• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.61-68
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• 2007

The hole for the insertion of the pin in the shank is exist at ball joint connection of the space frame. It brings about the brittle fracture caused by stress concentration. Consequently it cannot expect the deformation performance or energy absorption performance from ball joint connection. In this study we developed a new connection details which will increase the plastic deformation performance at ball joint connection and can absorb the error in construction, which expect the plastic deformation performance at the reduced shank without brittle fracture at the screw of bolt and pin. Also it's capacity is verified by the performance in numerical analysis and test. We confirmed bolt's plastic deformantion performance through controled shank and pin's area.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.829-838
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• 2008

In this study, cyclic tests of beam-column connections composed with members applicable to the domestic low-middle rise steel buildings were conducted to develop seismic connection details and its evaluation. Connection types and material properties of the steel were testing variables and the difference between the newly developed seismic rolled section (SHN490) and existing rolled section (SM490) was also investigated. Distributions of the yield strength and the ultimate strength of the SHN490 rolled section were relatively uniform comparing to those of the SM490 rolled section Brittle fracture in the weldments of the test specimens was not observed. Instead, fracture occurred at heat-affected zones or the stress-concentrated point near the weld access hole of the beam flanges. In the case of identical rolled-section specimens, the rotational capacity and dissipated energy of the WUF-W connection was larger than those of the WUF-B connection. In the case of identical connection types, the rotational capacity and dissipated energy of the SHN490 section connection was larger than those of the WUF-B section connection.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.265-273
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• 2007

The most common structural system for apartment buildings in Korea is adopted to combine structural systems: for example, a moment-resisting frame will be used for lower stories and bearing wall system for the upper stories. This type of buildings have soft and/or weak stories in lower stories, and it may lead to collapse of those buildings during the large earthquake. Reversed cyclic load tests were conducted to estimate the performance and behavioral characteristics of deep beam and exterior column Joints. Experimental parameter is the amount of transverse reinforcement (designed by ACI code and Sheikh's procedure). The results of this study are as follows: (1) The required transverse reinforcement of column designed by Sheikh's procedure requires 2.9 times larger than that designed by ACI procedure. Large amount of transverse reinforcement increase the ductility of the column. (2) Most of the lateral drift in the column is due to the flexural deformation in the joint and plastic hinge region and up-lift rotation. (3) Transverse reinforcement in the exterior column shall be required not only in the hinge region but also in the joint.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.83-91
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• 2021

In this study, to improve the connection performance between the existing reinforced concrete (R/C) frame and the strengthening member, we proposed a new H-section steel frame with elastic pad (HSFEP) system for seismic rehabilitation of existing medium-to-low-rise reinforced concrete (R/C) buildings. This HSFEP strengthening system exhibits an excellent connection performance because an elastic pad is installed between the existing structure and reinforcing frame. The method shows a strength design approach implemented via retrofitting, to easily increase the ultimate lateral load capacity of R/C buildings lacking seismic data, which exhibit shear failure mechanism. Two full-size two-story R/C frame specimens were designed based on an existing R/C building in Korea lacking seismic data, and then strengthened using the HSFEP system; thus, one control specimen and one specimen strengthened with the HSFEP system were used. Pseudodynamic tests were conducted to verify the effects of seismic retrofitting, and the earthquake response behavior with use of the proposed method, in terms of the maximum response strength, response displacement, and degree of earthquake damage compared with the control R/C frame. Test results revealed that the proposed HSFEP strengthening method, internally applied to the R/C frame, effectively increased the lateral ultimate strength, resulting in reduced response displacement of R/C structures under large scale earthquake conditions.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.689-697
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• 2005

Recent test results on reduced beam section (RBS) steel moment connections show that specimens with a bolted web connection tend to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. A review of previous test results indicates that the higher incidence of base metal fracture in bolted-web specimens is related, at least in part, to the web bolt slippage and the high stress concentration at the weld access hole with the lowest material toughness. The practice of providing web bolts uniformly along the beam depth based on the classical beam theory is questioned in this paper. A new seismic design procedure, which is more consistent with the actual load path identified from the analytical and experimental studies, is proposed together with improved connection details. A test specimen designed following the proposed procedure exhibited a cyclic connection rotation capacity sufficient for special moment frames without fracture.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.355-363
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• 2010

The objective of this study is to examine the structural performance on the Rectangular Steel Tube Column-to-H Beam connections using one-side bolts and T-stub. Although a rectangular steel tube comparing with a H-shaped steel has many advantages and is more efficient, its application is limited due to the lack of experiences and connection details. Existing steel moment connections using the rectangular steel tube are mainly using through plate diaphragms. Its processing of construction is so complicated that it is hard to apply in the field. In this study, the structural performance and the earthquake capacity for T-stub connection with one-side bolts were investigated. And it is performed a comparative analysis of strength, rigidity, total rotation and energy absorption capacity for the various connection details.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.691-700
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• 2008

Contemporary architectural structures have diverse and complex forms. Such structural variety demands requisite performance from the connections in the steel structure so that the latter could resist a horizontal force, such as an earthquake. The connections are the all-important components that create the discontinuous form and that support stress concentration, determining the stiffness and toughness of the entire steel frame. In this study, a real-scale column-to-beam connection was constructed in the 600MPa-grade high-strength and high-performance steel, to test its behavior. Its material and welding characteristics were examined in this study, and its structural performance was analyzed by conducting seismic-resistance tests on the full-scale, cross-shaped column-to-beam welded connections with non-scallop, ordinary-scallop, and reinforced-scallop details. The weld ability of the high-strength, high-performance steel was also evaluated, and data regarding the seismic design for practical application were provided.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.262-269
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• 2021

This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.

• KIEAE Journal
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• v.7 no.6
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• pp.113-118
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• 2007

The composite beam adopted in the study was designed to reduce the floor height as well as to embed the top flange of steel frame into the slab that will enable to avoid applying the fire-resistant coating and to unify the joint method with a steel frame-type. As the steel frame and bottom concrete of the beam is pre-fabricated at the factory it could reduce the overall schedule at the jobsite. Applying such composite beam system to the work is expected to provide the efficient and enhanced performance, given the current tendency of the building construction that tends to be getting higher, larger and dense. The study focused on combining the composite beam with various column systems in a bid to propose the details thereof. A desirable composite girder can be adopted depending on site conditions through the evaluation of various beam and jointing approaches. Among the column systems applied to the study are steel column, SRC column, RC-PC column and RC column. The ways of combining with the columns addressed in the study were categorized into the rigid joint, pin joint, steel frame joint and bracket type joint. Besides, the instruction for site fabrication of beam-column was added in an effort to help set up the site fabrication procedures.

• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.325-335
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• 2005

This study tackles the development of an improved detail of partially restrained CFT square column-to-beam connection and the evaluation of its mechanical behavior under monotonic loading. The connection is designed to strengthen shearing capacity at the bottom of the connection due to the ultimate behavior of PR-CC by its detail of the bottom connection and simplify the fabrication process. The suggested connection is the welded bottom beam flange connection(M-2) and is compared with the existing PR-CC of bolted seat angle connection(M-1). Two specimens were fabricated in actual size and tested under monotonic loading. Based on the test results, the welded bottom beam flange connection exhibited about 85% of the stiffness of steel beam. It was similar to the bolted seat angle connection and behaved as PR-CC. The specimen of the supposed connection type failed at the shear connection of web but was similar to the bolted seat angle connection until the failure. It obtained sufficient stiffness and capacity through the reinforcingsteel and the capacity and deformational ability equivalent to the full-plastic moment through the anchor inside the steel tube at the web connection. So, it can be said that the suggested connection exhibits sufficient ductile behavior.