• Journal of Korean Association for Spatial Structures
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• v.15 no.3
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• pp.95-102
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• 2015

Numerical model on precast prestressed concrete (PC) hollowcore slabs using 11.3 mm diameter 7-wire stand was developed based on finite element analysis. In order to validate the modelling, previous experiment results with respect to prestressed solid concrete slabs were used and compared throughout the course of fire exposure. In addition to, the fire performance of hollowcore slabs with different aggregate types, moisture contents and compressive strength of concrete was investigated. As a result, it can be seen that the type of aggregates and moisture contents used in hollowcore slabs can affect the fire performance as well as temperature developments.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.177-184
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• 2011

This paper describes an analytical study on the design approach of PC system with continuous connections at member ends. In multi-ribbed moment resisting slab (MRS) system, double tee members are connected continuously over inverted tee beams with the continuous reinforcements placed within topping concrete. Thus, negative moments are concentrated within the narrow connection area. In order to propose a design method, experimental results of the companion study were examined using detailed nonlinear analysis. Then nonlinear static analysis was used to evaluate the partial continuity effect and the moment redistribution mechanism. Material and cross sectional properties were obtained from experimental results of the companion study. Plastic hinge properties for nonlinear static analysis were modeled with cracking moment, nominal moment, corresponding member deformations, etc. The analysis results showed that a large amount of negative moment of MRS slab can be reduced by applying partial continuity and moment redistribution in MRS joint.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.345-356
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• 2004

Open-cut method has been widely used to construct underground structures, but it causes several problems such as traffic congestion and public resentment resulting from severe construction noise and ground settlement. In many cases, it is very difficult to build underground structures safely due to the unknown locations of buried facilities such as water pipes, drainage pipes, gas pipes and high-pressure cable conduits etc. Also in open-cut method, moving buried facilities causes additional cost and extension of construction period. Therefore, this paper is to present a case study in which Tubular Roof construction Method (T.R.c.M.), a newly developed construction method for underground structures using slab steel pipes and PC wall trench, is applied for the construction of a subway tunnel in Seoul. As a result, it is found that T.R.c.M. is a construction method by which tunnels can be constructed safely without any effect on the surrounding environment and traffic flow due to the minimized construction vibration and noise.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.3
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• pp.289-296
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• 2009

Natural frequency is a key parameter to determine the seismic and wind loading of tall flexible structures, and to assess the wind-induced vibration for serviceability check. In this study, natural frequencies and associated mode shapes were obtained from measured acceleration data and system identification technique. Subsequently, finite element(FE) models for a tall reinforced concrete buildings were built using a popular PC-based finite element analysis program and calibrated to match their natural frequencies and mode shapes to actual values. The calibration of the FE model included: 1) compensation of modulus of elasticity considering the mix design strength, 2) flexural stiffness of floor slabs, and 3) major non-structural components such as plain concrete walls. Natural frequencies and mode shapes from the final FE model showed best agreement with the measured values.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.49-56
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• 1990

Todays, design of composite prestressed concrete beams is carried out by calculation of the prestressing force and its eccentricity assuming the sectional properties. However the characteristics of composite section made with a precast prestressed concrete beams and reinforced concrete slab is not reflected, so iteration method has been adopted. But its methed requires much time and labor. Accordingly, an improved design method will be presented. In this study, improved design method is proposed to design composite section directly without iterative calculation. Design examples according to the proposed design method are presented for easy application and verification of its reliability and authenticity. The results match well with the Hatcher's.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.61-70
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• 2014

Synthetic fiber reinforced concrete is applicable to many applications for construction material. In general, synthetic fibers have low tensile strength and elastic modulus, but they have many advantages such as high crack resistance, impact resistance, chemical resistance, flexural behavior and corrosion free in fiber reinforced concrete. Recently, fiber reinforced concrete with macro synthetic fibers has been used to improve performance of structures in tunnel shotcrete, precast segmental lining and bridge slab and precast concrete structures. This study investigated the influence of bundled type polyamide fiber reinforced concrete on the flexural behavior in accordance with ASTM C 1609 and KS F 2566 standards.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.81-89
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• 2008

Shear test procedure for concrete-dowel interaction was proposed along with determination of dowel support reaction factor or shear spring stiffness constant using the spreadsheet example. For this task, three AASHTO-type standard specimens were prepared to simulate behavior of the jointed concrete pavement. A side support system was adopted to minimize twisting of the test specimen which had been observed in a preliminary test. A typical elastic behavior of the dowel-concrete interaction was observed from several test loops of loading, unloading and reloading procedures. However load versus slab displacement represents to be nonlinear. Test results show that the dowel support reaction factor ranges from 550-880 GN/m3, which is 1.4-2.2 times greater than 407GN/m3 proposed by Yoder and Witczak. This is because less torsional distraction was occurred with the help of a side support system adopted in this experiment. The dowel support reaction factor or shear spring stiffness constant obtained from the procedures proposed in this paper may be used as a reference data for the structural analysis of jointed concrete pavement.

• Journal of Korean Society of Steel Construction
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• v.14 no.3
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• pp.463-470
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• 2002

The TEC-Beam system is a composite beam consisting of structural tee, precast concrete, and cast-in-site reinforced concrete slab. The preliminary test of the proposed system was performed for simple beams, showing good behavior. However, for the field application of the system. TEC-Beam - RC column connection was required to produce a mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection wherein the section of the TEC-Beam was enlarged and the lower part reinforced. Two setups of the proposed system were experimentally investigated. using the anchorage length of reinforcement., i.e., length of the increased section, as test parameter. It could be concluded from the result that the proposed system shows good structural behavior, with potential applicability in the field.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.51-58
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• 2002

To reduce the story height for high-rise buildings, the TEC Beam is developed as a new composite beam composed of structural tee, precast concrete, stirrup, and site-in-cast reinforced concrete slab. The preliminary test of the proposed system was performed for simple beams and it showed a good behavior. However, for the field application of the system, it is required to develope a steel moment resisting connection using steel brackets on which upper rebars of the TEC BEAM are anchored. In this paper, three types of the proposed system are experimentally investigated. The parameters of the test are as follows: (1) the spacing of transverse bars, (2) the ratio of width of rebar's layer to bracket length. Specimens were classified as semi-rigid full strength by the Eurocode 4. It could be concluded that the proposed moment resisting system shows a good structural behavior and may be applicable in the filed.