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Estimation on clamping load of high strength bolts considering various environment conditions
나환선,최성모 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.4
Of high strength bolts, the torque shear type bolt is known to be clamped normally when pin-tails are broken. Sometimes the clamping loads on slip critical connections considerably fluctuate from the required tension due to variation of torque coefficient. This is why the viscosity of lubricant affects the torque coefficient by temperature. In this study, the clamping tests of high strength bolts were performed independently at laboratory conditions and at outdoor environment. The temperatures of outdoor environment candidates were ranged from -11°C to 34°C for six years. The temperature at laboratory condition was composed from -10°C to 50°C at each 10°C interval. At outdoor environment conditions, the clamping load of high strength bolt was varied from 159 to 210 kN and the torque value was varied from 405 to 556 Nm. The torque coefficients at outdoor environment were calculated from 0.126 to 0.158 when tensions were measured from 179 to 192 kN by using tension meter. The torque coefficients at outdoor environment conditions were analyzed as the range from 0.118 to 0.152. From these tests, the diverse equations of torque coefficient, tension dependent to temperature can be acquired by statistic regressive analysis. The variable of torque coefficient at laboratory conditions is 0.13% per each 1°C when it reaches 2.73% per each 1°C at outdoor environment conditions. When the results at laboratory conditions and at outdoor environment were combined to get the revised equations, the change in torque coefficient was modified as 0.2% per each 1°C and the increment of tension was adjusted as 1.89 % per each 1°C.
아라미드섬유 보강 강재 보 부재 휨성능에 관한 실험적 평가
나환선,이현주 한국복합신소재구조학회 2014 복합신소재구조학회 학술발표회 Vol.2014 No.04
The paper presents an experimental result to characterize the behaviour of steel beams reinforcement by pultruded reinforced polymer strips. Steel beam members reinforced with different thick AFRP on bottom flange plate were tested under one point bending configuration. Test results showed that the member force of one ply reinforced specimen was increased as 11% than control specimen when the two ply overlapped specimen was increased as 14% as usual.
복합재료 패널로 구성된 전단벽체의 반복거동 실험적 평가
나환선,이현주,김상봉,이도형 한국복합신소재구조학회 2018 복합신소재구조학회 학술발표회 Vol.2018 No.04
Structural insulated panels, structurally performed panels consisting of a plastic insulation bonded between two structural panel facings, are one of emerging products with a viewpoint of its energy and construction efficiencies. Of the SIPs, Cyclic test was conducted by two kinds of specimens: single panel and double panels. Cyclic test results, which were equivalent to static test results, showed that maximum load was 45.42kN, allowable shear load was 6.3kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. From performance of structural tests, the allowable shear load for panels was suggested to be at least 6.1kN/m.
고력볼트 미끄럼 접합부 도장표면의 크리프와 축력이완 상관관계
나환선,이현주 한국복합신소재구조학회 2011 복합신소재구조학회 학술발표회 Vol.2011 No.04
The initial clamping forces of the high strength bolts depending on the different faying surface conditions drop within 1,000 hours regardless of loading any other external force or loosening of the nut. This study focused on the mathematical model for relaxation confined to creep on coated faying surface after initial clamping. The quantitative equation for estimating long term relaxation was derived from nonlinear regression analysis for relation between the creep strain of coated surface and the elapsed time.
나환선,이현주,최성모,김우범 한국복합신소재구조학회 2015 복합신소재구조학회 학술발표회 Vol.2015 No.04
The clamping of torque shear high strength bolt is induced when the pin-tail is broken. Sometimes the clamping forces on slip critical connections do not meet the required tension due to torque coefficient dependent on conditions such as outdoor temperature, moisture and dust. From this study, the clamping forces of torque shear bolts at indoor conditions were compared with actual data investigated from 24 construction sites last five years. Similarly to foreign literature results, torque shear bolts showed that torque coefficients were fluctuated greatly by temperature conditions. The range of torque coefficient at indoor conditions was analyzed from 0.126 to 0.158 while tensions were indicated from 179 to 192 Nㆍm. Instead, the range of torque coefficient at site conditions was analyzed from 0.118 to 0.152. Based on this test, the variable trends of torque coefficient subjected temperature can be traced via statistic regressive analysis. In case of indoor conditions, it was showed that the variable of torque coefficient was 0.13% per 1℃, while the variable at actual site conditions reached 2.73% per 1℃.
나환선,박동수,김상봉 한국복합신소재구조학회 2018 복합신소재구조학회 학술발표회 Vol.2018 No.04
The purpose of this study is focused on evaluating the flexural behavior of concrete beam, which are arranged by mechanically spliced reinforcing bar. To compare the existent lapping method with newly registered splicing method, four cases of concrete beam are tested to be failed flexurally by monotonic loading. Based on test results, ductility of specimen mechanically all spliced by parallel threaded coupler is approximately 4 times greater than those of other specimens.
나환선,정훈 한국복합신소재구조학회 2016 복합신소재구조학회 학술발표회 Vol.2016 No.04
The clamping of torque shear high strength bolt is induced when the pin-tail is broken. However the tension forces induced shank of the bolt do not be known by now. This study focused to develop a quantitative method to identify the induced tension by analyzing the electric energy of which electric torque wrench was applied to high strength bolt at the break of pin tail. Based on this co-relation between tension and accumulated current, the regressive analysis was derived. The error rate between tension and accumulated current was 2.24%.
전동토크렌치를 이용한 고력볼트 축력 검사 기법 개발(2)
나환선,정훈 한국복합신소재구조학회 2016 복합신소재구조학회 학술발표회 Vol.2016 No.04
The clamping of torque shear high strength bolt is induced when the pin-tail is broken. However the tension forces induced shank of the bolt do not be known by now. This study focused to develop a quantitative method to identify the induced tension by analyzing the electric energy of which electric torque wrench (rpm 20) was applied to high strength bolt at the break of pin tail. Based on this co-relation between tension and accumulated current, the regressive analysis was derived. The error rate between tension and accumulated current was 5.06%.