• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.435-442
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• 2012

Recently, high performance(strength) steels have been utilized to structural materials in buildings and bridges with the demand for high-rise and long-span of main structures. This paper is a series of basic study for the design specification of structural members using high performance steel, material properties of high performance rolled steel building structures. HSA800 was compared with the requirements of Korean Standards(KS) for HSA800. Welded square tube stub columns with variables of width-to-thickness ratios are planned in order to investigate the local buckling behaviors and check the current design limit of width-to-thickness ratio and uniaxial compressive tests are carried out. In addition, the local buckling behaviors of stub columns obtained finite element analysis were compared with those of test results.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.595-602
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• 2007

Recently, concrete structures with carbon fiber reinforced polymer (CFRP) reinforcements have been commonly used for the bridge and building construction. In this paper, pier caps were strengthened by prestressed near surface mounted CFRP. To verify the effectiveness of the strengthening method, 7 pier cap specimens were fabricated. One specimen was designed for control, two for external prestressing steel strands, two for CFRP plates, and two for CFRP bars. Experimental variables consist of type of reinforcement materials and prestressing levels. The results of laboratory have shown that the ultimate load capacities of prestressed near surface mounted CFRP specimens were about $20{\sim}33%$ greater than that of a control specimen. Also, ultimate load capacities of prestressed near surface mounted CFRP specimens were similar to those of external prestressing specimens with steel strands.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.303-309
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• 2011

Laminated rubber bearing is the most commonly used device for seismic base isolation of bridge structures. It is important to know performance and behavior characteristics of the laminated rubber bearings. The main evaluation factors of the rubber bearing are classified as compressive, shear and tensile behavior characteristics. The reference data of compressive and shear characteristics are rich, but the reference data of tensile characteristics is scarce. In this study, tensile test results of the rubber bearing with variation of shape factor and shear deformation are investigated for mechanical property. When tensile deformation in normal condition is increasing, tensile cycle behavior curve becomes non-linear and tensile breaking point is 300%. On the other hand, tensile breaking point is shear deformation condition is about 40%. Furthermore, when shape factor is lower, tensile breaking point is decrease. This results mean that tensile breaking point is decreased in triaxial tensile deformation because of cracks caused by internal void of the rubber bearings. This experimental data can be used as the reference data of tensile characteristics for designing seismic isolation of structures.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.269-279
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• 2000

It is much expected that steel bridges, which have been damaged by increase of vehicle load and corrosion, need repair or strengthening. In this paper, the stress generated by repair welding under loading are analyzed by three dimensional elasto-plastic analyses. The longer and deeper repair weld line bocemes, the larger the magnitude of transient stress becomes. The magnitude of transient stress generated by repair welding under loading $({\sigma}_y/3,\;{\sigma}_a)$ is similar to summation of stresses generated by repair welding and loading. The longer repair weld line ratio(1/b) becomes, the larger the magnitude of transient stress generated by repair welding under loading bocomes. And, the longer repair weld line ratio(1/b) becomes, the larger the magnitude of in-plane displacement generated by repair welding under loading$({\sigma}_y/3,\;{\sigma}_a)$.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.289-299
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• 2006

Orthotropic steel decks are manufactured by welding thin plates therefore it is inevitable that there are abundant works of welding process. On connection of transverse rib web, crossing point of longitudinal rib, transverse rib and deck plate and cut-out parts of transverse rib are the significant position of stress concentration phenomenon because of out of plane and oil-caning deformation caused by longitudinal rib distortion with shear force and distortion. In order to reduce the stress concentration phenomenon and improving fatigue performance at the crosing point and cut-out, structural analysis was performed considering the existence of scalop at conection and diaphragm which have same plane with transverse rib placed inside of longitudinal rib. Result o f the analysis show that there are the largest efect of stres concentration reduction when diaphragms are installed without scallop at connection, therefore these detail can improve the fatigue performance of orthotropic steel decks.

• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.371-376
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• 2015

This study was conducted for the torsional behavior of catwalk system which is a temporary structure on a suspension bridge. The torsional deformation of the catwalk structure has a significant effect on the workability and safety of workers during main cable erection. For this reason, the torsional deformation of catwalk is controlled to be acceptable levels below by adjusting the cross bridge interval in design stage. This study analyzed the effect of separation between cross bridge associated with twist safety of catwalk system. For the analytical approach, a detailed analysis model was created including cross bridge. Both wind load within the wind velocity range that allows the construction and eccentric load of Prefabricated Parallel Wire Strand were analyzed by analysis model. Result of study shows that separation between cross bridges has a significant effect on the torsional behavior of the catwalk.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.627-636
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• 2012

Recently, high performance(strength) steels have been utilized to structural materials in buildings and bridges with the demand for high-rise and long-span of main structures. This paper is a series of basic study for the design specification of structural members using high performance steel, material properties of high performance rolled steel building structures; material properties of HSA800 steel was compared with the requirements of Korean Standards(KS) for HSA800. Welded H-shape stub columns with variables of width-to-thickness ratios are planned in order to investigate the local buckling behaviors and check the current design limit of width-to-thickness ratio and uniaxial compressive tests are carried out. In addition, the buckling behaviors of stub columns obtained finite element analysis were compared with those of test results.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.223-231
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• 2013

Recently, high-performance steels have been increasingly used for structural materials in buildings and bridges with the demand for high-rise and long-span of main structures. This paper offers a series of basic study for the design specification of structural members using high performance steel, that is material properties of HSA800 (High-performance rolled steel for building structures). Built-up square tube stub columns with variables of width-to-thickness ratios are planned as a parametric study in order to investigate the local buckling behaviors and check the current design limit of width-to-thickness ratio. In addition, the buckling behaviors of stub columns obtained finite element (FE) analysis were compared with those from experimental tests. The verified FE model was used for parametric study and checked applicability of high-strength steel on current design specification.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.16-22
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• 2012

The use of welding process has been increased for manufacture of machine, bridges, ships, gas facilities and so on together with development of welding technique. Accordingly, it has been needed to develop the welding methods considering higher productivity and safety design for manufacture of their welding structures. In this study, it was studied basically on characteristics of fatigue strength and fatigue life in full penetrated cruciform fillet weld zone in relation to material thickness, welding passes, loading direction and notch radius of toe zone. Most of fatigue failure occurred in toe zone of cruciform fillet weld joint. Fatigue strength and fatigue life are under the influence of stress concentration due to notch radius and flank angle of toe zone. The metal of toe zone annealed and diffused by multi-layer welding and acicular ferrite structure formed by the result improved fatigue strength and fatigue life.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.14-19
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• 2010

Theories for advanced composite structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The senior author has reported that some laminate orientations have decreasing values of $D_{16}$, $B_{16}$, $D_{26}$ and $B_{26}$ stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the senior author. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms(Mx) on the relevant partial differential equations of equilibrium. In this paper. the influence of the aspect ratio on the natural frequency of the composite laminated plates is studied and it is concluded that the method used is sufficiently accurate for engineering purposes.