• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.231-241
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• 2015

The direct strength method (DSM) has been adopted by the NAS (2004) and AS/NZS 4600 (2005) for the design of cold-formed steel members. The method can be successfully applied to the design of welded steel members. This paper reviews the development of the DSM for welded steel structural members. The design strength formulae for welded section columns and beams for the DSM are based on the test results performed on welded H-section, C-section, circular and rectangular hollow section columns, plate girders and stiffened plates. The comparison between the design strength of welded sections predicted by the DSM and that estimated by existing specifications is also provided. The comparison verifies that the DSM can properly predict the compressive, flexural and shear strength of welded section columns and beams with the interaction between local and overall buckling.

• Earthquakes and Structures
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• v.20 no.4
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• pp.431-444
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• 2021

T-shaped column is usually used as side column in buildings, which is one of the weak members in structural system. This paper presented a quasi-static cyclic loading experiment of six specimens of reinforced concrete (RC) T-shaped columns under compression-flexure-shear-torsion combined loadings to investigate the effect in the ratio of torsion to moment (T/M) and axial compression ratio (n) and height-thickness ratio of flange plate (φ) on their seismic performance. Based on the test results, the failure characteristics, hysteretic curves, ductility, energy dissipation, stiffness degradation and strength degradation were analyzed. The results show that the failure characteristics of RC T-shaped columns mainly depend on the ratio of torsion to moment, which can be divided into bending failure, bending-torsion failure and shear-torsion failure. With the increase of T/M ratio, the torsion ductility coefficient increased, and in a suitable range, the torsion and horizontal displacement ductility coefficient of RC T-shaped columns could be effectively improved with the increase of axial compression ratio and the decrease of height-thickness ratio of flange plate. Besides, the energy dissipation capacity of the specimens mainly depended on the bending and shear energy dissipation capacity. On the other hand, the increase of axial compression ratio and the ratio of torsion to moment could accelerate the torsional and bending stiffness degradation of RC T-shaped columns. Moreover, the degradation coefficient of torsion strength was between 0.80 and 0.98, and that of bending strength was between 0.75 and 1.00.

• Structural Engineering and Mechanics
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• v.22 no.3
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• pp.311-330
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• 2006

Standard compression tests of steel fiber reinforced concrete (SFRC) cylinders are conducted to formulate compressive stress versus compressive strain relationship of SFRC. Axial pullout tests of SFRC specimens are also conducted to explore its tensile stress strain relationship. Cover concrete spalling and reinforcement buckling models developed originally for normal reinforced concrete are modified to extend their application to SFRC. Thus obtained monotonic material models of concrete and reinforcing bars in SFRC members are combined with unloading/reloading loops used in the cyclic models of concrete and reinforcing bars in normal reinforced concrete. The resulting path-dependent cyclic material models are then incorporated in a finite-element based fiber analysis program. The applicability of these models at member level is verified by simulating cyclic lateral loading tests of SFRC columns under constant axial compression. The analysis using the proposed SFRC models yield results that are much closer to the experimental results than the analytical results obtained using the normal reinforced concrete models are.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.593-600
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• 1998

In this study, confinement stress of concrete compression members rehabilitated with C.F.L were analyzed from the test. Test parameters are spacing, thickness and ply of rehabilitation material. Displacement, failure load were measured during test. The failure mode and ultimate load were analyzed from these measured data. In this study, a model equation for calculation of the confining stress with C.F.L was proposed based on the test results investigated here. The proposed equation included the effects of spacing, thickness and ply of rehabilitation material.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.264-267
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• 2004

It is well known that axial tension decreases the shear strength of RC beams without transverse reinforcement, and axial compression increases the shear resistance. What is perhaps not very well understood is how much the shear capacity is influenced by axial load. RC beams without shear reinforcement subjected to large axial compression and shear may fail in a very brittle manner at the instance of first diagonal cracking. As a result, a conservative approach should be used for such members. According to the ACI Code, the concrete contribution is calculated by effect of axial force and the vertical force in the stirrups calculated by $45^{\circ}$ truss model. This study was performed to examine the effect of axial force in reinforced concrete beams.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.143-148
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• 2000

This paper describes how to make tailored blanks of front side member that were composed of high strength steel and TRIP(TRansformation Induced Plasticity) steel for weight reduction and improvement of crash load. Tailored blanks made by laser and mash-seam welding were compared with non-tailored blanks made by spot welding. Static compression tests were performed for performance comparison of each sample. Front side members made by tailored blank were superior to those made by spot welding in the initial, but those results were inverse in the last. Average load of tailored blank in six-angle type was better than that of rectangular type.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.200-205
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• 2001

This paper describes how to make tailored blanks of front side member that were composed of high strength steel and TRIP(TRansformation Induced Plasticity) steel for weight reduction and improvement of crash load. Tailored blanks made by laser and mash-seam welding were compared with non-tailored blanks made by spot welding. Static compression tests were performed for performance comparison of each sample. Front side members made by tailored blank were superior to those made by spot welding in the initial, but those results were inverse in the last. Average load of tailored blank in six-angle type was better than that of rectangular type.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.349-352
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• 2006

Pull-off test is generally used as a method of evaluating bond strength of FRP with concrete at the job site. However, pull-off test damages FRP composites and the maximum pull-off strength is limited up to tensile strength of concrete. Accordingly, it is required to set-up a test method that can simply evaluate bond performance of structural adhesive. This study suggested compression and bending test of epoxy resin as test methods that can indirectly evaluate performance of adhesive, as well as standardized test specification for different types of specifications from various countries. In this study, the section dimension of compression and bending test specimens is unified, and standard test specimen size is achieved by test results.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.371-376
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• 1998

In this study, the size effect of concrete members subjected to the axial load and bending moment is investigated using a series of C-shaped specimens of which test procedure is similar to those of Hognestad, Hanson, and McHenry's. Main test variable is a size ratio of the specimens(1:1/2:1/4) at the concrete compressive strength of 500kg/㎠. Test results show that the flexural compression strength at failure decreases as the size of specimen increases, that is, the size effect law is present. Model equation is derived using regression analyses with experimental data and it is compared with formulas for compressive strength of cylinders and shear strength of beams without stirrups. Size effects is distinct th following sequence; shear strength of beams without stirrups, compressive strength of C-shaped specimens, compressive strength of cylinders.