• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.343-350
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• 1999

Orthotropic steel bridge decks are potentially liable to cause fatigue cracks due to weld defects, residual stresses, and in-plane or out-of-plane stresses. In particular, the cracks propagated through deckplate in longitudinal rib to deckplate joints occur at weld toe and weld root due to stress concentrations. Numerical parametric studies are performed to show the Influence of the parameters on the stress concentration at the connection between the longitudinal rib and the deckplate. The parameters include root gap, toe angle $\theta$, toe radius $\rho$, and weld penetration. This study provides a fundamental point for the improvement of fatigue resistance and the estimation of the fatigue crack propagation in wekded joint details.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.553-563
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• 1997

A procedure is being developed for bolting plates to the sides of existing reinforced concrete beams to strengthen and stiffen them. Unlike standard composite steel and concrete beams in which there is longitudinal-partial-interaction at the steel/concrete interface (that is slip along the length of the beam), composite bolted side-plated reinforced-concrete beams are unique in that they also exhibit transverse-partial-interaction, that is slip transverse to the length of the beam. In this work, the fundamental mathematical models for transverse-partial-interaction and its interaction with longitudinal-partial-interaction are developed. The fundamental models are then further developed to determine the number of connectors required to resist the transverse forces and to limit the degree of transverse-partial-interaction in bolted side-plated reinforced concrete beams.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.235-246
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• 2005

Local buckling is a major consideration in the design of thin-walled cold-formed steel sections. The main effect of local buckling in plate elements under longitudinal compressive stresses is to cause a redistribution of the stresses in which the greatest portion of the load is carried near the supporting edges of the plate junctions. The redistribution produces increased stresses near the plate junctions and high bending stresses as a result of plate flexure, leading to ultimate loads below the squash load of the section. In singly symmetric cross-sections, the redistribution of longitudinal stress caused by local buckling also produces a shift of the line of action of internal force (shift of effective centroid). The fundamentally different effects of local buckling on the behaviour of pin-ended and fixed-ended singly symmetric columns lead to inconsistencies in traditional design approaches. The paper describes local buckling and shift of effective centroid of thin-walled cold-formed steel channel columns. Tests of channel columns have been described. The experimental local buckling loads were compared with the theoretical local buckling loads obtained using an elastic finite strip buckling analysis. The shift of the effective centroid was also compared with the shift predicted using the Australian/New Zealand and American specifications for cold-formed steel structures.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.731-740
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• 1998

Orthogonally stiffened steel plates are used for orthotropic steel decks of long-span bridges because of high degree of flexural and torsional resistances and good load-distribution behavior. An analytic study is presented for evaluating the buckling strength of orthogonally stiffened plates subjected to uniaxial compression. By using the plate theory, the buckling stress under overall and partial buckling modes, is derived. Parametric studies are performed to show the effects of the stiffness and the number of transverse and longitudinal ribs on the buckling strength. The results show quantitatively strong influence of stiffness and spacing of longitudinal and transverse ribs.

• Steel and Composite Structures
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• v.12 no.3
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• pp.261-273
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• 2012

This study proposes and examines a circular composite bridge pier for seismic resistance. The axial and flexural strengths of the proposed bridge pier are provided by the longitudinal reinforcing bars and the concrete, while the transverse reinforcements used in the conventional reinforced concrete pier are replaced by the steel tube. The shear strength of this composite pier relies on the steel tube and the concrete. This system is similar to the steel jacketing method which strengthens the existing reinforced concrete bridge piers. However, no transverse shear reinforcing bar is used in the proposed composite bridge pier. A series of experimental studies is conducted to investigate the seismic resistant characteristics of the proposed circular composite pier. The effects of the longitudinal reinforcing bars, the shear span-to-diameter ratio, and the thickness of the steel tube on the performance of strength, ductility, and energy dissipation of the proposed pier are discussed. The experimental results show that the strength of the proposed circular composite bridge pier can be predicted accurately by the similar method used in the reinforced concrete piers with minor modification. From these experimental studies, it is found that the proposed circular composite bridge pier not only simplifies the construction work greatly but also provides excellent ductility and energy dissipation capacity under seismic lateral force.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.749-757
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• 2006

Many losses of life and extensive damage of social infrastructures have occurred due to moderate and strong earthquakes all over the world. In this research various design parameters have been evaluated to develop a rational seismic design code of rectangular reinforced concrete(RC) bridge piers. It was confirmed from this study that the axial force ratio and longitudinal steel ratio were most influencing design parameters on the seismic displacement ductility from experimental results of 54 rectangular RC bridge piers, which were tested at domestic and foregin countries. However, these important parameters are not considered in the confinement steel ratio of Korea Highway Bridge Design Specification(KHBDS). The objective of this study is to propose a rational design provision for the transverse reinforcement of rectangular RC bridge piers. New confinement steel ratio is proposed by reflecting the effect of the axial force and longitudinal steel into the current code of KHBDS. furthermore, minimum transverse confinement steel ratio is also proposed to avoid a probable buckling of longitudinal reinforcing steels of RC bridge piers with a relatively low axial force. New practical code can alleviate the rebar congestion in the plastic hinge region of RC bridge pier, which contributes to construct RC bridge piers in a simple and economic way.

• Steel and Composite Structures
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• v.22 no.4
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• pp.837-853
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• 2016

This paper presents the experimental and numerical study on the distribution of transverse and longitudinal residual stresses in cold-formed thick-walled structural steel rectangular hollow sections manufactured by indirect technique. Hole-drilling method is employed to measure the magnitude of the transverse and longitudinal surface residual stress distribution, and the effects of the residual stresses are evaluated qualitatively by sectioning method. It is shown that compared to normal cold-formed thin-walled structural hollow sections (SHS), the cold-formed thick-walled SHS has similar level of residual stress in the flat area but higher residual stresses in the corner and welding areas. Both the transverse and longitudinal residual stresses tend to open the section. In order to predict the surface residual stresses in the corners of the cold-formed thick-walled SHS, an analytical model is developed. 2D finite element simulation of the cold bending process is conducted to validate the analytical approach. It is shown that in analyzing bending for thick-walled sections, shifting of neutral axis must be considered, since it would lead to nonlinear and non-symmetrical distribution of stresses through the thickness. This phenomenon leads to the fact that cold-formed thick-walled SHSs has different distribution and magnitude of the residual stresses from the cold-formed thin-walled SHSs.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.20-24
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• 2005

Due to the difficulties associated with the supply of steel plates, hot rolled coil (Steel grade: SM490A) is considered fur structural materials in replace of the existing SWS50A-M1. However, it is found that SM490A exhibits a significant anisotropy in terms of impact energy with respect to transverse and longitudinal directions. In this study, an experimental investigation is carried out to examine the relationship between the anisotropy in impact values and the fatigue strengths of SM490A with respect to the rolling direction of test specimens. All test specimens failed around 1,500,000 cycles regardless of the test specimen direction. Therefore, it is found that the anisotropy in impact energy is not related to the fatigue strength of the materials considered in this study. However, the transverse direction specimen showed more rapid brittle fracture mode compared to that of longitudinal direction specimen, and this appears to be related to the lower impact values in transverse direction.

• International Journal of Highway Engineering
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• v.16 no.2
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• pp.25-34
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• 2014

PURPOSES : This paper numerically evaluates the contribution of transverse steel to the structural behavior of continuously reinforced concrete pavements to understand the role of transverse steel. METHODS : Two-lane continuously reinforced concrete pavements with and without transverse steel were analyzed through finite element analysis with the aid of commercial finite element analysis program DIANA; the difference in their structural behavior such as deflection, joint opening, and stress distribution was then evaluated. Twenty-node brick elements and three-node beam elements were used to model concrete and steel, respectively. Sub-layers were modeled with horizontal and vertical tensionless spring elements. The interactions between steel and surrounding concrete were considered by connecting their nodes with three orthogonal spring elements. Both wheel loading and environmental loading in addition to self-weight were considered. RESULTS : The use of transverse steel in continuously reinforced concrete pavements does not have significant effects on the structural behavior. The surface deflections change very little with the use of transverse steel. The joint opening decreases when transverse steel is used but the reduction is quite small. The transverse concrete stress, rather, increases when transverse steel is used due to the restraint exerted by the steel but the increase is quite small as well. CONCLUSIONS : The main role of transverse steel in continuously reinforced concrete pavements is supporting longitudinal steel and/or controlling unexpected longitudinal cracks rather than enhancing the structural capacity.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.336-343
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• 2000

Crack behavior of steel fiber concrete(SFC) and reinforced steel fiber concrete(RSFC) specimens has been experimentally and analytical investigated. Clack behavior of RSFC beams influenced by longitudinal reinforcement ratio, volume and type of steel fiber, strenth of concrete. It can be observed from experimental result that addition of steel fiber to concrete specimen reduce crack width and increases stiffness, and thus enhances the behavior in serviceability limit states also high cyclic loading