• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.335-348
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• 2014

For high-strength steel, it is difficult to be applied to flexible structural member because it have high yield ratio and low basic material's toughness. One of the great problems when using high-strength steel connections is the brittle fracture at the end of the beam member in common with general mild steel connections. In the cases of mild steel connections, it has be developed that special moment frame connection details by reinforcing structural member or improvement of welding access hole. But, it is incomplete at yet about applicability estimation of high-strength steel connections. This study is the initial step research for the applicability estimation of beam-to-column connections being applied to developed high-strength steel, HSA800. And, it studied about structural performance of the high-strength steel connections according to the details of welding access hole through full-scale test and analytical method.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.487-494
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• 2000

This paper intends to propose design information with the result or comparing the deformation capacity with different panel stiffness specimens and estimating the plastic deformation capacity, toughness and strength of welded joint connection according to the different scallop types. The test results of the beam to column unit structure are as follow: the non-scalloped and the low stiffness panel specimen have more desirable result values than the scalloped and the high stiffness one in plastic deformation. Comparing the scallop types shows very unlikely tendency as follows, second cracking occurs at the very edge of scallop in the scalloped specimen otherwise cracking occurs bond area of welded beam flange in the non-scalloped one.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.375-384
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• 2009

The application of the diagrid structural system has increased of late, but cyclic loadings such as winds and earthquakes cannot be fully understood through only an analytical study due to the difficulty of considering its welding property. In this study, diagrid nodes that had been scaled down to 1/5 of their full sizes were tested to find out their structural behavior under seismic or wind loads. Four specimens were used with five parameters, including the welding method and the design details. Cyclic loading tests were carried out, where a tensile load was applied to one brace member and a compression load to the other. The major failure modes in the tests were only failure of bending with tensile stress and tension failure. The welding method and the design details had no effect on the initial stiffness and yielding stress but play a significant role in the failure mode and energy dissipation, respectively.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.709-720
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• 1998

In order to study the distribution of welding residual stress through the plate thickness. experiment and analysis of fillet welding details were carried out. Especially, a residual stress in the weld root part of T-joint fillet weld whose measurement was difficult up to now was measured. By using the heat input and the number of the weld layers as parameters, the distribution of the 3-dimensional residual stress was investigated. As a result, we can say that with increasing the heat input, the residual stress in the weld toe and weld root barely changes. But, the area of the tensile residual stress became wide. Then, comparing a single pass with multi-pass weld method, it was found that the residual stress decreased more in multi-pass than in single pass. Moreover, it was found the thing that the area of tensile residual stress by multi-pass is lower than that by single-pass in the near weld part.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.23-32
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• 2006

This study was conducted to improve the design and construction technique of orthotropic steel-deck bridges. After conducting an F.E.M. analysis of the various rib types of the connection details, static and fatigue tests were conducted, using a three-dimensional, full-scaled, orthotropic, steel-deck-plate model with internal diaphrams, to check the fatigue strength depending on the types of details. The model structure was made of two types of longitudinal ribs: the domestic standard and the European rabbit types. The fatigue strength of the steel-deck system was found to have improved through the installation of an internal diaphram, as no cracks were found on the bottom round part of the scallop with a diaphram. There were no differences between the domestic and the European types of details in terms of strength may be partially influenced by the shape of the scallop and by the installation of an internal diaphram, but it can be improved more significantly according to the quality of the welding that will be done.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.629-637
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• 2003

This s paper presented the results of the three phases of fatigue tests to determine the fatigue strength of in-plane welded gusset joints, which are the most common details inevitably existing in the region of high stress range. A total of 57 fatigue specimens with varying thickness and strengths were made and tensile fatigue tests performed. One full-scale beam fatigue test was also performed. The validity of the fatigue strength of those details in the specification was confirmed, with the effects of thickness of flanges and welded attachments, length of attachments, and strength of applied steel examined. The characteristics of crack initiation and propagation were also observed. The test result was evaluated by comparing it with other test data and fatigue criteria of other countries. To determine the degree of stress concentration in the weld toe depending on geometric configuration such as attachment length and transition radius, analyses were performed. Compared to the present specification, analytical results indicate the need to revise and subdivide the detail categories.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.67-78
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• 2007

In this study, we performed an investigation on the variations in the structural capacity of steel plate walls with various infill plate details. Five three-story plate walls with thin web plates were tested. Parameters for the test specimens were the connection details between the moment frame and infill plates, such as weld and bolt connections, the location and length of weld connection, and coupling wall. Regardless of the details of infilled steel plate, the steel plate wall specimens showed excellent initial stiffness, strength, and energy dissipation capacity. However, the wall with bolt-connected infill plates showed slightly low deformation capacity. This result showed that for workability and cost efficiency,various wall details can be used in practice without causing a significant decrease in the structural capacity of steel plate walls. A method for making projections on strength and energy dissipation capacity of steel plate wall specimens with various details was developed.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.407-418
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• 2014

As a continuing work of previously conducted standard tension tests, full-scale flexural tests were conducted in this study to assess the structural performance the CJP groove welded joints connecting thick HSA800 plates. Two welding electrodes were available at the time of this experimental research; one was GMAW-based electrode A and the other FCAW-based electrode B. Three full-scale box-type beam specimens with single bevel- and V-groove CJP welded joints were fabricated from 60mm and 25mm thick HSA800 plates according to the AWS-prequalified groove welded joint details. In designing the specimens, all possible limit states like local and lateral torsional buckling were carefully controlled in order to induce flexural plastic yielding or eventual joint fracture. All the CJP joints made by both welding electrodes showed satisfactory performance and were able to transfer the tensile flange forces higher than that corresponding to the measured tensile strength of HSA800 flange plates. However, it should be noted that, during fabrication, serious concerns about the welding efficiency and workability of the GMAW-based electrode were raised by a certified welder. The fracture occurred at the unbeveled (or vertical) interface between the weldment and the base metal when the GMAW-based electrode was used in the single-bevel joint, implying the possibility of insufficient melting. Thus, the FCAW-based electrode B is again recommended as the choice of welding electrode for HSA800 plates. The limited test data of this study implies that the V-groove CJP joint should be used in favor of the single bevel CJP joint, if possible.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.451-461
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• 2013

In steel bridges, there are several details that constrain the deformation such as buckling by external forces. Most of these details which are composed of the intersection members have scallops in order to exclude the weld defects inherently and to get the ease of fabrication and also to decrease the stress concentration. In this study, stress relief hole (SRH) near stress concentration zone with detail category D or under is proposed as a method to improve the resistance on the fatigue crack initiation to detail category C. And the effects of the appropriate size and location of SRH were examined and the applicability to improve the fatigue resistance of the floorbeam web and the rib wall at rib/floorbeam intersection in the orthotropic steel deck bridge was evaluated.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.101-108
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• 2012

The orthotropic steel deck bridge made by using relatively thin steel plate, and structural members such as transverse and longitudinal ribs, cross beam, etc. in the bridge are fabricated with complex shape by welding. Therefore, the possibility occurring deformation and defects by welding is very high, and stress states in the welded connection parts are very complex. Also, the fatigue cracks in orthotropic steel deck bridge are happening fromthe welded connection parts of secondary member than main member. However, stress evaluation for main members is mainly carried out in the design process of the bridge, detailed stress evaluation and characteristic analysis is not almost reviewed in the structural details which fatigue crack occurred. For the orthotropic steel deck bridge with open ribs which has been serviced for 29 years, in this study, the cause of fatigue crack is investigated and the fatigue safety of the bridge is examined based on fieldmeasurement by the loading test and real traffic condition. Also, structural analyses using gridmodel and detailed analysis model were carried out for the welded connection parts of longitudinal rib and diaphramthat fatigue crack occurred. Additionally, the behavior characteristics due to running vehicles were investigated by using influence area analysis for these structural details, and the occurrence causes of fatigue crack in the target bridge were clarified.