• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.21-28
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• 2002

Ductile behavior and strength of concrete-filled steel(CFS) piers was supported by many quasi-static cyclic loading tests. This test method, however, only estimates the member′s deformation capacity under escalating and repetitive displacement and ignores dynamic and random aspects of an earthquake load. Therefore, to understand complete seismic behavior of the structure against an earthquake, dynamic tests such as shaking table test and pseudo-dynamic tests are required as well as quasi-static tests. In this paper, following "Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loadint Test", the seismic behavior of CFS and steel piers designed for I-Soo overpass in Seoul in investigated by the pseudo-dynamic test. In addition, the residual strength of both piers after an earthquake is estimated by the quasi-static test. The results show that both piers have satisfactory ductility and strength against well-known EI Centro earthquake although the CFS pier has better strength and energy dissipation than the steel pier.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.113-118
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• 1998

The relation of cycle loading to deflections on the mid-span, the crack propagation and the modes of failure according to cycle number, fatigue life and S-N curve were observed through the fatigue test. Based on the fatigue test results, high-strength reinforced concrete beams failed to 57 ~ 66 percent of the static ultimate strength. Fatigue strength about two million cycles from S-N curves was certified by 60 percent of static ultimate strength.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.2
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• pp.115-123
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• 2022

Purpose : The hamstring is a group of three muscles, biceps femoris, semitendinosus, and semimembranosus, placed behind the thigh. The hamstring is one of the most commonly injured muscles and usually occurs during high-speed, high-intensity exercise. The purpose of this study was to investigate the effect of static stretching and eccentric exercise of hamstrings on flexibility, strength, and functional performance. Methods : This study was conducted on 28 healthy adults. Subjects were divided into a static stretching group (n=15) and an eccentric exercise group (n=13). Subjects measured hamstring flexibility (active knee extension test), hamstring strength (concentric and eccentric peak torque), and functional performance (triple hop for distance and modified 20 m sprint). The intervention was conducted three times a week for six weeks. To compare the difference between values before and after the intervention, paired t-test was used, and an independent t-test was used to compare between groups. Results : In both groups, the active knee extension test, concentric peak torque, triple hop test, and 20 m sprint significantly increased after the intervention compared to before the intervention (p<.05). However, no significant difference was found in eccentric peak torque after intervention in both groups (p>.05). No significant difference was found between the two groups in the effect on the variables (p>.05). Conclusion : Both interventions were found to be effective for flexibility, concentric strength, and functional performance. Eccentric exercise and static stretching are recommended to improve the flexibility and functional performance of the hamstring. This study's results will be considered essential data on the effectiveness of static stretching and eccentric exercise.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.467-470
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• 2005

This study was performed to evaluate the static strength of long-span PSC deck slabs. In the previous study, the minimum thickness of PSC deck slabs in the composite two-girder bridge was proposed. To examine the structural behavior and safety of the PSC deck slabs designed in accordance with the proposed minimum thickness, 1/3 scaled PSC deck slabs in the composite two-girder bridge were tested under the static loading. The test results were compared with the predicted values proposed by the code and Matsui. Test results showed ultimate static strength of the PSC deck slabs designed in accordance with the proposed minimum thickness have enough margin of safety. The static failure mode of each test specimen was punching shear mode.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.69-75
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• 2017

Structural safety evaluation for static strength of thin plate RC member with high strength concrete is conducted in this study. Static strengths were predicted and compared with the experimental values. Predicted values were calculated by the evaluation formula based on the punching shear behavior and the yield line theory which can appear in the plate members. Static load tests were carried out for the specimens with high strength concrete and the test results were compared with the required performance in design. The comparison results show that the specimens with high strength concrete have sufficient structural safety for flexural and punching shear performance required in design. High strength concrete specimens exhibited excellent strength despite their small thickness. The range of concrete strengths applied in this study was about 60 MPa to 100 MPa.

• Steel and Composite Structures
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• v.24 no.5
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• pp.615-633
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• 2017

Fatigue crack initiated in welded tubular joints due to cyclic loading may produce harmful effect on the integrity of the tubular structures. To study such effect, both fatigue and static tests on nine circular tubular T-joint specimens made of carbon steel materials were carried out. The specimens were subjected to tensile loading in both fatigue and static tests. The load-displacement relation, the crack propagation and the failure mode of the specimens are all analyzed. The deterioration of the static strength of the cracked T-joints is also investigated and evaluated through an area reduction factor. Experimental results indicate that the static strength of a tubular T-joint with a surface crack seems to decrease slightly while a through crack has relatively remarkable effect on the reduction of the static strength. Additionally, experimental results also show that the toughness of the materials and the geometry of the specimens play an important role on the failure process of cracked tubular T-joints.

• Proceedings of the KSR Conference
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• 2003.10a
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• pp.187-191
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• 2003

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

• Journal of Welding and Joining
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• v.23 no.1
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• pp.35-40
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• 2005

In this paper, static and fatigue load tests for the specimens, components and carbody were carried out to investigate the strength of welded joints in aluminum rolling stock. Tensile test results showed that the static strength of welded joint for the heat-treated alloy is reduced significantly and fatigue strength data are scattered by the welding imperfections. Component and whole carbody fatigue test results showed agreements with the design fatigue strength standards for specimens of the same joint detail. Test results revealed that full penetration welding and strict management of welding procedure are crucial for securing the strength of welded joint in aluminum carbody.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.780-788
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• 2009

AE technique was applied to the static structural test of the composite wing structure to evaluate the structural integrity and damage. During the test, strain and displacements measurement technique were used to figure out for static structural strength. AE parameter analysis and source location technique were used to evaluate the internal damage and find out damage source location. Design limit load test, the 1st and 2nd design ultimate load tests and fracture test were performed. Main AE source was detected by an sensor attached on skin near by front lug. Especially, at the 1st design ultimate test, strain and displacements results didn't show internal damage but AE signal presented a phenomenon that the internal damage was formed. At the fracture test, AE activities were very lively, and strain and displacements results showed a tendency that the load path was changed by severe damage. The internal damage initiation load and location were accurately evaluated during the static structural test using AE technique. It is certified from this paper that AE technique is useful technique for evaluation of internal damage at static structural strength test.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.7-12
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• 2003

When the wind turbine is used in cold regions, the mechanical properties and dimension stability of the blade will be changed. The proposal of this paper is to test the durability of the blade for wind turbine. It is necessary to select the most comfortable materials and fabrication processes for more stable wind turbine blade in cold regions. To select the most comfortable materials and processes, the static strength has to know through the tensile static tests at the severe condition as cold regions. First, the tensile static specimens made by RIM (Resin injection molding) process & vacuum bagging process with reinforcement materials and resin. Tensile static tests were carried out on three laminate lay-ups (carbon prepreg, carbon fiber dry fabric and glass fiber dry fabric) at different test temperature($24^{\circ}$, $-30^{\circ}$), determining properties such as the mechanical strength, stiffness and strain to failure. At different test temperature, in order to test the tensile strengths of these specimens used the low temperature chamber. Next, the results of this test were compared with each other. Finally, the most comfortable materials and fabrication processes can select based on these results. The results show the changes in the static behavior of three laminate lay-ups at different test temperatures. At low temperatures, the static strengths are higher than the ones at room temperature.