• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.3
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• pp.115-123
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• 2017

To investigate the cyclic characteristics of the retrofitted exterior joints of RC frame with haunch, 70% scaled 6 beam-column exterior joint subassemblies were designed according to design guideline according to 1988 and tested with cyclic loading up to 3.5% story drift ratio. During the experiments axial forces are applied to columns to simulate gravity load. Experimental results shows that the strength of retrofitted specimens was increased steadily until 2.5% story drift ratio and their strengths increased more than 1.7 times of the non-retrofitted in case that main bar was bent away from exterior joint. The joint strength and effective stiffness of the retrofitted specimen was increased and results in more deformation capacity compared to the non-retrofitted.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.95-102
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• 1996

In this study, a stochastic finite element model is proposed with a view to consider the uncertainty of physical properties of discontinuous rock mass in the analysis of structural behavior on underground caverns. In so doing, the LHS(Latin Hypercube sampling) technique has been applied to make up weak points of the Crude Monte Carlo technique. Concerning the effect of discontinuities, a joint finite element model is used that is known to be superior in explaining faults, cleavage, things of that nature. To reflect the uncertainty of material properties, the variables such as the the elastic modulus, the poisson's ratio, the joint shear stiffness, and the joint normal stiffness have been used, all of which can be applicable through normal distribution, log-normal distribution, and rectangulary uniform distribution. The validity of the newly developed computer program has been confirmed in terms of verification examples. And, the applicability of the program has been tested in terms of the analysis of the circular cavern in discontinuous rock mass.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.91-97
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• 1995

Cyclic tests were performed with dowel joints which are being widely used for furniture manufacturing in Korea. In this study, effects of various factors-such as species of joint members, diameter and length of dowels, and space between dowels-on stiffness, strength and damping ratio of joints were evaluated and concluded as follows: 1. Under cyclic loads, failure of dowel joints were caused by bending failure of dowels. 2. Dowel joints were evaluated to be stiff but general load carrying capacities were relatively low. 3. Joint moduli and damping ratios of dowel joints decreased as diameter and length of dowels, and space between dowels increased. 4. In dowel joints, properties of dowel itself have greater effects on stiffness and strength of joints than properties of joint members.

• Structural Engineering and Mechanics
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• v.87 no.2
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• pp.137-149
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• 2023

In this study, to explore the working performance of the CFST split spherical node wind power tower, two groups of CFST split spherical joint plane towers with different web wall thicknesses and a set of space systems were analyzed. The tower was subjected to a low-cycle repeated load test, and the hysteresis and skeleton curves were analyzed. ABAQUS finite element simulation was used for verification and comparison, and on this basis parameter expansion analysis was carried out. The results show that the failure mode of the wind power tower was divided into weld tear damage between belly bar, high strength bolt thread damage and belly rod flexion damage. In addition, increasing the wall thickness of the web member could render the hysteresis curve fuller. Finally, the bearing capacity of the separated spherical node wind power tower was high, but its plastic deformation ability was poor. The ultimate bearing capacity and ductility coefficient of the simulated specimens are positively correlated with web diameter ratio and web column stiffness ratio. When the diameter ratio of the web member was greater than 0.13, or the stiffness ratio γ of the web member to the column was greater than 0.022, the increase of the ultimate bearing capacity and ductility coefficient decreased significantly. In order to maximize the overall mechanical performance of the tower and improve its economy, it was suggested that the diameter ratio of the ventral rod be 0.11-0.13, while the stiffness ratio γ should be 0.02-0.022.

• Steel and Composite Structures
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• v.21 no.3
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• pp.661-677
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• 2016

The quasi static test of the steel reinforced concrete (SRC) bridge piers and rigid frame arch bridge structure with SRC piers was conducted in the laboratory, and the seismic performance of SRC piers was compared with that of reinforced concrete (RC) bridge piers. In the test, the failure process, the failure mechanism, hysteretic curves, skeleton curves, ductility coefficient, stiffness degradation curves and the energy dissipation curves were analyzed. According to the $M-{\Phi}$ relationship of fiber section, the three-wire type theoretical skeleton curve of the lateral force and the pier top displacement was proposed, and the theoretical skeleton curves are well consistent with the experimental curves. Based on the theoretical model, the effects of the concrete strength, axial compression ratio, slenderness ratio, reinforcement ratio, and the stiffness ratio of arch to pier on the skeleton curve were analyzed.

• Steel and Composite Structures
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• v.32 no.3
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• pp.337-346
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• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.326-333
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• 2016

This case study identified the effects of joint mobilization on knee pain, isokinetic strength, muscle tone, and muscle stiffness in an elite volleyball player with a knee injury. The subject had experienced cartilage defects of the left knee joint and underwent surgery to correct the condition. The patient complained of continuous pain in the left knee joint in daily life in addition to pain during exercise. The study was conducted from August 5 to 12, 2015 and joint mobilization was applied to the left knee joint for 15 minutes once a day for 8 days. Knee pain was measured using a visual analogue scale, and the concentric peak torque of the quadriceps and hamstring muscles was measured using an isokinetic muscular strength measurement device. The muscle tone and stiffness of the rectus femoris muscle, vastus medialis, and vastus lateralis on the injured side were measured using a myotonometer. All the measurements were conducted before and after the intervention. Joint mobilization was effective in reducing knee pain on the injured side, increasing the concentric peak torque of the quadriceps and hamstring muscles on both sides, and increasing the muscle stiffness of the quadriceps muscle on the injured side. Concentric peak torque of the quadriceps muscle on the injured side increased a great deal as the number of joint mobilizations was increased, largely diminishing the difference in concentric peak torque between the normal side and injured side. On the other hand, joint mobilization was ineffective in improving the hamstring to quadriceps strength ratio on the injured side. While this study suggests that joint mobilization can be an effective intervention to improve the knee pain, isokinetic strength, and muscle stiffness of elite volleyball players, it should be performed alongside training for an appropriate strength ratio.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.60-65
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• 2017

This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.227-234
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• 2003

This study presents the stress evaluation equations of circular column-box beam connection in steel frame piers. FEM analysis were carried out for circular column-box beam connection. Analysis models were made for design parameters such as joint angle, span length-width ratio(L/B), sectional-area ratio(S=A/sub w/A/sub f/), and circular column-box beam stiffness ratio(Ic/Ib). Analysis results were compared to the existing equation. Based on analysis results the stress evaluation equations of circular column-box beam connection are proposed by regression analysis.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2838-2843
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• 2011

Recently, the floating slab track that can effectively mitigate the vibration and structure-borne noise is being discussed to be adopted. The floating slab track which is a track system isolated from the sub-structure by vibration isolators. Unsimilarly to conventional track and the slab deflection is large. Therefore, the running safety and ride comfort should be investigated. Especially at slab joint since the load cannot be transferred, the possibility that the dynamic behavior of track and train became unstable is high. Thus, in general dowel bar are often installed at slab joints. To determine the appropriate dowel ratio the load transfer characteristics should be investigated. In this study, dowel bar joint is modeled by equivalent shear spring and this model is verified by comparison with experimental results. Using the proven model, the load transfer efficiency and deflection at slab joint according to dowel ratio, and stiffness and spacing of vibration isolator were examined.