• Steel and Composite Structures
• /
• v.29 no.6
• /
• pp.717-734
• /
• 2018

This paper presents the flexural performance of steel beam-to-column joints composed of hollow structural section beams and columns. A finite element (FE) model was developed incorporating geometrical and material nonlinearities to evaluate the behaviour of joints subjected to bending moments. The numerical outcomes were validated with experimental results and compared with EN1993-1-8. The demountability of the structure was discussed based on the tested specimen. A parametric analysis was carried out to investigate the effects of steel yield strength, end-plate thickness, beam thickness, column wall thickness, bolt diameter, number of bolts and location. Consequently, an analytical model was derived based on the component method to predict the moment-rotation relationships for the sub-assemblies with extended end-plates. The accuracy of the proposed model was calibrated by the experimental and numerical results. It is found that the FE model is fairly reliable to predict the initial stiffness and moment capacity of the joints, while EN1993-1-8 overestimates the initial stiffness extensively. The beam-to-column joints are shown to be demountable and reusable with a moment up to 53% of the ultimate moment capacity. The end-plate thickness and column wall thickness have a significant influence on the joint behaviour, and the layout of double bolt-rows in tension is recommended for joints with extended end-plates. The derived analytical model is capable of predicting the moment-rotation relationship of the structure.

• The Korean Journal of Pain
• /
• v.20 no.1
• /
• pp.31-39
• /
• 2007

Background: Cervical radicular pain can arise fromvarious structures, including spinal nerves, discs, zygapophyseal joints, ligaments, and myofascial connective tissue. However, no adequate experiments have been found regarding methods for the microadhesiolysis of adhesional connective tissue around the zygapophyseal joints and nerves. The first objective of this study was to ascertain the effect of fluoroscopy guided interventional microadhesiolysis and nerve stimulation (FIMS) on chronic cervical radicular pain caused by zygapophyseal joint dysfunction. The second objective was to identify the duration of pain alleviation, as well as commonly occurring regions for zygapophyseal joint dysfunction. Methods: Twenty-eight patients were diagnosed with cervical radicular pain. The cervical zygapophyseal joints and adhesional structures around the cervical zygapophyseal joints were stimulated by adhesiolysis with a rounded needle; the procedure was performed once every second week. A visual analogue scale (VAS) for pain and neck range of motion (ROM) were used as indices for evaluating the degree of pain 1 and 3 months after completion of the procedures. A relief effect of FIMS was accepted when the VAS index decreased 50% compared with a previous VAS, and when there was absence of limitation of ROM. Results: Among the patients, 52% showed zygapophyseal joint dysfunction in C5-6, 38% in C4-5, 7% in C2-3, and 3% in C6-7. After performing FIMS, the VAS index decreased in most of the patients after 1 and 3 months (92.8% and 75%, respectively), and treatment frequency was $2.7{\pm}1.2$. There was no correlation between the number of FIMS procedures and the degree of VAS. Conclusions: FIMS is considered an effective modality in patients suffering from cervical radicular pain.

• The Journal of Korean Medicine
• /
• v.31 no.4
• /
• pp.63-78
• /
• 2010

Objectives: This study was carried out to know the effects of Gwan-Jul-Bang-7 (hereafter referred to GJB-7) on the inhibition of arthritis induced by collagen on the mouse. Methods: To assess the effects of GJB-7 on mouse with arthritis induced by collagen II, we conducted several experiments such as analysis of cytotoxicity, hepatotoxicity, arthritis index, total cell number of draining lymph nodes and paw joints, value of immunocyte in PBMC (peripheral blood mononuclear cell), DLN (draining lymph node) and paw joint, measurement of cytokine and anti-collagen II, observation of the histological changes of joint. Results: 1. Cytotoxicity against HFC (human fibroblast cells) was not observed in any concentration and hepatotoxicity was not observed in the GJB-7 treated group. 2. The incidence of arthritis significantly decreased. 3. Total cell number of draining lymph nodes significantly increased and total cell number of paw joints significantly decreased. 4. The percentage of $CD8^+$ cells in PBMC (peripheral blood mononuclear cell) significantly increased. The percentage of $CD3^+/CD69^+$, and $CD3^+/CD49b^+$ cells in PBMC significantly decreased. 5. The percentage of $CD19^+,\;CD3^+$, and $CD4^+/CD25^+$ cells in DLN (draining lymph nodes) significantly increased. The percentage of $B220^+/CD23^+$ cells in DLN significantly decreased. 6. The percentage of $CD3^+,\;CD4^+$, and $CD11b^+/Gr-1^+$ cells in paw joints significantly decreased. 7. The production of TNF-$\alpha$, IL-6, and MCP-1 significantly decreased. 8. Anti-collagen II in serum significantly decreased. 9. With the hematoxylin and eosin stain, inflammation of joint decreased. Under Masson's trichrome stain, the cartilage destruction and synovial cell proliferation and the expression of collagen fibers decreased. Conclusions: Comparison of the results for this study showed that GJB-7 had immunomodulatory effects. So we expect that GJB-7 could be used as an effective drug for not only rheumatoid arthritis but also another auto-immune diseases.

• Magazine of the Korea Concrete Institute
• /
• v.8 no.4
• /
• pp.171-179
• /
• 1996

A proposal of the basic fbrm on the design of joint parts that can increase the shear strength by the useful joint shapes of each member is intended. The vertical joint parameters are the number of' shear key and a variety of' reinfbrcement details and the horizontal joint paramctcrs arc t,hc number of shear key and the direction of' shear f'orcc. 10 PC panel vortical joint arid 12 PC panel horizontal joint specimens were tested to investigate the effects of these parameters. Test results show that : 1. The ductility of the test specimen that has the horizontal reinforcing steels is larger than that does not have. 2. The maximum resisting force of round bar specimen is similar to that of strand wire specimen under the condition of fixed horizontal displacement.

• Korean Journal of Metals and Materials
• /
• v.47 no.4
• /
• pp.261-266
• /
• 2009

The mechanical and electrical properties of ball grid array (BGA) solder joints were measured, consisting of Sn-3.5Ag, with organic solderability preservative (OSP)-finished Cu pads and Electroless Nickel/Immersion Gold (ENIG) surface finishes. The mechanical properties were measured by die shear test. When ENIG PCB was upper joint and OSP PCB was lower joint, the highest shear force showed at the third reflow. When OSP PCB was upper joint and ENIG PCB was lower joint, the highest shear force showed at the forth reflow. For both joints, after the die shear results reached the highest shear force, shear force decreased as a function of increasing reflow number. Electrical property of the solder joint decreased with the function of increasing reflow number. The scanning electron microscope results show that the IMC thickness at the bonding interface gets thicker while the number of reflow increases.

• Earthquakes and Structures
• /
• v.15 no.5
• /
• pp.499-511
• /
• 2018

This paper aims to investigate the seismic performance of the prestressed steel strips retrofitted RC beam-column joints. Two series of joint specimens were conducted under compression load and reversed cyclic loading through quasi-static tests. Based on the test results, the seismic behavior of the strengthened joints specimens in terms of the failure modes, hysteresis response, bearing capacity, ductility, stiffness degradation, energy dissipation performance and damage level were focused. Moreover, the effects of the amount of the prestressed steel strips and the axial compression ratio on seismic performance of retrofitted specimens were analyzed. It was shown that the prestressed steel strips retrofitting method could significantly improve the seismic behavior of the RC joint because of the large confinement provided by prestressed steel strips in beam-column joints. The decrease of the spacing and the increase of the layer number of the prestressed steel strips could result in a better seismic performance of the retrofitted joint specimens. Moreover, increasing the axial compression ration could enhance the peak load, stiffness and the energy performance of the joint specimens. Furthermore, by comparison with the specimens reinforced with CFRP sheets, the specimens reinforced with prestressed steel strips was slightly better in seismic performance and cost-saving in material and labor. Therefore, this prestressed steel strips retrofitting method is quite helpful to enhance the seismic behavior of the RC beam-column joints with reducing the cost and engineering time.

• Journal of Korean Society of Steel Construction
• /
• v.27 no.1
• /
• pp.53-61
• /
• 2015

The tension type joint is a mechanically very efficient connection method, as it directly uses the load capacity of base metal or high tension bolt, the reduction of the number of drilling hole and fastening and the fatigue resistance. It is applied to the joint of girder and cross beam, horizontal joints of towers, beam to column joints, the secondary member joints of deck floor ends, and brackets. In this paper, static load tests for the T-type tension joint were conducted to investigate the structural behavior of the joint. The parameters were bolt diameter, flange thickness, and the reduction of clamping force of the joint. The failure modes and load capacity of joints and the effects of flange thickness, bolt diameter and clamping force were investigated.

• Steel and Composite Structures
• /
• v.28 no.3
• /
• pp.363-380
• /
• 2018

This paper presented an integral design procedure for demountable bolted composite frames with semi-rigid joints. Moment-rotation relationships of beam-to-column joints were predicted with analytical models aiming to provide accurate and reliable analytical solutions. Among this, initial stiffness of beam-to-column joints was derived on the basis of Timoshenko's plate theory, and moment capacity was derived in accordance with Eurocodes. The predictions were validated with relevant test results prior to further applications. Frame analysis was conducted by using Abaqus software with material and geometrical nonlinearity considered. Variable lateral loads incorporating wind actions and earthquake actions in accordance with Australian Standards were adopted to evaluate the flexural behaviour of the composite frames. Strength and serviceability limit state criteria were utilized to verify configurations of designed models. A wide range of frames with the varied number of storeys and bays were thereafter programmed to ascertain bending moment envelopes under various load combinations. The analytical results suggest that the proposed approach is capable of predicting the moment-rotation performance of the semi-rigid joints reasonably well. Outcomes of the frame analysis indicate that the load combination with dead loads and live loads only leads to maximum sagging and hogging moment magnitudes in beams. As for lateral loads, wind actions are more crucial to dominate the design of the demountable composite frames than earthquake actions. No hogging moment reversal is expected in the composite beams given that the frames are designed properly. The proposed analysis procedure is demonstrated to be a simple and efficient method, which can be applied into engineering practice.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.1
• /
• pp.141-152
• /
• 2002

Although a number of constitutive models have been proposed to define the behavior of geotechnical materials including elastic, plastic, and dynamic response, flew numerical models have been developed for the cyclic shear behavior of rock joints or interfaces. Such realistic constitutive models play an important role in analyzing and predicting the response of joints under dynamic loads. The purpose of this research is to verify the constitutive model modified for rough granite joints based on Disturbed State Concept(DSC) model, which has been successfully verified with respect to other materials such as dry sand-steel interface and wet sand-concrete interface. Furthermore, DSC model is compared and verified with respect to cyclic shear tests and numerical analysis results based on Plesha model. Based on the results of this research, it can be stated that DSC model is capable of characterizing the cyclic shear behavior of rough granite joints under dynamic loads.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.2A
• /
• pp.327-338
• /
• 2006

Friction type high tension bolted joints is one of the most common steel structure connections and requires significant concerns on axial force of the bolts. However, its high shear capacity is not appropriately considered in design and hence the number of bolts is over-designed than actually required. It is primarily due to a slip-load-based design method. This study, therefore, suggests a new technology of connection using a shear ring, which may reduce the shortcomings from the friction-typed high tension bolted joints and maximize the advantages from the bearing-typed joints. Experimental and numerical studies were performed to compare the capacity of the suggested method with traditional high tension bolted joints. From the results, it is known that the suggested connections has higher bearing capacity than friction-typed high tension bolted joints due to the higher shear resistance from the ring. For further study, it may be necessary to investigate on design parameters including the depth of shear ring, for increased connection capacity.