• Journal of KIBIM
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• v.7 no.1
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• pp.1-8
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• 2017

Aesthetic design guidelines of bridges were developed in many countries. As iconic structures, bridges need to be attractive and durable as they serve many generations. In this paper, a new design process of concrete structures considering 3D shapes and texture was proposed. The 3D design needs to consider function, economy, advanced technology, tradition and local culture. 3D printers enable the combination of artistic design and engineering design for concrete structures. Parametric modeling with iconic design was utilized to produce 3D formworks. As a pilot project, a railway bridge girder was designed and the proposed technologies were applied. Detail requirements to improve constructability and quality of concrete surfaces were derived. From the pilot applications, design guidelines were suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.815-820
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• 1998

Many composite girder bridges have been constructed for about thirty five years. Nowadays they are aged or deteriorated because of th increase in traffic and vehicle loads. In this study, the effect of strengthening with glass fiber sheet is investigated to estimate the possibility for appling for damaged prestressed concrete bridges. One normal and eight cracked specimens which had been preloaded were tested. The cracked specimens were strengthened with either external prestressing or bonding glass fiber sheet, or using both methods. The results showed that the maximum loads are almost same for both methods. So it seems that the strengthening with glass fiber sheet can be used for strengthening damaged prestressed concrete girders. It is important that proper devices should be selected to prevent glass fiber sheet from premature bonding failure below its maximum load, which is similar to end anchorage problem in external prestressing method. It is proved that the devices proposed in this paper have sufficient anchoring capability to increase load carrying capacity.

• International Journal of Railway
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• v.3 no.1
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• pp.1-6
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• 2010

The steel plate-girder bridges with concrete gravity piers have possibilities of overturning by lateral inertial force which can be reproduced by sudden earthquake attack. This paper explores an overturning mechanism of existing concrete gravity pier onto the sandy soil in the event of lateral push-over load by in-situ experimental observation. The in-situ push-over experiment for pier with earth anchors between spread footing and rock beds exhibits a reasonable enhancement of ductility against overturning. In unanchored system, a flexural crack at cold joint of concrete pier is not developed because of the over-turning of the pier. This leads a global instability (rotation) of pier-footing system with relatively low stresses in pier itself. While a lateral load is persistently increased in anchored system, the successive flexural cracking failure at cold joint is observed even after the local shear failure of soil due to redistribution of stress equilibrium between soil and pier structure as long as a tensile action of anchor cable is active.

• Structural Engineering and Mechanics
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• v.69 no.4
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• pp.371-381
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• 2019

A hybrid prestressed segmental concrete (HPSC) girder utilizing low carbon materials was developed in this paper. This paper introduces the hybrid prestressing concept of pre-tensioning the center segment and assembling all segments by post-tensioning, as well as the development process of the low carbon HPSC girder. First, an optimized mix proportion of 60 MPa high strength concrete containing high volume blast furnace slag was developed, then its mechanical properties and durability characteristics were evaluated. Second, the mechanical properties of 2,400 MPa high strength prestressing strands and the transfer length characteristics in pre-tensioned prestressed concrete beams were evaluated. Third, using those low carbon materials and the hybrid prestressing concept, the HPSC girders were manufactured, and their structural performance was evaluated. A 30-m long HPSC girder for highway bridges and a 35-m long HPSC girder for railway bridges were designed, manufactured, and structurally confirmed as having sufficient strength and safety. Finally, five 35-m long HPSC girders were successfully applied to an actual railway bridge for the first time.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.100-110
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• 2000

In practical design of girder bridges or reinforced concrete slab bridges with T-type piers, it is usually assumed that vertical movements of superstructures are completely restrained at the locations of bearings(shoes) on a cap beam of the pier, The resulting vertical reactions are applied to the bearing for the calculation of bending moments and shear forces in the cap beam. However, in reality, the overhang parts of the cap beam will deform under the dead load of superstructures and the live load so that it may act as an elastic foundation. Due to the settlement of the elastic foundation, the actual distribution of the reactions at the bearings along the cap beam may be different from that obtained under the assumption that the vertical movements are fixed at the bearings. In the present study, investigated is the effects of elastic deformations of the T-type pier on the distribution of reactions at the bearings along the cap beam through 3-dimensional finite element analysis. Herein, for this purpose the whole structural system including the superstructure and piers as well is analyzed. It appears that the conventional practice which neglects the elastic deformations of the cap beam exhibits considerably different distributions of the reactions as compared with those obtained from the present finite element analysis. It is, therefore, recommended that in order to assess the reactions at bearings correctly the whole structural system be analyzed using 3-dimensional finite element analysis.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.1
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• pp.9-15
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• 2010

In this paper, A reinforced concrete slab bridges is analyzed by the composite laminates theory. Both the geometry and the material of the cross section of the reinforced concrete slab bridge are considered symmetrical with respect to the mid-surface so that the bending extension coupling stiffness, Bij = 0, and D16 = D26 = 0. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of rule of mixture. This slab with simple support is under uniformly distributed vertical and axial loads. In this paper, the finite difference method and specially orthotropic laminates theory are used for analysis. The result of specially orthotropic laminates theory analysis is modified to obtain the solution of the beam analysis. The result of this paper can be used for reinforced concrete slab analysis by the engineers with undergraduate study in near future.

• Steel and Composite Structures
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• v.29 no.1
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• pp.107-123
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• 2018

The conception and experimental assessment of a removable friction-based shear connector (FBSC) for precast steel-concrete composite bridges is presented. The FBSC uses pre-tensioned high-strength steel bolts that pass through countersunk holes drilled on the top flange of the steel beam. Pre-tensioning of the bolts provides the FBSC with significant frictional resistance that essentially prevents relative slip displacement of the concrete slab with respect to the steel beam under service loading. The countersunk holes are grouted to prevent sudden slip of the FBSC when friction resistance is exceeded. Moreover, the FBSC promotes accelerated bridge construction by fully exploiting prefabrication, does not raise issues relevant to precast construction tolerances, and allows rapid bridge disassembly to drastically reduce the time needed to replace any deteriorating structural component (e.g., the bridge deck). A series of 11 push-out tests highlight why the novel structural details of the FBSC result in superior shear load-slip displacement behavior compared to welded shear studs. The paper also quantifies the effects of bolt diameter and bolt preload and presents a design equation to predict the shear resistance of the FBSC.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.495-502
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• 2020

This study investigated the effects of prestressing force on the natural frequency of concrete beams considering changes in the self-weight of the beam. For this, a finite element formulation was derived to account for the increase in the stiffness of a beam-tendon system due to the axial force and deformation induced by prestressing of the tendon. The developed finite element formulation was validated with the data obtained in laboratory experiments. The experimental natural frequencies of the small prestressed concrete (PSC) beam specimens were consistent with those obtained using the proposed method. The first natural frequency increased almost linearly as the prestressing force increased. The proposed method was then applied to four actual PSC bridges typically employed in the field. Different from the laboratory specimens, the first natural frequencies of the actual PSC bridges barely changed or increased with increasing prestressing force. The results of an analytical parametric study showed that the increase in the natural frequency strongly depended on the magnitude of the prestressing force relative to the total weight of the structure. Thus, the variation in the natural frequencies of the actual PSC bridges with high total weight relative to the prestressing force was negligible due to the application of the prestressing force.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.85-98
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• 1993

A method of analysis for the material and geometric nonlinear analysis of planar prestressed concrete cable-stayed bridges including the time-dependent effects due to load history, creep, shrinkage, aging of concrete and relaxation of prestress is described. The analysis procedure, based on the finite element method, is capable of predicting the response of these structures through elastic, cracking, inelastic and ultimate ranges. The nonlinear formulation for the description of motion is based on the updated Lagrangian approach. To account for the material nonlinearity, nonlinear stress-strain relationship and cracking of concrete, nonlinear stress-strain relationships of reinforcing steel, prestressing steel, and cable, including load reversal are given. Results from a numerical examples on ultimate analyses of cable-stayed bridges are presented to illustrate the analysis method.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.152-161
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• 1994

Most widened bridges have been constructed by the joining-construction method that makes new and existing bridges structurally a single structure. Since the joining-construction method has several problems in design and construction viewpoint, this study is conducted in order to investigate the structural behaviors of RC slabs, which are widened and influenced by traffic-induced vibration of existing bridge during placing and curing of new concrete, with the prototype flexural strength test and FEM analysis. It was found that cracks are generated in construction joint at low applied load and that stress concentration at the joints and slips between steel bar and concrete are occured. But, the decreasing of load carrying capacity is negligible according to the traffic-induced vibration as well as the difference of construction method.