• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.393-398
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• 2000

To use concrete box culverts effectively, precast goods are manufactured at a factory, then linked and anchored with prestressing tendon at a field. However, the corrosion of rebar and prestressing tendon in the box culverts utilizing portland cement concrete is issued when the cracks occur at a underground water level. It has been reported that reported that expansive concrete, compared with portland cement concrete, has many structural advantages such as increasing capacity of watertight, controling initial crack and improving durability due to its property of expansion. During flexure test with RC beam made from expansive concrete, in the case of a constant section of concrete element, the lower steel ratio is, and in the case of a constant steel ratio, the more incremental the section of concrete element, the more incremental the amount of chemical prestress by expansive concrete is. At the segment of the box culverts using expansive concrete, the numbers of crack and its gap is reduced, and ultimate load and initial crack load is much larger than the segment at which expansive concrete is nor used. Also lay-out of tendon with a curvature generate upward force so that deflection is reduced. Through the whole procedure, it could be confirmed that performance precast box culvert by means of using expansive concrete is improved.

• Magazine of the Korea Concrete Institute
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• v.10 no.5
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• pp.47-57
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• 1998

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.153-160
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• 2008

Fracture of prestressed concrete beams is studied with a novel and robust three-dimensional meshfree method. The meshfree method describes the crack as a set of cohesive crack segments and avoids the representation of the crack surface. It is ideally suited for a large number of cracks. The crack is modeled by splitting particles into two particles on opposite sides of the crack segment and the shape functions of neighboring particles are modified in a way the discontinuous displacement field is captured appropriately. A simple, robust and efficient way to determine, on which side adjacent particles of the corresponding crack segment lies, is proposed. We will show that the method does not show any "mesh" orientation bias and captures complicated failure patterns of experimental data well.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.235-240
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• 2008

PSC box girder bridges are built through the repetitive manufacturing process of concrete segment. However, during the initial segment manufacturing stage, design change may occur frequently due to design errors and interferences between components, resulting in the extension of segment manufacturing period. This paper aims to verify the manufacturing process of PSC box girder segment by 3D simulation technique. All the components of a segment were modelled and assembled by simulation technique and then, some design errors were found and revised appropriately to optimize the manufacturing process of segment. Consequently, 3D simulation technique would be promising to improve the quality of the segment and to reduce its manufacturing time and cost.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.61-69
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• 2010

Unbonded precast concrete piers have better seismic performances than conventional reinforced concrete piers. In this research, seismic performances of unbonded precast prestressed concrete piers are analyzed using OpenSEES. Main parameters of analysis are concrete strength, jacking force ratio, ratio of tendon, and size of precast segment. In results, as the ratio of tendon and jacking force ratio increase, the flexural strength increases at softening state and ultimate state. Concrete strength and size of precast segment are negligible. But initial jacking force ratio leads to early yielding of prestressing tendon. Since compressive strain in core concrete is much less than ultimate strain, it can be expected that the amount of transverse steel reinforcement is to be reduced in comparison with conventional reinforced concrete column.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.186-189
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• 2003

Precast Segmental method was developed in germany 1950s. This method has been adoptted in long span girder mainly owing to easy construction effect. But, so far, The limit exists that this method is constructed in a portion of span and hard conveyance and foundation. This study was performed to analysis behavior difference of two rectanglar section girder, spliced girder that was jointed 5-sliced 0.8m segment and monolithic girder that was produced in one body 4m span

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.337-354
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• 2013

For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.624-629
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• 2008

When TBM excavates a tunnel, existing concrete lining segments are used as supporting structures for driving force. Axial stress on the lining segments are apt to be large in case of direct driving force. However, it drastically decline as it is farther and father from TBM and later, it tends to converge after a certain point. Such tendencies show similar results of finite element analysis. At the initial intervals, the values of finite element analysis are larger, while at the later intervals, the actual stress values are larger. It concludes that such tendencies are attributable to that the concrete lining segments have partially burst and cracked in the axial direction at the initial intervals. And differences of stresses at the later intervals are created by the changed plasticity of ground and the friction on the external sides of the lining segments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.233-242
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• 2011

This study aims to evaluate the applicability of high-strength concrete mixed with blast furnace slag to shield segment lining in order to improve its performance and economic efficiency. Especially, it was also intended to derive the optimum replacing ratio of ground granulated blast furnace slag to ordinary cement as well as the optimum steam curing condition for shield segment concrete with the design strength of 60 MPa. From a series of experiments, the condition of 50% replacement of ordinary cement by ground granulated blast furnace slag and unit water content of 125 kg/$m^3$ was proposed as the optimum mixing condition. Comparing with standard curing conditions, it was also possible to expect approximately 110~442% strength improvement of concrete by steam curing in the same mixing condition.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.547-559
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• 2012

The concrete structural design in domestic has based on the allowable stress design (ASD) method and ultimate strength design (USD) method. Recently limit state design (LSD) method has issued and attempted to adopt in geotechnical design. Because ASD method and USD method have restriction in economic design. In this study, the generated member forces were calculated about high strength concrete segment lining based on japanese LSD code. And it compared with domestic USD code for identifying the economic design possibility of LSD and domestic applicability. In analysis results, the aspect of moment had generated similarly each other but the member forces of japanese LSD code were decreased (26.0% of moment and 26.7% of shear force) comparing with USD method. For that reason, possibility of economic segment design with stable condition were identified.