• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.43-49
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• 2004

With building structures becoming higher and having longer spans, new structural steel with better strength, thicker plate, and performance may be required rather than conventional structural steel. TMC steel is widely used in building structures largely due to its excellent seismic performance, superior weldability, and design strength that is not affected by plate thickness. To make use of TMC steel in pipe structures with large diameter and heavy wall, however, the this study, the degradation of material properties in submerged are welded SM520TMC steel pipes and tubes was evaluated using variable fabrication process and material change. Degradation test results showed that the yield and ultimate strength increased and elongation decreased regardless of the mode of fabrication, i.e., through roll bending or press forming, or steel used, i.e., domestic SM520TMC steel or SM520TMC steel from Japan.

• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.847-855
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• 2004

The criterion or specification on fatigue design has been generally based on fatigue strength curve derived by tests on specimens with varying thickness (10-30mm). Making the plate thicker, however, also decreases fatigue strength. It has been noted from the test results and the results of the analysis by fracture mechanics that the effect of thickness cannot be bypassed. From the several fatigue strength curves of specimen tests, modification of fatigue strength on plate thickness has been proposed. In this study, fatigue tests on SM520C-TMC were carried out, and the effects of thickness were evaluated. Finally, in consideration of the thickness, the modification of fatigue strength was derived. Comparing the results of this paper with those of previous studies, an outline of the behavior obtained is similar to previous ones, but the rate of decrease is smaller.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.4 s.15
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• pp.1-6
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• 2004

Fatigue tests were carried out for butt welded joints with SM520-TMC steel plate with thickness between 20mm and 80mm. The test results were analysed statistically and the effect of plate thickness on the fatigue strength investigated. The fatigue strengths based on nominal stress range satisfy the requirement of the standards. Due to misalignment of the specimens, the measured stresses are higher than the nominal stresses especially for 20mm thick plates. If fatigue strengths are evaluated based on the measured stresses, then the fatigue strengths are greater than those based on nominal stresses. The results show that the thickness effect is similar to the formula proposed by Gurney.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.123-131
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• 2001

The objective of this study is to investigate the criteria of the width-to-thickness ratio and to evaluate the buckling strength of high strength steel beam-columns and to compare their buckling strength with design codes, which are the Limit State Design code and the Allowable Stress Desogn code(drift). SM520TMC and SM570Q class steels are used for high strength steels. The coupon test and the stub column test were carried out to investigate the properties of high strength steels and the stress-strain curves of stub columns. The buckling strength of high strength steel beam-columns are assessed by numerical analysis used axial force, moment and curvature relationships.

• Steel and Composite Structures
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• v.9 no.6
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• pp.557-568
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• 2009

Fatigue tests for extremely thick plates require a great deal of manufacturing time and are expensive to perform. Therefore, if predictions could be made through simulation models such as an artificial neural network (ANN), manufacturing time and costs could be greatly reduced. In order to verify the effects of fatigue strength depending on the various factors in SM520C-TMC steels, this study constructed an ANN and conducted the learning process using the parameters of calculated stress concentration factor, thickness and input heat energy, etc. The results showed that the ANN could be applied to the prediction of fatigue life.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.389-398
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• 2010

The flexural strength of composite HSB I-girders under a positive moment was investigated using the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specifications to such girders. A total of 2,391 composite I-girder sections that satisfied the section proportion limits of the AASHTO LRFD specifications was generated by the random sampling technique to consider a wide range of section properties. The flexural capacities of the sections were calculated inthe nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels were modeled as an elasto-plastic strain-hardening material, and the concrete, as a CEB-FIP model. The effects of the ductility ratio and the compressive strength of the concrete slab on the flexural strength of the composite girders made of HSB and SM520-TMC steels were analyzed. The numerical results indicated that the current AASHTO LRFD equation can be used to calculate the flexural strength of composite girders made of HSB600 steel. In contrast, the current AASHTO LRFD equation was found to be non-conservative in its prediction of the flexural strength of composite HSB800 girders. Based on the numerical results of this study for 2,391 girders, a new design equation for the flexural strength of composite HSB800 girders in a positive moment was proposed.