• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.673-678
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• 2005

ACI 318 (1999) defines three types of moment frames: Ordinary Moment Resisting Concrete Frame (OMRCF), Intermediate Moment Resisting Concrete Frame (IMRCF), and Special Moment Resisting Concrete Frame (SMRCF). OMRCF is the most popular type of moment frame in mild seismic zones that requires the least detail and design requirements. This study focuses on the seismic performance of Ordinary Moment Resisting Concrete Frames (OMRCF) designed only for gravity loads. For this purpose a 3-story OMRCF was designed in compliance with the minimum design requirements in ACI 318 (1999). An one third 3 story specimen was made and tested. For scaled model, the similitude law of true replica was applied. The specimen was loaded with quasi-static reversed cyclic lateral loading. The overall behavior of OMRCF is quite stable without abrupt strength degradation. It is found that tested frame has the base shear strength larger than the design base shear for seismic zone 1, 2A and 2B calculated using UBC 1997.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.239-245
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• 2006

The steep slopes have been increased of new roads, industrial site development and large scale residential development. The preservation administration and steep slope construction are currently investigated by many researchers in Korea. However, concrete retaining wall or reinforced soil (i.e. Block or Pannel) are being applied for the steep slope, which results in the front face form of the structure being limited. This research investigates the method that can make up afforestation environment-friendly circumstances during the construction of steep slope structure. It is considered that steep slope reinforced structure would be possible based on the monitoring results about earth pressure, horizontal displacement and consolidation quality generated during the construction of whole constructing reinforced structure. Also, there no problems in grassy surface, drainage, and deformation in spite of rainy season after construction period and until now. So that the seeding soil layer surface reinforced soil method could be adopt for steep slope reinforced structure and others.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.220-227
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• 2021

PCT (Power Cable Tunnel) and UT (Utility Tunnel), which are non-transport underground infrastructures, are mostly RC (Reinforced Concrete) structures, and their durability decreases due to the deterioration caused by carbonation over time. In particular, since the rate of carbonation varies by use and region, a predictive model based on actual carbonation data is required for individual maintenance. In this study, a carbonation prediction model was developed for non-transport underground infrastructures, such as PCT and UT. A carbonation prediction model was developed using multiple regression analysis and deep neural network techniques based on the actual data obtained from a safety inspection. The structures, region, measurement location, construction method, measurement member, and concrete strength were selected as independent variables to determine the dependent variable carbonation rate coefficient in multiple regression analysis. The adjusted coefficient of determination (Ra2) of the multiple regression model was found to be 0.67. The coefficient of determination (R2) of the model for predicting the carbonation of non-transport underground infrastructures using a deep neural network was 0.82, which was superior to the comparative prediction model. These results are expected to help determine the optimal timing for repair on carbonation and preventive maintenance methodology for PCT and UT.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.715-722
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• 2019

The durability of concrete structures deteriorates due to the corrosion of rebars and concrete deterioration by harmful ions (CO₃^2-, Cl^-, SO₄^2-) penetrating and diffusing from the outside into concrete. Therefore, the use of surface-protection finishing mortar is very important for preventing or delaying the deterioration of concrete. In this study, the possibility of the prevention of deterioration or delay of deterioration of concrete was investigated using natural latex modified with silica sol and calcium ions for cement mortar, which can be used to repair the mortar of deteriorated concrete or for finishing the mortar of concrete. As a result, fine calcium silicate hydrate was formed in the pores of the cement material due to the calcium ions and silica sol components contained in the modified latex component that reduce the pore distribution of the cement mortar, thereby reducing the penetration and diffusion of harmful ions (CO₃^2-, Cl^-, and SO₄^2-). Furthermore, the latex component was found to be present in the pores of the cement to improve the alkali resistance and carbonation resistance.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.493-500
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• 2004

FREP(Fiber Reinforced Epoxy Panel) are used for strengthening the damaged RC beams due to its good tensile strength, low weight, resistance to corrosion, and easy applicability. This study sets up structure equation for FREP bending reinforcement before and during the usage of RC beam. It finds the difference and finds the mechanical characteristics of rip-off failure that is caused by stress concentration in reinforcement material cutting part to estimate the performance of bending reinforcement. The result of this research can be summarized as two main consequences. The main failure of FREP reinforced concrete beam is rip-off failure and it evaluated rip-off failure of RC reinforcing bean based on the test and analytical conditions of this study. It found that stress was concentrated due to rapid change of bending rigidity in reinforced cutting part as a result of excessive reinforcement thickness of FREP. It resulted in rip-off failure. It means that it should evaluate the rip-off failure when designing reinforcement. It analyzed the reinforcement effect according to reinforced period for FREP. It found that reinforcement effect of P-Type that was reinforced during the usage decreased compared to I-Type that was reinforced before the usage. So when reinforcing a existing structure that is being used, it should consider the stress that is produced due to the fixed load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.112-119
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• 2011

Sheaths are arranged in the web and lower part of prestressed-concrete girder bridges, and prestressing wires and concrete are indirectly bonded together by filling interior parts of the sheaths. However, when the filling is not sufficient, water can penetrate the interior parts of the sheaths and, thereby, prestressing wires can be corroded or transverse cracks would occur around sheaths by the freezing and thawing action of the penetrated water. Therefore, it is an important element in maintenance management of structures to find out the sheaths unfilled with grout early after construction. In this paper, in order not to damage bridge members, the impact-echo method with a new approach in application is used to probe sheaths unfilled with grout for real structures. The location of sheaths is first estimated with reinforcing bar probing instrument of radar type and the measurement locations of sheaths are determined. By sending elastic wave to the side of girders and receiving the response, the location of the unfilled part of a sheath was estimated from the difference between high frequency peak and twice the resonance frequency indicating thickness. To verify the location of void estimated by the impact-echo method, pictures were taken by an industrial fiber scope after drilling a hole.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.94-105
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• 2013

Recently, the construction industry has been changed in such a way that the cost for bridge construction should be optimized or reduced. Therefore, bridges are required be cost-effective in terms of initial construction as well as in the maintenance during service stage. In order to reduce the cost for bridge construction, the Rahmen typed structure, in which the bridge components from superstructure to substructure are integral, has many advantages to reduce the size of structural members including girders, since the loadings from superstructure may be transferred to substructure through the connecting rebars such as stud, etc. This paper studied on the continuous Up and Down Prestressed Concrete (UD PSC) girder bridge in which the reinforced concrete pier cap is integral with the part of girders in superstructure. In previous studies, it is known that the structural behavior of continuous UD PSC girder bridge is quite different compared to the one of the bridges with conventional bearings or shoes to support the loading from girders. Nevertheless, it has hardly been studied about the structural behavior of bridge with UD PSC girder. Therefore, in this study, various dynamic behaviors of continuous UD PSC girder bridge with integral pier cap have been analyzed using numerical method. Furthermore, an equation to evaluate the impact factor is suggested for the UD PSC girder bridge which has two to three continuous spans.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.525-532
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• 2012

The recently constructed buildings are ensuring seismic safety with enhanced design criteria. But, the buildings unapplied enhanced design criteria are very weak. In this study, steel grid shear wall is proposed as a solution of seismic retrofit to ensure safety of the existing buildings for the earthquake. And the structural performance experiments were carried out under axial force and cyclic lateral loads. The two specimens were made of a reference RC frame and steel grid shear wall in-filled RC frame. The test setup configured with two dynamic actuators, for the axial force with a 500kN capacity actuator and for the cyclic lateral load applied with the 2,000kN actuator. Compared with control specimen, the strength, stiffness, ductility, energy dissipation capacity of the seismic retrofit structures is evaluated.

• Fire Science and Engineering
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• v.25 no.1
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• pp.7-12
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• 2011

As recent buildings are getting more high-rise and larger, steel structures, not a reinforced concrete structure, for columns and beams among the main structural members in a building are being widely used. Steels used for the main members of a building are constructed with a fire-resistive structure by applying them with fire-resistive coatings. The introduction of a simple test method that can verify the performance of fire-resistive material constructed on a site without conducting a fire-resistant test(real scale fire test) is needed and this study derived a site analysis method possible to make a rapid and scientific analysis through the analysis of components (instrumental analysis) concerning tire-resistive materials. the possibility of application of it in analyzing congruence over site construction materials by recognizing it as a standard material after securing an inherent fingerprint area of tire-resistive materials of which performance was verified in the concrete through thermal analysis was proved through experiments. This research result can be minimize of casualties, who is harmed to building collapse according to structures fire.

• Geotechnical Engineering
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• v.2 no.3
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• pp.67-78
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• 1986

This paper presents how to determine the system reliability of a typical shallow foundation constituted four potential correlated failure modes of hearing capacity (BCM), consolidation settlement (CSM), moment (MFM), and tension shear (PCM). Through the idenfication of the distinct and different modes and evaluation of range of system reliability, the obtained conclusions are as follows; 1. The CSM and the PCM are the lowest and highest of reliability indices of single performance function, and the BCM and the MFM are medium of them. 2. For the correlated failure modes, the hi-modal bounds Is narrower and lower of failure probability than the unimodal bounds. Not to be overestimated, therefore, the system reliability should be based on the second-order bounds using correlated performance functions.