• Earthquakes and Structures
• /
• v.27 no.4
• /
• pp.251-262
• /
• 2024

To improve the seismic behavior of composite column with high strength concrete-filled steel tubular in bridge engineering, four column specimens, including one specimen with vertical prestressing force and three specimens with tri-directional prestressing force, were conducted under low cyclic loading. Test parameters including axial compression ratio, degree of vertical prestressing and existence of prestressed steel strips were emphatically analyzed. Experimental results revealed that applying tri-directional prestressing force to column with high strength concrete-filled steel tubular produced more beneficial behavior in terms of ductility, energy-dissipation and self-centering capacity over that of specimens only with vertical prestress. Moreover, ultimate bearing capacity of composite column was improved with increase of degree of vertical prestress and external axial force, while ductility would be reduced. External axial force showed slight influence on the self-centering behavior. Finally, a calculation equation for predicting the shear capacity of the tri-directional prestressed composite column was proposed and the accuracy of the calculated results validated by experimental data.

• The KIPS Transactions:PartD
• /
• v.18D no.2
• /
• pp.143-148
• /
• 2011

In this paper developed a wearable activity device and algorithm which can be converted into the real-time activity and monitoring by acquiring sensor row data to be occurred when a person is walking by using a tri-axial accelerometer. Test was proceeded at various step speeds such as slow walking, walking, fast walking, slow running, running and fast running, etc. for 36 minutes in accordance with the test protocol after wearing a metabolic test system(K4B2), Actical and the device developed in this study at the treadmill with 59 participants of subjects as its target. To measure the activity of human body, a regression equation estimating the Energy Expenditure(EE) was drawn by using data output from the accelerometer and information on subjects. As a result of experiment, the recognition rate of algorithm being proposed was shown the activity conversion algorithm was enhanced by 1.61% better than the performance of Actical.

• PNF and Movement
• /
• v.11 no.2
• /
• pp.31-40
• /
• 2013

Purpose : The purpose of this study was to measure the center of mass in body with stroke patients using a tri-axial accelerometer during walking. Methods : Twenty-eight patients were recruited and divided into two groups for this study. To measure their walking ability, Timed Up & Go (TUG) test and Fucntioanl Gait Assessment (FGA) were conducted and acceleration at rotation of center of mass (COM) in body were measure for each group. Results : In the comparisons between the two groups, the TUG and FGA were not significant differences and acceleration at rotation of COM was not significant differences also. Conclusion : Our research results suggesting that the accelerometer may be used as a testing tool and ongoing assessment tool for stroke patients during effects of intervention in walking.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.6
• /
• pp.539-545
• /
• 2016

UPS system in the liquefied natural gas(LNG) receiving terminal is one of the fundamental equipment that need to sustain operation during earthquake. In this study, modal identification test of UPS system was performed based on IEEE Std. 693-2005 and natural frequencies and modal damping, mode shapes had been identified. In addition, tri-axial time history test was performed to check the behavior and stress of the equipment during earthquake. Eigenvalue analysis was performed and analysis model was modified by reflecting the results of the test. Static analysis by dead weight and response spectrum analysis were performed to compare the combined stresses with the stress results of test. Dynamic characteristics and combined stresses under seismic load condition of the improved analysis model were similar to the test results and in this regard the compatibility was proved.

• Journal of the Korean Society of Safety
• /
• v.21 no.2 s.74
• /
• pp.89-97
• /
• 2006

Recently, experimental and theoretical studies about nonlinear behavior of large concrete structures are in progress. The purpose of this study is to describe the nonlinear behavior of a concrete specimen under compression using several plastic models and to choose the best plastic model for later use in numerical analyses of concrete structures. ABAQUS is a general-purpose FEM program and we tested all suitable embedded material models for concrete. To verify the effectiveness of nonlinear analyses, results were compared with uniaxial and triaxial compression test results.

• Journal of the Korea Concrete Institute
• /
• v.16 no.4 s.82
• /
• pp.501-509
• /
• 2004

The proposed model can predict the compressive behaviors of concrete confined with fiber reinforced polymer (FRP) jacket. To model confining concrete by FRP jackets, the hypoelasticity-based constitutive law of concrete In tri-axial stress states has been presented. The increment of strength of concrete has been determined by the failure surface of concrete in tri-axial states, and its corresponding peak strain is computed by the strain enhancement factor that is proposed in the present study, Therefore, the newly proposed model is a load-dependent confinement model of concrete wrapped by FRP jackets to compare the previous models which are load-independent confinement models. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimension. The developed model is implemented into the incremental analysis of compressive tests. The verification study with several different experiments shows that the model is able to adequately capture the behavior of the compression test by including better estimations of the axial responses as well as the lateral response of FRP-confined concrete cylinders.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.4
• /
• pp.89-98
• /
• 2010

Recently, many researches on bottom ash which is produced in the burning process of power plant are actively performed for its utilization for soil-subbase materials. In this paper, bottom ashes from 5 different power plants are prepared and several tests including compaction, CBR, and tri-axial compression are carried out for mixed bottom ash and weathered soil considering 3 replacement ratio of 30%, 50%, and 70%. Through the tests, CBR result over 20 are evaluated without plastic property, which shows availability of subbase material. With higher increase in replacement ratio of bottom ash, CBR of mixed soil increases due to the higher mechanical performance of bottom ash. However, replacement effects of bottom ash on friction angle and cohesion are evaluated to be little since bottom ash plays a little role in rearrangement of mixed soil. Bottom ash with a good mechanical property is evaluated to have reasonable bearing capacity which shows a good property for subbase materials.

• Nuclear Engineering and Technology
• /
• v.55 no.11
• /
• pp.4252-4265
• /
• 2023

In the case of nuclear power plants near end of their design life, a reassessment of the performance of safetyrelated equipment may be necessary to determine whether to shut down or extend the operation of the power plant. Therefore, it is necessary to evaluate the level of performance decline due to degradation. Electrical cabinets, including MCC and switchgear, are representative safety-related equipment. Several studies have assessed the degradation and seismic performance of nuclear power plant equipment. Most of those researches are limited to individual components due to the size of safety-related equipment and test equipment. However, only a few studies assessed the degradation performance of electrical cabinets. The equipment of various nuclear power plants is anchored to concrete foundations, and crack in concrete foundations is one of the most representative of degradation that could be visually confirmed. However, it is difficult to find a study for analysis through testing the effect of cracks in concrete foundations on the response of electrical cabinet internal equipment fixed by anchors. In this study, using a simple cabinet model considering cast-in-place anchor in uncracked and cracked concretes, a tri-axial shaking table tests were performed and the seismic behavior were observed.

• Smart Structures and Systems
• /
• v.12 no.6
• /
• pp.661-678
• /
• 2013

In this paper, a wireless sensing system for structural field evaluation and rating of bridges is presented. The system uses a wireless platform integrated with traditional analogue sensors including strain gages and accelerometers along with the operating software. A wireless vehicle position indicator is developed using a tri-axial accelerometer node that is mounted on the test vehicle, and was used for identifying the moving truck position during load testing. The developed software is capable of calculating the theoretical bridge rating factors based on AASHTO Load and Resistance Factor Rating specifications, and automatically produces the field adjustment factor through load testing data. The sensing system along with its application in bridge deck rating was successfully demonstrated on the Evansville Bridge in West Virginia. A finite element model was conducted for the test bridge, and was used to calculate the load distribution factors of the bridge deck after verifying its results using field data. A confirmation field test was conducted on the same bridge and its results varied by only 3% from the first test. The proposed wireless sensing system proved to be a reliable tool that overcomes multiple drawbacks of conventional wired sensing platforms designed for structural load evaluation of bridges.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.11
• /
• pp.129-136
• /
• 2019

Non-structural elements are vulnerable to earthquake ground motion. In this study, an experimental study for the electrical non-structural element was performed using tri-axial shaking table tests. A 100kVA UPS(Uninterruptible Power Supply system) was used as the test specimen. The test specimen was anchored to the concrete slab using the conventional installation detail. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration with respect to the required response spectrum defined in ICC-ES AC156 were from 25% to 600%. Based on the test results, damage and dynamic characteristics of UPS were evaluated and analyzed including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement.