• 한국농공학회지
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• 제39권1호
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• pp.54-63
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• 1997

The purpose of this study is to analyse deformation properties by carrying out of flexure experimentations after fabricating polymer concrete sandwich panels which are composed of the polymer concrete in facing and expanded polystyren in cores, and to provide the basic data necessary to design, fabricate and operate the structure using these polymer concrete sandwich panels The analysed result of this study is summarized as follows. 1. The result of experiment on flexural deflection indicated that the thicker the thickness of both cores and facing of the polymer concrete sandwich panels, the smaller the deflection but the larger the ultimate shear force. In addition, it was also shown that the thicker the thickness of these cores and facing, the smaller the increasing rate of the deflection with the increase of load. 2. The breaking shape of polymer concrete sandwich panels by experiment on flexure was different according to the thickness of facing. When the facing was 5mm in thickness, it was the flexure while it was the flexure and shear failure when the facing was 5mm in thickness. As a result, it seems that the thickness of the facing has a great effect on failure. 3. There were induced not only the related formula between load, deflection and deformation according to the thickness of cores and facing on the basis of the flexure experiment, but also formula between load, horizontal displacement, Then, it seems that it will be possible to estimate the above elements by using these related formulas.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.585-594
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• 2021

Ductility is very important parameter in seismic design of RC members such as beams where it allows RC beams to dissipate the seismic energy. In this field, the curvature ductility has taken a large part of interest compared to the deflection ductility. For this reason, the present paper aims to propose a general formula for predicting the deflection ductility factor of RC beams under mid-span load. Firstly, the moment area theorem is used to develop a model in order to calculate the yield and the ultimate deflections; then this model is validated by using some results extracted from previous researches. Secondly, a general formula of deflection ductility factor is written based on the developed deflection expressions. The new formula is depended on curvature ductility factor, beam length, and plastic hinge length. To facilitate the use of this formula, a parametric study on the curvature ductility factor is conducted in order to write it in simple manner without the need for curvature calculations. Therefore, the deflection ductility factor can be directly calculated based on beam length, plastic hinge length, concrete strength, reinforcement ratios, and yield strength of steel reinforcement. Finally, the new formula of deflection ductility factor is compared with the model previously developed based on the moment area theorem. The results show the good performance of the new formula.

• Structural Engineering and Mechanics
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• 제81권6호
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• pp.751-767
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• 2022

In the hogging bending moment area, continuous composite beams are subjected to the ultimate limit state of lateral-torsional buckling (LTB), which depends on web stiffness as well as concrete slab and shear connection stiffnesses. The design of the LTB and the determination of the elastic critical moment are produced approximately, using the European Standard EN 1994-1-1:2004, for continuous composite steel beams, but is applicable only for those with a plane web steel profile. Also, and from the previous researches, the elastic critical moment of the continuous composite beams with corrugated sinusoidal web steel profiles was determined. In this paper, a finite element analysis (FEA) model was developed using the ANSYS 16 software, to determine the elastic critical moments of continuous composite steel beams with various corrugated web profiles, such as trapezoidal, zigzag, and rectangular profiles, which were evaluated against numerical data of the sinusoidal one from the literature. Ultimately, the failure load of a composite steel beam with various web profiles was predicted by studying 46 models, based on FEA modeling, and a procedure for predicting the elastic critical moment of composite beams with various web steel profiles was proposed. When compared to sinusoidal web profiles, the trapezoidal, zigzag, and rectangular web profiles required an average increase in load capacity and stiffness of 7%, 17.5%, and 28%, respectively, according to the finite element analysis. Also, the rectangular web steel profile has a greater stiffness and load capacity. In contrast, the sinusoidal web has lower values for these characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.699-703
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• 2004

The autopilot system targets decreasing labor, working environment, service safety security and elevation of service efficiency. Ultimate purpose is minimizing number of crew for guarantee economical efficiency of shipping service. Recently, being achieving research about Course Keeping Control, Track Keeping Control, Roll-Rudder Stabilization, Dynamic ship Positioning and Automatic Mooring Control etc. which compensate nonlinear characteristic using optimizing control technique. And application research is progressing using real ship on actual field. Relation of Rudder angle which adjusted by Steering Machine and ship-heading angle are non-linear. And, Load Condition of ship acts as non-linear element that influence to Parameter of ship. Also, because the speed of a current and direction of waves, velocity and quantity of wind etc. that id disturbance act in non-linear form, become factor who make service of shipping painfully. Therefore, service system of shipping requires robust control algorithm that can overcome nonlinearity. In this paper, Using GA algorithm,design autopilot system of ship that could overcome the non-linear factor of ship and disturbance and examined result through simulation.

• Computers and Concrete
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• 제15권3호
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• pp.391-410
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• 2015

One of the most common applications of ferrocement is the manufacturing of thin stiffened plates which are prone to buckling. This study focuses on the investigation of the behavior of a ferrocement plate, stiffened in both directions by means of an appropriate grid of ribs. In the present paper detailed three-dimensional numerical Finite Element models are formulated for the simulation of the behavior of the structure under study, which are able to take into account both the geometric and material non-linearities that are present in the subject at hand (plasticity, cracking, large displacements). The difference among the formulated models lies on the use of different types of finite elements. The numerical results obtained by each model are compared and the most efficient model is determined. Finally, this model is in the sequel used for the further investigation of the effect of different parameters on the ultimate load capacity, such as the initial out-of-plane imperfection of the plate and the interaction between the axial loads in both directions.

• Advances in concrete construction
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• 제6권5호
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• pp.527-543
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• 2018

Crack control of precast members is crucial for durability. However, there is no clear provision to check the crack width of precast joints. This study presents an experimental investigation of loop joint details for use in a precast bridge deck system. High strength concrete of 130 MPa was chosen for durability and closer joint spacing. Static tests were conducted to investigate the cracking and ultimate behavior of test specimens. The experimental results indicate that current design codes provide reasonable estimation of the flexural strength and cracking load of precast elements with loop joint of high strength concrete. However, the crack width control of the loop joints with high strength concrete by the current design practices was not appropriate. Some recommendations to improve crack control of the loop joint were derived.

• Steel and Composite Structures
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• 제11권3호
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• pp.233-250
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• 2011

An experimental study has been carried out to reveal the shear-bond failure mechanism of composite deck slabs. Thirteen full scale simply supported composite slabs are studied experimentally, with the influence parameters like span length, slab depth, shear span length and end anchorage provided by steel headed studs. A dozen of strain gauges and LVDTs are monitored to capture the strain distribution and variation of the composite slabs. Before the onset of shear-bond slip, the longitudinal shear forces along the span are deduced and found to be proportional to the vertical shear force in terms of the shear-bond strength in the m-k method. The test results are appraised using the current design procedures. Based on the partial shear-bond connection at the ultimate state, an improved method is proposed by introducing two reduction factors to assess the moment resistance of a composite deck slab. The new method has been validated and the results predicted by the revised method agree well with the test results.

• 한국구조물진단유지관리공학회 논문집
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• 제21권1호
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• pp.9-14
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• 2017

본 연구는 일반철근과 FRPH Bar를 주철근으로 한 철근 콘크리트 보부재를 대상으로 정적실험 및 반복하중 재하실험을 수행하여 에너지 소산성능 및 반복하중 저항성능을 분석하였다. 실험을 위하여 24MPa의 설계강도를 가진 콘크리트 보부재($200{\times}200{\times}2175mm$)를 제작하였으며, 4점 휨 시험을 수행하여 초기균열하중, 항복하중, 파괴하중을 측정하였다. 정적하중 재하실험을 통해 각 시험체에 대한 항복하중과 파괴강도를 측정하였는데, 항복하중은 RC보에서는 48.9kN, FRPH 보에서는 36kN으로 평가되었으며, 파괴하중은 두 시험체 모두 50kN의 강도를 보였다. 정적하중-처짐 결과에서는 FRPH 보는 RC보에 비하여 인장경화특성을 나타내는데, 이는 FRPH bar의 인장경화 특성에 기인한다. 반복하중하에서 FRPH bar를 가진 보에서는 일반 RC보와는 다르게 작은 폭의 균열이 넓게 발생하였으며, 우수한 처짐 복원력을 나타내었다. 정적 동적 에너지 비율을 이용한 에너지 소산능력에서는 RC보에서는 0.62, FRPH 보에서는 0.83으로 평가되었으며, 이를 통해 FRPH를 가진 보부재에서 효과적으로 반복하중에 대하여 저항함을 알 수 있다.

• Steel and Composite Structures
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• 제25권4호
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• pp.457-472
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• 2017

The objective of this paper is to investigate the flexural behavior of concrete-filled round-ended steel tubes (CFRTs) under bending. Beam specimens were tested to investigate the mechanical behavior of the CFRTs, including four CFTs with different concrete strengths and steel ratios, and three CFRTs with varied aspect ratios. The load vs. deflection relationships and the failure modes for CFRTs were analyzed in detail. The composite action between the core concrete and steel tube was also discussed and examined based on the experimental results. In addition, ABAQUS program was used to develop the full-scale finite element model and analyze the effect of different parameters on the moment vs. curvature curves of the CFRTs bending about the major and minor axis, respectively. Furthermore, design formulas were proposed to estimate the ultimate moment and the flexural stiffness of the CFRTs, and the simplified theoretical model of the moment vs. curvature curves was also developed. The predicted results showed satisfactory agreement with the experimental and FE results. Finally, the differences of the experimental, FE and predicted results using the existing codes were illustrated.

• Steel and Composite Structures
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• 제22권4호
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• pp.821-835
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• 2016

The paper presents an experimental study of the structural behavior of circular flyash-concrete-filled steel tubular stub columns under axial compressive loads. In this study, 90% and 100% by weight of the cement in the concrete core was replaced with flyash. Twenty-seven specimens were tested to study the influence of flyash content, wall thickness of the steel tube, and curing age on the ultimate capacity and confinement effect. The experimental results were compared with the design values calculated using AISC-LRFD (1999), ACI (1999), AIJ (1997) and Eurocode 4 (1994). From the experimental study, it was determined that the confinement effect of circular steel tubes filled with high content flyash concrete was better than that of specimens filled with ordinary Portland cement concrete. The 5.88-mm-thick steel tube filled with 100% flyash concrete was equivalent in strength to a steel tube filled with C30 concrete at 28 days.