• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.363-375
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• 2019

Since the double-deck tunnel is deeply constructed in the city, it is necessary to secure the installation space of air supply and exhaust, escape passage stairs, elevator, distribution facilities and connection tunnels in the vertical shaft for the double-deck tunnel. Also, in order to minimize the effect of construction on adjacent area, it is necessary to construct the concrete structures at high speed in vertical shaft after tunnel excavation. Therefore, the slabs and the stairs in vertical shaft are needed to be constructed using precast concrete, and the rapid construction techniques of bracket for supporting the inner precast structure are needed. The bracket installation methods include cast-in-place concrete, precast concrete and steel. In this study, the improvement of the steel brackets with good economical efficiency and good workability was carried out in consideration of the improvement of the construction speed. We have developed a new bracket that is optimized through bracket shape improvement, anchor bolt position adjustment and quantity optimization. As a result of the structural performance test, it was confirmed that the required load supporting capacity was secured. As a result of structural performance test for bar type anchor bolt and bent anchor anchor bolt, it was confirmed that the required load carrying capacity was secured and that the load bearing capacity of bent anchor bolt was large.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.500-507
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• 2001

In this study, Interaction among each element was construed by the unit of new stiffness matrix to analyze the finite element about Japanese precast concrete slab track and improved slab track. Dynamic analysis which is assumed a static analysis and a trainload on the transverse and the longitudinal load of the train into a series periodic function was performed by using the common program. And then, the difference of the movement between an improved section and an existing structure type was realized. Longitudinal static analysis indicated that the stress of the improved section is smaller than that of the protrusion of the existing slab track. And static and dynamic analysis on transverse load showed a little decrease of the displacement on new slab track. But the dynamic analysis result showed that new track system was considerably decreased by 30% compared with the existing Japanese slab track.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.55-64
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• 2009

Recently, concrete track is replacing ballast track for efficient and economic maintenance of track. It considerably offer less maintenance, a longer service life and reduced life-cycle costs. With the aim of achieving high-quality track construction work, of developing tools for quality assurance in new construction and for later technical inspection of material condition, a quality strategy has to be developed. For these purpose, NDT which is using the seismic wave has carried out in situ studies in the test construction section. The used NDT are SASW test, impact echo test and continuous impact echo test. The test is performed 5,353 times on 49 pre-cast concrete track panels to verify the stiffness structure and grouting efficiency of the track structure. To conclude, because of the non-homogeneous characteristic of concrete material. it is restricted to apply the elastic wave test at some aspect. However it is possible to acquisite a sufficient reliability about structural stiffness and grouting efficiency of concrete track.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.313-322
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• 2007

The PCS system, which consists of precast concrete column and steel beam, is a kind of composite structural systems. In this paper, experimental study has been conducted to analyze seismic performance of bolted beam-to-column connections for the PCS system. Based on experimental results from the seismic testing of eight interior PCS specimens, it shows that behavior of PCS system is satisfactory to seismic performance criteria of ACI such as strength deterioration, stiffness degradation and energy dissipation capacity except initial stiffness. All of the specimens maintain their strength at large levels of story drift without significant loss of stiffness and show high ductility level for inelastic behavior. The energy dissipation capacity is two times greater than requirement of ACI criterion. But the initial stiffness of all specimens does not satisfy ACI criterion, and this phenomenon is similar to the other composite structural systems such as RCS, CFT system.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.103-111
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• 2024

Due to the recent increase in domestic seismic activity and the proliferation of PC structure buildings, there is a pressing need for a fundamental study to develop and revise the design criteria for Half-PC slabs. In this study, we propose criteria for determining the rigid diaphragm based on the aspect ratio of Half-PC slabs and investigate the structural effects based on the presence of chord element installation. This study concluded that Half-PC slabs with an aspect ratio of 3.0 or lower can be designed as rigid diaphragms. When chord elements are installed, it is possible to design Half-PC slabs with an aspect ratio of 4.0 or lower as rigid diaphragms. In addition, the increase in the aspect ratio of the Half-PC slab leads to a decrease in the in-plane stiffness of the structure, confirming that the reduction effect of the maximum displacement in force direction (𝜟_max ) due to the increase in wall stiffness is predominantly influenced by flexibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.459-467
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• 2016

Recently, new open-cut modular construction method, which is built within a 5~7m depth below the road, was proposed for the near-surface transit system to ensure the economic feasibility of underground structures. In this paper, the precast modular construction method was developed for the low-cost and rapid construction of underground structures. For the experiment on the flexural performance of the modular slab connections, a total of eleven specimens were fabricated according to the test variables; section shape, joint type, lap length, and transverse reinforcement. The test results were compared with those of the specimens without loop joints. To verify the performance of the slab connections, the 4-point loading tests of precast RC members with loop joints were conducted. As a result of the test, the flexural performance of the half-depth specimens with a 200mm lap length of loop joints were confirmed to be similar to those of the specimens without joints.

• Land and Housing Review
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• v.5 no.2
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• pp.91-97
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• 2014

An experimental program was initiated to investigate the structural capacity of PC (Precast Concrete) beam-column joints used for the underground parking structure. Static testing of 4 typical PC beam-column joints specimens was conducted. Specimens were designed to span a range of parameters typically encountered for such members, based on findings from the survey of existing PC joint details used in the construction fields in Korea. The specimens were four by their joint types and testing parameters. The specific structural behavior germane to each specimen, and general observations on overall member behavior as a function of the considered parameters, are reported. From the results of tests on four PC joints specimens, the beam-column joints of PC structure used for the underground parking building was found to have similar structural capacities when comparing to the cast-in-place concrete system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.175-184
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• 2011

To take advantage of reduced on-site construction periods and minimize traffic impacts various types of steel grid composite deck have been developed since 1930's. Modular prefabricated unfilled grid decks permit a long-distance transportation and construction under unfavorable condition, for example, in mountainous regions due to its comparatively light-weighter structure than fully filled grid deck. In this study bending tests of unfilled grid decks for the deck member of various kinds of infrastructure are carried out, bending strength and behaviour of composite action are experimentally evaluated. In this bending test, design variables are considered, such as type of shear connection between steel grid and concrete slab, spacing between cross bars and thickness of concrete slab. Through test results bending strength and behaviour of composite action are evaluated, reference data for proper type of shear connection and other details of the deck, such as spacing between cross bars, are obtained.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.839-844
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• 2024

This study analytically analyzed the impact of underground structure displacement behavior on track damage due to adjacent excavation work, ground deterioration, and changes in groundwater level. The concrete track that was the subject of the study was analyzed for sleeper floating track(STEDEF) and precast concrete slab track(B2S). Sleeper floating track is a track structure in which the concrete bed and sleepers are voided. precast concrete slab track is a track structure that induces the elastic behavior of the rail by assembling rails and fasteners using slabs. For numerical analysis, each concrete track, from rail to concrete bed, was modeled as three-dimensional elements. In addition, the displacement behavior of the underground structure was set as a variable to analyze the damage effect on the concrete bed. Using numerical analysis, the concrete bed stress due to uplift and subsidence was analyzed, and the level of crack effect was analyzed by comparing it to the tensile strength and shear strength. As a result of the analysis, it was found that the sleeper floating track was more vulnerable than the precast concrete slab track when the same uplift and subsidence occurred. In addition, uplift and subsidence, it was analyzed that the cracks range in the sleeper floating track was large.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.10-21
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• 2014

The joint of prefabricated steel grid composite deck is composed of concrete shear key and high-tension bolts. The flexural and shear strength of the joint were experimentally evaluated only by the bending and push-out test of the joint element. In this study the lateral load transfer behavior of the joint in deck structure system is experimentally evaluated. Several decks connected by the joint are prefabricated and loaded centrically and eccentrically. In the case of centrically loaded specimens, the analysis results show that for the same loading step the rotation angle of the joint with 4 high-tension bolts is larger than the case of the joint with 9 high-tension bolts. Consequently, flexural stiffness of deck and lateral load transfer decrease in the case of specimen with 4 high-tension bolts. But, in the case of eccentrically loaded specimens, it is found that there are no significant differences in the load transfer behavior. The further analysis results about the structural behavior of the joint show that lateral load transfer can be restricted by the load bearing capacity of the joint as well as punching shear strength of the slab. Furthermore, considering that high-tension bolts in the joint didn't reach to the yielding condition until the punching shear failure, increase in the number of high-tension bolts from 4 to 9 has a greater effect on the flexural stiffness of the joint and deck system than the strength of them.