• International Journal of Concrete Structures and Materials
• /
• v.11 no.1
• /
• pp.135-149
• /
• 2017

The prediction of the actual ultimate capacity of confined concrete columns requires partial confinement utilization under eccentric loading. This is attributed to the reduction in compression zone compared to columns under pure axial compression. Modern codes and standards are introducing the need to perform extreme event analysis under static loads. There has been a number of studies that focused on the analysis and testing of concentric columns. On the other hand, the augmentation of compressive strength due to partial confinement has not been treated before. The higher eccentricity causes smaller confined concrete region in compression yielding smaller increase in strength of concrete. Accordingly, the ultimate eccentric confined strength is gradually reduced from the fully confined value $f_{cc}$ (at zero eccentricity) to the unconfined value $f^{\prime}_c$ (at infinite eccentricity) as a function of the ratio of compression area to total area of each eccentricity. This approach is used to implement an adaptive Mander model for analyzing eccentrically loaded columns. Generalization of the 3D moment of area approach is implemented based on proportional loading, fiber model and the secant stiffness approach, in an incremental-iterative numerical procedure to achieve the equilibrium path of $P-{\varepsilon}$ and $M-{\varphi}$ response up to failure. This numerical analysis is adapted to assess the confining effect in rectangular columns confined with conventional lateral steel. This analysis is validated against experimental data found in the literature showing good correlation to the partial confinement model while rendering the full confinement treatment unsafe.

• The Journal of Korean Academy of Prosthodontics
• /
• v.50 no.2
• /
• pp.119-127
• /
• 2012

Purpose: This study was performed to compare the stress distribution pattern of abutment-fixture connection area using 3-dimensional finite element model analysis when 5 different implant systems which have internal connection. Materials and methods: For the analysis, a finite element model of implant was designed to locate at first molar area. Stress distribution was observed when vertical load of 200 N was applied at several points on the occlusal surfaces of the implants, including center, points 1.5 mm, 3.0 mm away from center and oblique load of 200 N was applied $30^{\circ}$ inclined to the implant axis. The finite element model was analyzed by using of 3G. Author (PlassoTech, California, USA). Results: The DAS tech implant (internal step with no taper) showed more favorable stress distribution than other internally connected implants. AS compare to the situations when the loading was applied within the boundary of implants and an oblique loading was applied, it showed higher equivalent stress and equivalent elastic strain when the loading was applied beyond the boundary of implants. Regardless of loading condition, the abutments showed higher equivalent stress and equivalent elastic strain than the fixtures. Conclusion: When the occlusal contact is afforded, the distribution of stress varies depending on the design of connection area and the location of loading. More favorable stress distribution is expected when the contact load was applied within the diameter of fixtures and the DAS tech implant (internal step with no tapering) has more benefits than the other design of internally connected implants.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.04a
• /
• pp.33-38
• /
• 2004

The ocean loading displacement of the crust is one of the major error sources in space geodesy techniques. In the western part of the Korean Peninsula, the vertical displacement due to ocean loading reaches up to 3cm. To check out the possibility of correcting the inaccurate ocean tide model in the Yellow Sea, we used four GPS sites to compute the height variations and compared them with the model-predicted ones. The comparison shows relatively good agreement except for small differences in the phase and amplitude.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2057-2063
• /
• 2011

Recently, concrete slab track is mostly used to satisfy requirements for safety of high-speed train operation and economical efficiency of maintenance. Due to structural characteristics of ballast track structures, roadbeds under the ballast experience a state of high stress. In case of slab track structures, however, its roadbeds place on a condition of low stress less than roadbeds of ballast track structures as increasing of the loading area. In this study, vertical earth pressure under slab track structures was investigated through real-scale loading tests and theoretical analysis to compare with each other.

• Earthquakes and Structures
• /
• v.11 no.2
• /
• pp.315-326
• /
• 2016

This paper presents the results of cyclic loading tests on concrete beams reinforced with various reinforcement, including ordinary steel bars, CFRP bars and CFRP prestressed concrete prisms(PCP). The main variable in the test program was the level of prestress and the cross section of PCP. The seismic performance indexes including hysteretic loops, skeleton curve, ductility, energy dissipation capacity and stiffness degradation were analyzed. The results show that the CFRP prestressed concrete prisms as flexural reinforcement of concrete beams has good seismic performance. And the ductility and the energy dissipation capacity were good, the hysteresis loops were full and had large area.

• Journal of the Society of Disaster Information
• /
• v.12 no.1
• /
• pp.40-46
• /
• 2016

Nowdays, adjacent loading bringing enormous harm to the existing bridge in engineering construction. In this paper, the influencing mechanism of adjacent loading to pier and Law of displacement of pier is researched through living examples, and the safe influence area has been defined. Research shows that: the main damages to piers is caused by the side loading; lateral displacement index of pier top surface is more conservative than the pier additional stress index; it is secure when the distance of adjacent load is 0.5 times of the height of accumulation or 6m, otherwise it would be very scary, and the monitoring measure is necessary.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.5
• /
• pp.131-139
• /
• 2004

In this study, on-site sewage treatment tests were conducted using the Absorbent Biofilter System (ABS) under different hydraulic loading rates to examine its treatment characteristics and efficiencies and to determine its feasibility as a small on-site sewage treatment system in a rural area. Results showed that the removal rates of BOD and SS were satisfactory at hydraulic loading rates of 100~150 cm/day, meeting the Korean effluent water quality standards for the riparian zone (10 mg/L). In the case of nutrients (N, P), however, the system did not perform well, necessitating further improvement for nutrient removal. A comparative analysis indicated that as a small on-site sewage treatment system, the ABS would be more suitable than other treatment systems in terms of performance stability, maintenance requirement, and cost-effectiveness and could be applied as an alternative treatment system in Korean rural areas.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.18-21
• /
• 2004

This paper discusses how steel cord and PVA hybrid fibers enhance the performance of high performance fiber reinforced cementitious composites (HPRFCC) in terms of elastic limit, strain hardening response and post peak of the composites. The effect of microfiber(PVA) blending ratio is presented. For this purpose flexure, direct tension and split tension tests were conducted. It was found that HFRCC specimen shows multiple cracking in the area subjected to the greatest bending tensile stress. Uniaxial tensile test confirms the range of tensile strain capacity from 0.5 to $1.5\%$ when hybrid fiber is used. The cyclic loading test results identified a unique unloading and reloading response for this ductile composite. Cyclic loading in tension appears not to affect the tensile response of the material if the uniaxial compressive strength during loading is not exceeded.

• Economic and Environmental Geology
• /
• v.30 no.3
• /
• pp.231-240
• /
• 1997

The behavior of rocks and microcrack development due to fatigue stresses are investigated using cyclic loading tests and ultrasonic velocity measurements. Twenty six medium-grained granite samples from the Pochon area are selected for measurements. Ultrasonic velocities are measured for samples before fatigue test to characterize the pre-existing microcracks. Then, thirteen different cycles of loadings with 70% and 80% dynamic strength are applied to the samples. The ultrasonic velocities are measured again to compare velocities after applications of fatigue stress with those before applications of fatigue stress. The results show that most microcracks are developed along the direction parallel to the axis of loading and that the amount of microcracks increases, as loading levels and numbers of cycle increase.

• Journal of the Korean Society of Safety
• /
• v.19 no.3 s.67
• /
• pp.78-83
• /
• 2004

The channel-type lining board that partial welded on many partition frames is used to normal servicing lining board type. On this study is to investigate existing channel-type lining board's capacity by using the static loading test. From this study, to develop new-type lining board which reflect well cross section area and sectional modulus of existing channel-type lining board. Six types FEM model are adopted. The accumulated test results of stress conditions and deflections by section shapes will be used to analyzed the relation between the capacity and the section shape. With the comparing the results of static loading test and FEM analysis.