• 한국구조물진단유지관리공학회 논문집
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• 제13권3호통권55호
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• pp.217-224
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• 2009

지진으로부터 구조물의 안전을 확보하기 위하여 많은 공학자들의 연구가 계속되고 있다. 본 연구에서는 납의 이력특성을 이용하여 지진하중을 감소시키는 LRB(lead rubber bearing)의 감쇠능력에 대한 실험적 연구를 수행하였다. 납 플러그의 면적비를 주요변수로 설계한 2종류 12개의 시험체를 제작하여 변위제어시험을 시행하였다. 감쇠비 결정을 위한 이력감쇠곡선을 얻기 위하여 2개의 시험체가 한 쌍을 이루도록 배치하고 3회 반복이력시험을 수행하였다. 실험결과로부터 본 연구에서의 납 플러그 면적비가 큰 LRB는 지진시 구조물의 지진하중을 감소시키는데 충분한 감쇠비를 보유하고 있음을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.617-628
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• 2017

In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

• 전산구조공학
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• 제8권4호
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• pp.159-171
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• 1995

한 cycle의 이력곡선 loop을 완전히 표현하기 위해서는 pinch force, drift offset, effective stiffness, unloading, reloading, tangential stiffness 등의 변수가 필요하게 된다. 각 이력 loop에 대해 이들 변수들은 에너지 소산정도에 따라 변위와 축력의 함수로 표현될 수 있다. 본 논문에서는 먼저 16개의 전단벽 실험에서 얻어진 이력곡선 데이타를 분석하여 앞에 기술된 모든 변수를 표준화된 변위(.DELTA/.DELTA.y)의 함수로 표현했으며 이를 바탕으로 이력곡선의 포락선으로 표현되는 힘-변위관계를 예측할 수 있는 6개의 step을 제시하였다. 제시된 기법으로 구해진 비탄성 힘-변위관계는 실험곡선과 비교되었으며 내진설계에 있어서 가장 중요한 요소중 하나인 구조물의 비탄성 힘-변위관계를 예측하는 편리한 기법으로 이용될 수 있음을 보였다.

• Advances in concrete construction
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• 제8권3호
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• pp.173-185
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• 2019

This article presents a comparative study of the effect of steel layouts on the seismic behavior of transition steel-concrete composite connections, both experimental and analytical investigations of concrete filled steel tube-reinforced concrete (CFST-RC) and steel reinforecd concrete-reinforced concrete (SRC-RC) structures were conducted. The steel-concrete composite connections were subjected to combined constant axial load and lateral cyclic displacements. Tests were carried out on four full-scale connections extracted from a real project engineering with different levels of axial force. The effect of steel layouts on the mechanical behavior of the transition connections was evaluated by failure modes, hysteretic behavior, backbone curves, displacement ductility, energy dissipation capacity and stiffness degradation. Test results showed that different steel layouts led to significantly different failure modes. For CFST-RC transition specimens, the circular cracks of the concrete at the RC column base was followed by steel yielding at the bottom of the CFST column. While uncoordinated deformation could be observed between SRC and RC columns in SRC-RC transition specimens, the crushing and peeling damage of unconfined concrete at the SRC column base was more serious. The existences of I-shape steel and steel tube avoided the pinching phenomenon on the hysteresis curve, which was different from the hysteresis curve of the general reinforced concrete column. The hysteresis loops were spindle-shaped, indicating excellent seismic performance for these transition composite connections. The average values of equivalent viscous damping coefficients of the four specimens are 0.123, 0.186 and 0.304 corresponding to the yielding point, peak point and ultimate point, respectively. Those values demonstrate that the transition steel-concrete composite connections have great energy dissipating capacity. Based on the experimental research, a high-fidelity ABAQUS model was established to further study the influence of concrete strength, steel grade and longitudinal reinforcement ratio on the mechanical behavior of transition composite connections.

• Computers and Concrete
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• 제17권2호
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• pp.227-240
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• 2016

An analytical study was conducted to investigate the effect of the shape and spacing of modified inclined studs used as shear connector between concrete and steel plate on the cyclic behavior of steel plate concrete (SC) shear wall. 9 different analysis cases were adopted to determine the optimized shape and spacing of stud. As the results, the skeleton curves were obtained from the load-displacement hysteresis curves, and the ultimate and yielding strengths were increased as the spacing of studs decrease. In addition, the strength of inclined studs is shown to be bigger compared to that of conventional studs. The damping ratios increased as the decrease of stiffness ratio. Finally, with decreasing the spacing distance of studs, the cumulative dissipated energy was increased and the seismic performance was improved.

• 한국재료학회지
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• 제2권5호
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• pp.313-319
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• 1992

The mechanisms of fatigue crack growth (FCG) in a Ti$_3$Al-based (${\alpha}_2$) alloy, Ti-24Al-11Nb (a/o) with acicular microstructure were studied with particular attention focused on the fatigue crack path through the microstructure and on the effects of specimen orientation and crack closure. The results showed that the fatigue cracks of Ti-24Al-11Nb alloy grew much faster than conventional titanium alloys, with little difference in FCG rates for TL and TS orientations. The fatigue crack paths revealed crystallographic transgranular fracture with frequent serrations and branching. This is in agreement with the known effects of slip planarity and microstructure on the FCG behavior. The load-displacement hysteresis loops showed that the crack closure influenced the FCG behavior.

• Steel and Composite Structures
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• 제17권3호
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• pp.287-303
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• 2014

8 steel reinforced concrete (SRC) columns with the encased steel ratio of 13.12% and 15.04% respectively were tested under the test axial load ratio of 0.33-0.80 and the low-frequency cyclic lateral loading. The cross sectional area of composite columns was $500mm{\times}500mm$. The mechanical properties, failure modes and deformabilities were studied. All the specimens produced flexure failure subject to combined axial force, bending moment and shear. Force-displacement hysteretic curves, strain curves of encased steels and rebars were obtained. The interaction behavior of encased steel and concrete were verified. The hysteretic curves of columns were plump in shapes. Hysteresis loops were almost coincident under the same levels of lateral loading, and bearing capacities did not change much, which indicated that the columns had good energy-dissipation performance and seismic capacity. Based on the equilibrium equation, the suggested practical calculation method could accurately predict the flexural strength of SRC columns with cross-shaped section encased steel. The obtained M-N curves of SRC columns can be used as references for further studies.

• 한국지진공학회논문집
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• 제8권4호
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• pp.1-10
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• 2004

반복 횡하중을 받는 콘트리트 충진 탄소섬유 튜브 기둥의 휨거동을 분석하기 위하여 실험을 수행하였다. 콘크리트 충진 각형 탄소섬유 튜부 기둥의 휨거동에 영향을 미치는 탄소섬유의 와인딩 각도와 두께를 변수로 선택하여 거동을 평가하였다. 콘트리트 충진 탄소섬유 튜브 기둥의 휨거동 보다 정확하게 분석하기 위하여 설정된 두 변수를 동시에 고려하였다. 실험의 결과에서 얻어진 하중-변형 곡선을 이용하여 콘크리트 충진 각형 탄소섬유 튜브 기둥이 휨강도, 변형능력 및 에너지 소산능력을 조사하였다. 또한 기존 구조물과의 비교를 위하여 철근콘크리트 조적벽과 콘크리트를 충진한 각형 탄소섬유 튜브 기둥과의 연성 능력을 비교 평가하였다.

• Earthquakes and Structures
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• 제22권5호
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• pp.461-473
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• 2022

Energy-saving block and invisible multiribbed frame composite wall (EBIMFCW) is an important shear wall, which is composed of energy-saving blocks, steel bars and concrete. This paper conducted seismic performance tests on six 1/2-scale EBIMFCW specimens, analyzed their failure process under horizontal reciprocating load, and studied the effect of axial compression ratio on the wall's hysteresis curve and skeleton curve, ductility, energy dissipation capacity, stiffness degradation, bearing capacity degradation. A formula for calculating the peak bearing capacity of such walls was proposed. Results showed that the EBIMFCW had experienced a long time deformation from cracking to failure and exhibited signs of failure. The three seismic fortification lines of the energy-saving block, internal multiribbed frame, and outer multiribbed frame sequentially played important roles. With the increase in axial compression ratio, the peak bearing capacity and ductility of the wall increased, whereas the initial stiffness decreased. The change in axial compression ratio had a small effect on the energy dissipation capacity of the wall. In the early stage of loading, the influence of axial compression ratio on wall stiffness and strength degradation was unremarkable. In the later stage of loading, the stiffness and strength degradation of walls with high axial compression ratio were low. The displacement ductility coefficients of the wall under vertical pressure were more than 3.0 indicating that this wall type has good deformation ability. The limit values of elastic displacement angle under weak earthquake and elastic-plastic displacement angle under strong earthquake of the EBIMFCW were1/800 and 1/80, respectively.

• 대한토목학회논문집
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• 제35권1호
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• pp.229-236
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• 2015

본 연구는 에폭시 아스팔트 포장 내부 상태 평가를 위해 이동 차량하중 모사가 가능한 회복탄성계수 실험과 LWD 실험을 수행하였다. 회복탄성계수 실험에서 측정된 변위는 일반 아스팔트와 달리 잔류변형이 매우 미소한 수준으로 탄성변형과 유사한 거동을 보여 정상 상태로 해석해도 무리가 없는 것으로 나타났다. 회복탄성계수에서 측정된 변위 결과를 처짐 탄성계수로 변환 후 1 SIGMA 단계를 적용하여 정상 처짐 탄성계수 범위를 산정하였다. $60^{\circ}C$에서의 파손 의심 처짐 범위와 하중-변위 선도 개형으로 포장 내부 상태를 예측하였다. 정상 표면처짐 구간인 $140{\mu}m$의 일부 구간에서 수분 침투 및 접착성능 저하가 관찰되었으나, 하중-변위 선도 개형에서 변곡점 발생 구간으로 확인되었다. 현장 확인 결과 제시된 기준은 높은 수준의 정확도를 보이는 것으로 나타났다.