• Proceedings of the KWS Conference
• /
• 2007.11a
• /
• pp.53-56
• /
• 2007

Magnesium sheet used in electrical device due to mobility and EMF shielding characteristics. Magnesium case by press forming was advantageous compare with conventional die casting process, because of its thin gauge of wall and surface quality. But it need to makes the boss to fix inner part or assemble the case. CD stud welding was effective way for joining the boss to the thin gauge case of the electrical devices. In this study, we investigated the performances of the magnesium boss welder To measure the process parameters such as the force and the weld current, we design the monitoring system for CD stud welding. We test the characteristics of CD stud welding for AZ31 sheets at some variables. Finally we select the optimum welding range of magnesium sheets in CD stud welding process.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.3
• /
• pp.739-746
• /
• 2014

The objective of this test series was to determine shear load per unit length which causes a unit slip in the fastener joint. The shear load is one of major factors which reflect partial composite action for cold-formed steel wall stud panels. Test method used were based on the methods presented in the 1962 AISI Specification. According to the comparison with experimental strength, it is seen that the shear loads used in nominal axial strength predictions made acceptable results.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.3
• /
• pp.107-114
• /
• 2014

Modular systems are widely used in various building types including housing, dormitory, and barracks. Steel studs have many advantages over other materials as construction components of modular buildings in terms of seismic performance, durability and maintenance. However, steel stud modular systems also have weakness in condensation resistance due to high thermal conductivity of steel. The purpose of this study is to investigate the condensation resistance of steel stud wall corner details in modular buildings by thermal simulation. The condensation resistance was evaluated by temperature difference ratio according to ISO 13788. The result showed that there was little difference between the alternatives of adding cavity and insulation. Separation of interstitial steel studs showed outstanding effect on the improvement of temperature difference ratio.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.4
• /
• pp.66-76
• /
• 2008

Recently, demands for the structural uses with domestic Japanese larch and SPF(spruce-pine-fir) lumber from North America have been increased. Shear properties of nailed joints that are the most simple and optimum fastening method in wooden constructions, especially in light frame construction. For the nailed joints, in North America and Japan, a number of basic and practical studies have been performed. The shear behaviors for the double nailed joint with variations of member and its direction, were examined. Shear properties of the shear specimens with SPF stud showed more remarkable variation than larch glulam and larch stud. Furthermore, the relationships between slip modulus and strength are not coincided in every case.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.6
• /
• pp.515-527
• /
• 2013

Building energy simulations which are mainly used in Korea have evaluated the building energy performance with the different thermal conductivity of construction materials. In order to evaluate the energy consumption accurately, the difference in thermal conductivity of the wood used in stud for wooden structure was confirmed from the each simulation. In addition, the thermal transmission of building members and the thermal bridge at the conjunction of building members according to thermal conductivity from each simulation programs were researched. The thermal conductivity of pine that has the largest variation among the energy simulations was applied to the thermal properties of studs in wooden structure. The maximum error between the maximum and minimum thermal transmission of roof, wall, and floor slab was $0.023W/m^2{\cdot}K$. Plus, that thermal bridge at Rafter junction on the roof, roof-wall joint, and floor slab-wall joint was $0.025W/m{\cdot}K$. The heat transfer image for changes in temperature and the heat exchange were analyzed by HEAT2 program. The distorted temperature lines were found around the insufficient insulated connection parts. It was predicted that the temperature at the distorted parts in the analyzed image was lower than that of the other portion of the other structures.

• Journal of the Korea Concrete Institute
• /
• v.17 no.2 s.86
• /
• pp.191-200
• /
• 2005

Flat plate-column connections are susceptible to brittle punching shear failure, which may result in collapse of the overall structure. In the present study, a new shear reinforcement for the plate-column connection, the lattice shear reinforcement was developed. Experimental study for the lattice shear reinforcement was performed. Shear strength and ductility of the specimens reinforced with the lattice bars were compared with those of unreinforced specimens. The test results showed that the strength and ductility of the specimens with the lattice shear reinforcement were improved by 1.37 and 9.16 times those of the unreinforced specimens, respectively. These results indicates that the lattice shear reinforcement is superior in ductility to the shear stud-rail which is popular in U.S. Based on the test results, the design method for the lattice shear reinforcement was developed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1A
• /
• pp.89-94
• /
• 2008

The problem of interaction between the structures interconnected at discrete points as like composite structures, has a attracted considerable attention for a prolonged period of time. Recently, mixed structures are applied for overcoming structural limits by developed countries. In this paper, advanced connection type of mixed structures are presented by numerical approach. Also it is performed on extensive literature review from theoretical method to numerical analysis. For analysing behaviors of mixed structures according to connection type, 2 different connections and 1 reinforced connection are compared by 3D nonlinear numerical analysis. Nonlinear analysis of mixed structures is carried out by utilizing contact elements of a general purpose structural analysis computer program(ABAQUS). By using 6 criteria, each connections are investigated. From this result, proper reinforcing and well designed connection type are proposed. And results also show that the deflections which are induced by discontinuity on mixed structures, has a linear distribution that should decrease as applying proposed connection type.

• Journal of Korean Society of Steel Construction
• /
• v.29 no.1
• /
• pp.25-36
• /
• 2017

In the 1994 Northridge earthquake, connection damage initiated from the beam bottom flange was prevalent. The presence of a concrete slab and resulting composite action was speculated as one of the critical causes of the prevalent bottom flange fracture. In this study, four seismic retrofit schemes are proposed in order to salvage welded steel moment connections with composite floor slabs in existing steel moment frames. Because top flange modification of existing beams is not feasible due to the presence of a concrete floor slab, three schemes of bottom flange modification by using welded triangular or straight haunches or RBS(reduced beam section), and beam web strengthening by attaching heavy shear tab were cyclically tested and analyzed. Test results of this study show that haunch and web-strengthened specimens can eliminate the detrimental effect caused by composite action and ensure excellent connection plastic rotation exceeding 5% rad. Design recommendations for each retrofit scheme together with supplemental numerical studies are also presented.

• Journal of the Korea Institute of Building Construction
• /
• v.13 no.5
• /
• pp.482-490
• /
• 2013

Although the flat plate system is an efficient structural type due to the simplicity of its construction, the low story height, and the various plan design, the slab-column connections are vulnerable to punching shear failure from gravity load and eccentric shear failure from lateral load. To prevent the structure collapse, various construction methods of slab-column connection reinforcement are developed but none of these satisfies all of structural performance, economics, and constructability. This paper presents the reinforcement of slab-column connection with lattice bars. The structural performance is confirmed with the interior slab-column connection tests subjected to cyclic loading, and the economic feasibility is demonstrated from the structural design under the same condition with lattice bars, stud rails, and stirrups.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.3
• /
• pp.337-347
• /
• 2011

In this study, seismic resistance of concrete encased U-shaped steel beam-to-steel H-shaped column connections was evaluated. Three specimens of the beam-to-column connection were tested under cyclic loading. The composite beam was integrated with concrete slab using studs. Re-bars for negative moment were placed in the slab. The primary test parameter was the details of the connections, which are strengthening and weakening strategies for the beam end and the degree of composite action. The depth of the composite beams was 600mm including the slab thickness. The steel beam and the re-bars in the slab were weld-connected to the steel column. For the strengthening strategy, cover plates were weld-connected to the bottom and top flanges of the steel beam. For the weakening strategy, a void using styrofoam box was located inside the core concrete at the potential plastic hinge zone. The test results showed that the fully composite specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity of the beam exceeded 4% rotation angle, which is the requirement for the Special Moment Frame.