• Magazine of the Korea Concrete Institute
• /
• v.9 no.1
• /
• pp.183-194
• /
• 1997

Traditional displacmir~nt measurement included an extrancous and cvrntlc. portmn due to test setup and support crushing. The magnitudc of this erroneous deformation was found to be of the same order as the actual displacement, leading to inaccurate determinations of fracture parameters. To overcome this problem, the load-CMOD relationship is a more reliable parameter for determining the fracture characteristics because it is unaffected by the specimen setup and any support crushing. An important step towards the use of load-(:MOD concept as a key fracture parameter depends on relating the CMODto the traditional load-line deflection. This investigation found that there was an unique linear relationship between the CMOD and the load-line deflection. The exact numeric value of relationship between the CMOD and the deflection. that is, the slope ofthe line, is discovered to be a material property. The relationship finds a problem with the existing IZIL,EM recommendations for. measuring the fracture energy of concrete. A proposal to correct the problem is made.

• Steel and Composite Structures
• /
• v.26 no.5
• /
• pp.595-606
• /
• 2018

A calculation method was presented to calculate the deflection of GFRP-concrete-steel beams with full or partial shear connections. First, the sectional analysis method was improved by considering concrete nonlinearity and shear connection stiffness variation along the beam direction. Then the equivalent slip strain was used to take into consideration of variable cross-sections. Experiments and nonlinear finite element analysis were performed to validate the calculation method. The experimental results showed the deflection of composite beams could be accurately predicted by using the theoretical model or the finite element simulation. Furthermore, more finite element models were established to verify the accuracy of the theoretical model, which included different GFRP plates and different numbers of shear connectors. The theoretical results agreed well with the numerical results. In addition, parametric studies using theoretical method were also performed to find out the effect of parameters on the deflection. Based on the parametric studies, a simplified calculation formula of GFRP-concrete-steel composite beam was exhibited. In general, the calculation method could provide a more accurate theoretical result without complex finite element simulation, and serve for the further study of continuous GFRP-concrete-steel composite beams.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.537-542
• /
• 2000

Wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of STD-11 in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension. The deflection is the smallest at the speed of wire of 10.6m/min and the water specific resistivity of 5k$\Omega$.cm. The deflection is found to be decreased as increasing dwell time. But if the water pressure is high, it is found not to be changed after the vibration of 4sec. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, is observed for rough wire-cutting EDM of STD-11. This phenomena is found to be similar in spite of the change of EDM energy level. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.4 no.3
• /
• pp.38-44
• /
• 2013

Glass fiber reinforced plastic (GRP) pipes buried underground are attractive for use in harsh environments, such as for the collection and transmission of liquids which are abrasive and/or corrosive. In this paper, we present the result of investigation pertaining to the structural behavior of GRP flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, experimental and analytical studies are conducted. In addition, vertical ring deflection is measured by the field test and finite element analysis (FEA) is also conducted to simulate behavior of GRP pipe buried underground. Based on the results from the finite element analyses considering soil-pipe interaction the vertical ring deflection behavior of buried GRP pipe is predicted. In addition, analytical and experimental results are compared and discussed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.7 s.178
• /
• pp.1681-1688
• /
• 2000

A dynamic model for the prediction of surface topography in high speed end milling process is developed. In this model the effect of tool runout, tool deflection and spindle vibration were taken in to account. An equivalent diameter of end mill is obtained by finite element method and tool deflection experiment. A modal parameter of machine tool is extracted by using frequency response function. The tool deflection, spindle vibration chip thickness and cutting force were calculated in dynamic cutting condition. The tooth pass is calculated at the current angular position for each point of contact between the tool and the workpiece. The new dynamic model for surface predition are compared with several investigated model. It is shown that new dynamic model is more effective to predict surface topography than other suggested models. In high speed end milling, the tool vibration has more effect on surface topography than the tool deflection.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.4
• /
• pp.89-96
• /
• 2017

A cable tray is a structure made of metal or a non-combustible material that supports cables in the electrical wiring of buildings. Cable trays should be developed to meet the various requirements of the construction site. In this study, a design system was developed to calculate the maximum support load and the maximum deflection according to the cross-sectional shape of the cable tray. The cross-sections of cable trays were modeled by combining linear and arc elements, and cross-sectional characteristics such as the 2nd moment of area were calculated. The distributed load and the concentrated load were applied to the cable tray using the Euler beam theory, and then the deflection profiles and maximum stress were calculated. To verify the developed system, deflection distributions and maximum stresses for two types of cable trays were calculated and compared. The maximum deflection and maximum stress errors calculated from the developed system were found to be less than 4% compared with numerical analysis results.

• Restorative Dentistry and Endodontics
• /
• v.29 no.4
• /
• pp.346-352
• /
• 2004

The purpose of present study was to evaluate the polymerization shrinkage stress and cuspal deflection in maxillary premolars resulting from polymerization shrinkage of composites and compomers. Composites and compomers which were used in this study were as follows: Dyract AP, Z100, Surefil. Pyramid, Synergy Compact, Heliomolar, Heliomolar HB, and Compoglass F. For measuring of polymerization shrinkage stress, Stress measuring machine (R&B, Daejon, Korea) was used. One-way ANOVA analysis with Duncan's multiple comparison test were used to determine significant differences between the materials. For measuring of cuspal deflection of tooth, MOD cavities were prepared in 10 extracted maxillary premolars. And reduction of intercuspal distance was measured by strain measuring machine (R&B, Daejon, Korea) One-way ANOVA analysis with Turkey test were used to determine significant differences between the materials. Polymerization shrinkage stress is $\mathbb{\ulcorner}$Heliomolar, Z100, Pyramid < Synergy Compact Compoglass F < Dyract AP < Heliomolr HB, surefil$\mathbb{\lrcorner}$ (P < 0.05). And cuspal delfelction is $\mathbb{\ulcorner}$Z100, Heliomolar, Heliomolar HB, Synergy Compact Surefil. < Compoglass F < Pyramid, Dyract AP$\mathbb{\lrcorner}$ (P < 0.05). Measurements of ploymerization shrinkage stress and those of cuspal deflection of the teeth was different. There is no correlation between polymerization shrinkage stress and cuspal deflection of the teeth(p > 0.05).

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.04a
• /
• pp.141-148
• /
• 1998

The chloride attack of the top mat of reinforcing bars is a major cause of deterioration of comcrete deck of plate girder bridges. This is caused by a current design method which requires a top mat of reinforcing bars to resist a negative bending moment in bridge decks. In recently, empirical evidence has indicated that the top transverse reinforcing bars can patially or fully be eliminated without jeopardizing the structural integrity of a deck. So, one of the most efficient way to increase durability of concrete deck of bridges is the development of new design method that reduce or eliminate the top mat reinforcing bars, mad it is possible by the exact analysis that considering the negative bending moment reducing effect which introduced by relative deflection of plate girders. In this study, we develop the new bridge deck analysis method that considered the effect of relative girder deflection by applying the principles of slope deflection method of frames, and that is fine tuned with results of finite element analysis. This new approach evaluate a bending moment in a deck based on the effect of relative girder deflection as well as the magnitude of wheel loads, the girder spacing and stiffness, deck stiffness and the span length

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.39 no.1
• /
• pp.54-63
• /
• 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
• /
• v.61 no.1
• /
• pp.117-124
• /
• 2017

Load testing is one of the important tests to determine if the structural elements can be used at the intended locations for which they have been designed. It is nothing but gradually applying the loads and measuring the deflections and other parameters. It is usually carried out to determine the behaviour of the system under service/ultimate loads. It helps to identify the maximum load that the structural element can withstand without much deflection/deformation. It will also help find out which part of the element causes failure first. The load-deflection behaviour of the road bridge girder has been studied by carrying out the load test after simulating the field conditions to the extent possible. The actual vertical displacement of the beam at mid span due to the imposed load was compared with the theoretical deflection of the beam. Further, the recovery of deflection at mid span was also observed on removal of the test load. Finally, the beam was checked for any cracks to assert if the beam was capable of carrying the intended live loads and that it could be used with confidence.