae,Lee, Hee-Du,Kim, Woo-Bum 한국강구조학회 2012 韓國鋼構造學會 論文集 Vol.24 No.2

원형강관의 접합부는 다양한 상세를 가지고 있으며 접합부가 항복에 이를 경우 복잡한 국부변형을 유발한다. 이러한 접합부의 국부변형을 고려한 단순화된 설계식의 제안은 매우 어려운 문제이다. 원형강관접합부 설계를 위한 현행 한국구조기준(KBC 2009)에서는 AISC의 설계식과 매우 유사한 단순화된 설계식을 제시하고 있다. 현행 설계식은 원형강관 부재의 재질에 대하여 항복강도는 최대 360MPa 항복비는 0.8로 각각 제한하고 있어서 구조기준에서 제한하는 최대항복강도 이상의 강재를 사용할 경우에는 유사 상세접합부를 대상으로 구조실험이나 합리적인 해석 등을 통하여 안전성을 검증한 후 사용하도록 하고 있다. 본 논문에서는 고강도강재(HSB600)와 일반구조용강재 (SS400)를 이용한 원형강관-직각방향 거셋플레이트 접합부에 횡력(수평력)이 작용하는 실험과 정밀모델 유한요소해석을 실시하였다. 유한요소해석 및 실험결과를 현행 설계식과 비교분석하여 향후 접합부 설계식의 개정에 기초적 자료로 사용될 수 있을 것이다. A connection composed of a circular hollow structural section (HSS) has complicated details, and exhibits a very complex local deformation when it reaches the yield stress. Given these circumstances, proposing a simple design equation considering local deformation is difficult. The design equations of the Korea Building Code (KBC 2009) for HSS joints are simple and are very similar to those of the AISC. These design equations limit the maximum yield stress up to 360MPa and yield ratio (yield strength/tensile strength) up to 0.8. This means that the material with yield strength exceeding 360MPa could be used after verification based on the test or rational analysis for the similar connection. This paper introduces an experimental program and finite element analysis (FEA) for the circular hollow section (CHS) with a transverse gusset plate made of high-strength steel (HSB600) or structural steel (SS400) when the joints are subjected to lateral force. Comparison of the design equations with the results of FEA and test may be used for the modification of the design equations.

고강도 원형강관의 길이방향 거셋플레이트 접합부 실험 및 해석

이수헌,신경재,이희두,김우범,Lee, Swoo-Heon,Shin, Kyung-Jae,Lee, Hee-Du,Kim, Woo-Bum 한국강구조학회 2012 韓國鋼構造學會 論文集 Vol.24 No.1

With the increase in the demand for high-rise buildings, the use of high-strength steel has likewise increased. Thus, it has become more necessary to study the resistance force of the high-strength hollow structural section (HSS) joint of 600MPa. Additionally, the current design equation in Korea limits maximum yield stress at 360MPa in the case of HSS. In other words, since the current specification does not apply to HSS of 600MPa, this study aims to investigate the applicability of design equations as well as examine the behavior of the connection through the experiment and finite element analysis (FEA) of the plate-tube connection of 600MPa. In particular, this paper presents the behavior of joints with the gusset plates welded in the longitudinal direction of the circular hollow section (CHS) when the joints are subjected to lateral force. Comparing design equations with the results of FEA and the test, existing design equations are underestimated to be 56~79% in the case of high-strength materials. 초고층 빌딩의 수요가 증가함에 따라 고강도 강관의 수요 또한 함께 증가하고 있다. 이에 고강도 고인성의 600MPa급 강관의 접합부 내력 연구가 필요하게 되었다. 또한 현행국내기준에는 강관의 경우 항복응력 360MPa 이하에 설계식을 적용하도록 되어 있다. 즉, 고강도강재를 이용한 600MPa 강관의 경우 현행기준을 적용할 수 없으므로 600MPa급 고강도 강관의 거셋플레이트 접합부의 내력실험 및 유한요소해석을 통하여 기존 설계식의 적용가능성을 조사하고 접합부의 거동을 연구하고자 한다. 특히, 본 논문에서는 원형강관에 길이 방향으로 거셋플레이트가 접합된 접합부에 횡력(수평력)이 작용하였을 때의 거동을 다루었다. 유한요소해석 및 실험결과를 설계식과 비교해보면, 고강도 강재에서는 기존의 설계식들이 56~79%로 과소평가되었다.

인장력 측정용 턴버클의 실험 및 해석

이수헌,신경재,Lee, Swoo Heon,Shin, Kyung Jae 한국강구조학회 2009 韓國鋼構造學會 論文集 Vol.21 No.2

서스펜션 구조시스템에서 구조물의 하중을 지지하는 인장재 사이에 삽입되어 인장력을 조절하는 장치가 턴버클이다. 하지만 기존의 상용화되어있는 턴버클은 인장재에 작용하는 하중의 크기를 측정하는 것이 어렵다. 그리하여 이러한 문제점을 해결하기 위하여 인장력 측정이 가능한 측정용 턴버클을 개발하고자 여러 연구를 진행해왔다. 본 논문에서는 이전 연구에서 문제점으로 언급된 국부적인 항복을 방지하고, 항복하중의 최대화에 초점을 두고 있으며 시험적인 단계를 넘어 실용화 단계의 새로운 측정용 턴버클을 제시하고자 한다. 이를 위하여, 이론적 해석을 바탕으로 제시된 해석모델로 유한요소 해석프로그램 ABAQUS 해석을 수행하고 제작된 실험체로 실험을 수행하였다. 그 결과 이론적 해석, ABAQUS 해석, 실험의 결과는 대체로 일치하는 것으로 나타났다. A turn-buckle inserted between tension members sustaining structural loads in the suspension structure system is a device capable of adjusting the tensile force. However, it is difficult to measure the tensile force that is applied to the tension member with the use of a conventional turn-buckle. So a measurable turn-buckle for tensile force measurement has been developed to improve on such a problem. This study focuses on the prevention of a local yielding as well as the maximization of yielding load mentioned in previous studies. A new type of turn-buckle for the measurement to practical use is suggested over the tentative purpose. For this purpose, the ABAQUS analysis of specimens based on theoretical analysis and tests are carried out. The differences among the results of the theoretical analysis, ABAQUS analysis, and the test were insignificant.

포스트텐션 콘크리트 보에서 비부착 외부강봉의 응력

이수헌,강현구,신경재,Lee, Swoo-Heon,Kang, Thomas H.K.,Shin, Kyung-Jae 한국공간구조학회 2015 한국공간구조학회지 Vol.15 No.1

This paper shows the simplified equation to predict the ultimate moment capacity and corresponding rod stress in reinforced concrete beam with external post-tensioning rods. Because the stress of external post-tensioning rod depends on the beam deflection, the previous analytical model for post-tensioned beams requires a tedious iteration process. Also, the stress equations in ACI code or other researchers' models are suitable only for internal tendons in concrete beams. In this study, given the lack of analytical approaches to predict the nominal stress of the external unbonded rod, a simple and robust equation has been proposed for externally post-tensioned concrete beams. It is concluded that the proposed equation predicted the stress of external steel rods in post-tensioned concrete beams reasonably well.

사전균열이 발생한 철근콘크리트 보의 외적 포스트텐셔닝 전단보강에서 보강깊이의 효과

이수헌(Lee, Swoo-Heon),신경재(Shin, Kyung-Jae),이희두(Lee, Hee-Du) 대한건축학회 2018 大韓建築學會論文集 : 構造系 Vol.34 No.11

This paper presents the shear strengthening effect of externally post-tensioning (EPT) method using high-strength steel rod in pre-cracked reinforced concrete (RC) beams. Three- and four-point bending tests were performed on a total of 8 specimens by adjusting the strengthening depths in the deviator position of EPT. The effective strengthening depths were 435, 535, and 610 mm. The pre-loading up to about 2/3 of ultimate load capacity measured in unstrengthened RC beam were applied in the beam to be post-tensioned. The EPT method was then applied to the pre-damaged RC beams and re-loading was added until the end of the test. EPT restored deflections of 3 mm or more, which account for about 40% of deflection when the pre-loading was applied. The shear strengthening increases more than 3 times and 36~107% in terms of the stiffness and load-carrying capacity compared to unstrengthening RC beams. The increased load-carrying capacities of the post-tensioned beam with strengthening depths of 435 and 535 mm are almost the same as 36~61%, and those of 610 mm are 84~107%, which shows the greatest shear strengthening effect.

인장력 측정용 턴버클의 거동해석

이수헌(Lee Swoo-Heon),신경재(Shin Kyung-Jae) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

Recently the study of heavy structure systems using a high strength tension member or cable has been increased abroad. The representative example is the suspension structure system. The tension member in the suspension structure systems used in long span structure resists load. A tum-buckle is a device adjusting the tensile force between tension members, but it is not easy- to measure the design tensile force by a conventional tum-buckle. So the measurable turn-buckle has been developed to improve the difficulty of measurement. The straight tensile elements of conventional turn-buckle were pre-deformed to a diamond shape, and, then, the lateral displacement of the curved elements was measured to convert it to load when tensile force was applied to the measurable tum-buckle. This study proposes analytical models of tum-buckles for the 100kN and 300kN capacities not being proposed in the previous study, and improves the shape of the previous tum-buckle for the 200kN capacity. The finite element analysis were conducted using eight-node reduced integration elements in ABAQUS/CAE. And the result of finite element analysis was compared with the result of theoretical analysis. The results of theoretical analysis agreed well with that of ABAQUS analysis. Therefore, the theoretical modeling could be used for the draft design of turn-buckle.

손상입은 철근콘크리트 보에서 데비에이터의 영향

이수헌 ( Lee Swoo-heon ),김보우 ( Kim Bo-woo ) 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.21 No.2

Externally post-tensioning steel rods led to a 25~66% increase of load-carrying shear capacity in damaged reinforced concrete beams when compared to a control beam. And the shear strength of a beam with two deviators was larger than that of a beam with one deviator. That shows how important a deviator location is for strengthening effect.

외적 포스트텐셔닝 강봉으로 보강된 철근콘크리트 보의 ABAQUS를 이용한 비선형해석

이수헌(Lee, Swoo-Heon),신경재(Shin, Kyung-Jae),김진욱(Kim, Jin-Wook),이희두(Lee, Hee-Du) 대한건축학회 2018 大韓建築學會論文集 : 構造系 Vol.34 No.2

Concrete is the well-used material in many architectural and civil structures. The behavior of concrete does exhibit a different characteristic in compression and tension, and it also shows an inelastic-nonlinear behavior. In addition, the concrete properties vary slightly depending on the environmental factor and manufacturer. These properties of concrete make the modeling or simulation of concrete material difficult. In reinforced concrete, particularly, there is a difficulty in bond-slip relationship between concrete and steel. However, in this paper, reserving remainder of these limits the finite element analysis for reinforced concrete beams through ABAQUS simulation has been carried out with some assumptions. Assumptions include the perfect bond of steel and concrete as well as the concrete damaged plasticity (CDP) in concrete property. There is a reasonable agreement between the experimental and numerical results, although the analytical strength and external rod deformation are slightly overestimated. The average and standard deviation between two results are 1.05 and 0.05, respectively. And the models and the computations lead to the evolution of fracture in bending beam.

손상입은 철근콘크리트 보의 외적 포스트텐셔닝에 의한 휨 보강

이수헌(Lee, Swoo-Heon),이희두(Lee, Hee-Du),이창수(Lee, Chang-Soo),신경재(Shin, Kyung-Jae) 대한건축학회 2017 大韓建築學會論文集 : 構造系 Vol.33 No.7

An experimental work was undertaken to observe and assess the behavior of damaged reinforced concrete (RC) beams with external post-tensioning steel rods. Six simply supported beams - two control beams and four comparable beams post-tensioned using externally steel rods - were tested in three-point bending. The main parameters are the diameter of external post-tensioning rods (ø22 mm and ø28 mm) and the ratio of tension steel reinforcement (p =0.0106 and 0.0166). For the post-tensioned beams, V-shaped profiles were used with a deviator located at the bottom of mid-span, and the post-tensioning force was applied to beams in order to overcome the low load-carrying capacity and existing deflection. The post-tensioning force acting on the steel rods was applied by tightening nuts of anchorage and its value was monitored by attached strain gauges. The initial strain of about 2000µε was chosen for post-tensioning force because it is about the maximum strain that two adult men can apply without struggle. Test results indicate that the externally post-tensioning increased the load-carrying capacity by about 40~101% and the flexural stiffness by about 27~43% compared to control beams. On the other hand, the larger steel reinforcements and external rods of the section disturbed the yielding of external rod at ultimate strength.