• 한국지반신소재학회논문집
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• 제15권4호
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• pp.89-96
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• 2016

인천 ${\bigcirc}{\bigcirc}$지역의 연약지반에 시공된 변단면 연약지반보강기초(Variable cross-section soft ground reinforced foundation)의 연직압축거동을 분석하였다. 변단면 연약지반보강기초는 원지반과 고화재를 혼합교반하여 형성되는 고형체의 높은 강성과 강도를 이용하여 상부구조물로부터 유발되는 연약하중을 효과적으로 저항하기 위하여 시공된다. 변단면 연약지반보강기초는 군말뚝 형식으로 시공이 되는데, 정확한 연직거동을 알기 위하여 1개소의 기초에 대한 연직재하시험을 수행하였다. 변단면 연약지반보강기초의 거동을 일반적인 깊은 기초의 거동과 비교하기 위하여 유사한 천층지반조건에 시공된 PHC 파일의 재하시험 결과와 비교하여 재하하중에 따른 침하량 및 하중전이 거동특성을 분석하였다. 연직재하시험결과를 비교분석하였다. 변단면 연약지반보강기초는 제한된 범위의 연직하중에 대하여 천층에서도 효율적으로 저항하는 것으로 분석되었다.

• Structural Engineering and Mechanics
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• 제18권4호
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• pp.493-516
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• 2004

This paper addresses the behavior and strength of structural walls with a concrete compressive strength exceeding 69 MPa. This information also enhances the current database for improvement of design recommendations. The objectives of this investigation are to study the effect of axial-load ratio on seismic behavior of high-strength concrete flexural walls. An analysis has been carried out in order to assess the contribution of deformation components, i.e., flexural, diagonal shear, and sliding shear on total displacement. The results from the analysis are then utilized to evaluate the prevailing inelastic deformation mode in each of wall. Moment-curvature characteristics, ductility and damage index are quantified and discussed in relation with axial stress levels. Experimental results show that axial-load ratio have a significant effect on the flexural strength, failure mode, deformation characteristics and ductility of high-strength concrete structural walls.

• Structural Engineering and Mechanics
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• 제44권6호
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• pp.753-762
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• 2012

The ratcheting characteristics of cylindrical shell under cyclic axial loading are investigated. The specimens are subjected to stress-controlled cycling with non-zero mean stress, which causes the accumulation of plastic strain or ratcheting behavior in continuous cycles. Also, cylindrical shell shows softening behavior under symmetric axial strain-controlled loading and due to the localized buckling, which occurs in the compressive stress-strain curve of the shell; it has more residual plastic strain in comparison to the tensile stress-strain hysteresis curve. The numerical analysis was carried out by ABAQUS software using hardening models. The nonlinear isotropic/kinematic hardening model accurately simulates the ratcheting behavior of shell. Although hardening models are incapable of simulating the softening behavior of the shell, this model analyzes the softening behavior well. Moreover, the model calculates the residual plastic strain close to the experimental data. Experimental tests were performed using an INSTRON 8802 servo-hydraulic machine. Simulations show good agreement between numerical and experimental results. The results reveal that the rate of plastic strain accumulation increases for the first few cycles and then reduces in the subsequent cycles. This reduction is more rapid for numerical results in comparison to experiments.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.373-380
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• 2002

In this study, In order to compare the behavior of axail load transfer for S.L. coated piles and uncoated piles installed at a field test site. During static pile load tests, axial load transfer for S.L. coated piles and uncoated piles were measured.

• 한국소음진동공학회논문집
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• 제16권11호
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• pp.1115-1123
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• 2006

Nuclear fuel rods are exposed to axial flow in a reactor, and flow-induced-vibration due to the flow usually causes damage in the fuel rods. Thus a prior knowledge about dynamic behavior of a fuel rod exposed to the flow condition should be provided. This paper shows that dynamic characteristics of a nuclear fuel rod depend on axial flow velocity. Assuming small lateral displacement, the effects of uniform axial flow are investigated. The analytic results show that axial flow generally reduces fuel rod stiffness and raises its damping in normal condition. Also, the critical axial velocities which make the fuel rod behavior unstable were found. That is, solving generalized eigenvalue equation of the fuel rod dynamic system, the eigenvalues with positive real part are detected. Based on the simulation results, on the other hand, it turns out that the ordinary axial flow in nuclear reactors does not affect to stability of a nuclear fuel rod even in the conservative condition.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.31-34
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• 2005

An experimental investigation was conducted to examine the hysteric behavior of Ultra-High strength concrete columns for the requirement of ACI provision. Seven 1/3 scaled columns were fabricated to simulate an 1/2 story of actual structural members with the cross section $300\times300mm$ and the shear span ratio 4. The main variables are axial load ratio, configuration and volumetric ratio of transverse reinforcement. It has been found that the behavior of columns was affected by axial load ratio rather than the amount and the configuration of transverse reinforcement. Consequently, to secure the ductile behavior of 100MPa Ultra-High strength concrete columns, ACI provision for the requirement of transverse steel may considered axial level and the detail of transverse reinforcement.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.251-258
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• 2003

This study is to understand the characteristics of axial force behavior that operates to the part of continuous welded rail and to investigate the basic data for secure the structure's stability and retrofit of the track. To develop the FEM model that type of plate girder which is used in the domestic national railway among servicing railway type. It is to analyze the characteristics of axial force behavior according to equip of the expansion joint and support placing by using the axial force simulation in making the continuous welded rail. As the result of research on the parametric valuables through the analysis, it is investigated that 'FMFM type' is more efficient than the other support type. Also, it conclude that structures are having the expansion joint is the most safe condition.

• 콘크리트학회논문집
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• 제11권4호
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• pp.55-62
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• 1999

When stress is beyond elastic limit or cracks occur in a reinforced concrete member subjected to axial force and biaxial bending, curvature about each principal axis of uncracked section is influenced by axial force and bending moments about both major and minor principal axes. It is mainly due to the translation and rotation of principal axes of the cross section after cracking. Recently, by considering these effects, a numerical method predicting the behavior of concrete columns subjected to axial force and biaxial bending was proposed. In this study, in order to verify the proposed numerical method and investigate the effects of cracking on the behavior of reinforced concrete columns, a series of tests were carried out for 16 tied reinforced concrete columns with 100×100 mm square and 200×100 mm rectangular sections under various loading conditions. The angle between the direction of eccentricity and the major principal axis of uncracked section were 0, 30, 40° for the square section and 0, 30, 45, 60, 90° for the rectangular section, respectively. A comparison between numerical predictions and test results shows good agreements in ultimate loads, axial force-lateral deflection relations, and lateral deflection trajectories. It is also found, in this limited investigation, that the ACI's moment magnifier method is conservative in both uniaxial and biaxial loading conditions.

• Structural Engineering and Mechanics
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• 제72권1호
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• pp.43-60
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• 2019

This paper presents a finite element model which can simulate the axial compression behavior of steel reinforced recycled concrete (SRRC) filled square steel tube columns using the ABAQUS software. The analytical model was established by selecting the reasonable nonlinear analysis theory and the constitutive relationship of material in the columns. The nonlinear analysis of failure modes, deformation characteristics, stress nephogram, and load-strain curves of columns under axial loads was performed in detail. Meanwhile, the influences of recycled coarse aggregate (RCA) replacement percentage, profile steel ratio, width thickness ratio of square steel tube, RAC strength and slenderness ratio on the axial compression behavior of columns were also analyzed carefully. It shows that the results of finite element analysis are in good agreement with the experimental results, which verifies the validity of the analytical model. The axial bearing capacity of columns decreased with the increase of RCA replacement percentage. While the increase of wall thickness of square steel tube, profile steel ratio and RAC strength were all beneficial to improve the bearing capacity of columns. Additionally, the parameter analysis of finite element analysis on the columns was also carried out by using the above numerical model. In general, the SRRC filled square steel tube columns have high bearing capacity and good deformation ability. On the basis of the above analysis, a modified formula based on the American ANSI/AISC 360-10 was proposed to calculate the nominal axial bearing capacity of the columns under axial loads. The research conclusions can provide some references for the engineering application of this kind of columns.

• 한국구조물진단유지관리공학회 논문집
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• 제13권2호통권54호
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• pp.215-222
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• 2009

콘크리트 공시편의 외부보강을 위해서 강판과 FRP 자켓을 이용하였다. 기존의 강판 또는 FRP 자켓 보강기법은 보강재와 콘크리트 사이에 접착제를 이용하여 시공하므로 콘크리트와 보강재가 합성거동 하게 된다. 그러나 본 연구에서 사용한 강판 보강기법은 외부압착에 의한 기법으로 강판과 콘크리트가 합성거동을 하지 않는다. 본 연구에서는 비합성거동과 합성거동을 하는 보강된 콘크리트 시편의 압축 변형률의 측정과 이를 보정하는 기법을 제시하였다. 비합성거동의 강판보강 콘크리트 시편의 압축변형률 측정은 강판의 표면에서 변형률을 측정하여 표시할 수 없으며, 시편에 설치하여 측정하는 compressometer를 사용할 수도 없었다. 따라서 시편의 상하단에 두꺼운 판을 설치하여 두 판사이의 변형을 측정한 후. 이를 압축변형률로 변환하였다. 합성 거동을 하는 FRP 보강의 경우는 FRP 튜브 표면에서 측정되는 수직방향의 변형률을 콘크리트의 압축변형률로 사용이 가능하다. 그러나 튜브 표면의 수직변형률은 시편의 부풀음에 의한 인장변형률이 포함되어 있기 때문에 콘크리트의 압축변형률을 추정하기 위해서는 이를 보정하여야 한다. 보정된 압축변형률은 콘크리트 내부에서 측정한 변형률과 기존의 콘크리트 연속체 모델과 비교하였을 때, 만족한 결과를 보였다. 보정 전의 응력-변형률 곡선은 콘크리트의 연성거동 및 에너지 소산능력을 보정 전에 비해 낮게 평가할 위험성이 있다.