• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.45-53
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• 2013

In this study, steel-pier's structural behavior by design variables of ribs were analyzed in order to improve structural details of ribs supporting double base plates. A numerical analysis was conducted using commercial FE analysis program. Anchor bolts and reinforced bars were made of BEAM element, and coefficient of friction was applied to contact surfaces. After that, the analytical result was compared with experiment of previous study to verify analysis methods. Steel-pier's load-displacement relation was analyzed according to various rib's design variables (rib's central angle, height, thickness) by using proven analysis methods, and proper rib's design ranges were proposed.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.903-910
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• 2005

In recent years, fiber reinforced polymer(FRP) plates have shown a great promise as an alternative to steel plates for reinforced concrete beam rehabilitation. Reinforced concrete beams strengthened with externally bonded FRP sheets to the tension face can exhibit ultimate flexural strengths several times greater than their original strength if their bond strength is enough. Debonding failure, however, may occur before the strengthened beam can achieve its enhanced flexural strength. The purpose of this paper is to investigate the debonding failure strength of FRP-strengthened reinforced concrete beams. An analytical procedure for calculating debonding load between concrete and strengthening FRP is presented. Based on the local bond stress-slip relationship in the previous studies, uniform bond stress is assumed on the effective bond length. The analytical expressions are developed from linear elastic theory and statistical analyses of experimantal results reported in the literature. The proposed method is verified by comparisons with experimental results reported in the previous researches.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.167-177
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• 1997

In thtx design of ductile moment -1csist1ng frnmcls (DMRFs) f'ollow~ng the. stlong columnweakbeam design philosophy, it is desirable that the joint and column remain essentiallyelastic in order to insure proper energy dissipation and lateral stability of the structure.Thv joint has been identifid as the "weak link: in DMRFs because any stiffness orstrength deterioration in this region can lead to substantial drifts and the possibility ofcollapse due to t'-delta effects. h3oreove1.. the tngintw is faced with the difficult task ofdetailing an element whose size is determined by theframing members, but \vhich mustresist a set of loads very different from those used in the design of the beams and columns.Four 3 -scale beam-column-slab joint assemblies were designed according to existing cod\ulcornerrequirements of' ACI 318-89. representing perimeter joints of DMRFs with reinforced highstrength concrete. The influence on aseismic behavior of beam-column joints due tomonolithic slab, has been investigated.lab, has been investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1030-1038
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• 2007

This paper presents the measurement results of strength of electromagnetic wave for GSM-900/GSM-1800 band which is used in Europe. The Giryong village and Sosan field are selected as candidate regions according to the measurement results in Gijang-gun, Busan. The vertical polarizations is about 12 dBm higher than horizontal polarization at two candidate places, and it is measured 25 dBm lower than urban. The maximum value of measured strength of vertical polarizations in the cellular/GSM-900 bands are -65 dBm at Giryong village and -69 dBm at Sosan field, respectively. The maximum value of measured results of PCS/GSM-1800 bands are -90.5 dBm at Giryong village and -85 dBm at Sosan field, respectively, We confirm that the receiving strength of electromagnetic wave are very weak below -65 dBm at two candidate places and the signals of GSM frequency bands not affect to conversional system, then it is considered as a suitable place for GSM mobile field test.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.525-528
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• 2008

For well-constructed concrete, its service life is a long term and it has an enough durability performance. However, for cracked concrete, it is clear that cracks should be preferential channel for the penetration of aggressive substance such as chloride ions according to author's previous researches. In order to enhance the lifetime of cracked concrete, critical issues in the performance of the concrete is the risk of chloride-induced corrosion. Even though crack width can be reduced due to the high reinforcement ratio, the question is to which extend these cracks may jeopardize the durability of cracked concrete. If the size of crack is small, surface treatment system can be considered as one of the best options to extend the service life of concrete structures exposed to marine environment simply in terms of cost effectiveness versus durability performance. Thus, it should be decided to undertake an experimental study on the effect of different types of surface treatment system, which are expected to seal the concrete and the cracks to chloride-induced corrosion in particular. In this study, it is examined the effect of surfaced treated systems on chloride penetration through microcracks. Single surface treatments of penetrant or coating and double application were considered as an experimental variation. RCM (Rapid Chloride Migration) testing is accomplished to visualize chloride penetration via cracks.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.753-756
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• 2008

Recently, construction work period reduction is a very important topic of construction business circles. Because that is just big cost reduction. There is an important part of construction to decide the removal time of form. For prediction strength for removal form, P type schmidt hammer method and maturity method is used that. In case early strength prediction of maturity method, that is problem. Because setting duration of concrete is not proper considering. So this experimental study is a coefficient(A) of maturity method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.117-120
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• 2008

Recently, according to the increasement of high-rise building construction and domestic situation, requirements of rapid cycle construction are increasing. For more economical and rapid cycle construction, it is required to reduce formwork cost. So formwork have to be stripped as soon as possible. But as fresh concrete is loaded with construction load, it is likely that the structure will have problems with safety and serviceability. To reduce construction cycle economically, safety and serviceability of structure against construction load have to be considered. But as behavior of structure under construction is so complicated, behavior of structure has to be investigated according to construction stage. Therefore, through field instrumentation of apartment, behavior of structure under construction was analyzed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.309-312
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• 2008

This paper describes ultimate load tests which were performed to show the effects of prestress loss and tendon corrosion on the flexural strength of post-tensioned concrete beams and the occurrence of wire fracture. Five test specimens were fabricated in laboratory with the variations of the prestress of tendons and the loss of tendon area. For two specimens, small area of tendon at the center of the beam was exposed by using diameter 25mm drill and the exposed tendon was corroded using accelerated corrosion equipment. During the tests, deflections, crack width, and strain changes were measured and acoustic events were monitored with two acoustic sensors. Tests results show that the ultimate flexural strength of test specimens with corroded tendons is smaller than the predicted flexural strength which is calculated considering the loss of tendon area. It is considered that estimation of flexural strength of PSC beams with corroded tendons is very complicated just based on the loss of tendon area obtained by one-side visual inspection.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.13-22
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• 2004

The purpose of this study is to investigate the flexural behavior of circular concrete filled carbon tube(CFCT) columns subjected to constant axial load with the cyclic lateral load. Six numbers of composite columns were tested. Two parameters, winding angle and thickness of tube, were chosen to evaluate the flexural capacity and behavior of CFCT columns. Selected two parameters were considered simultaneously in order to evaluate the flexural behavior of CFCT columns more precisely. Flexural strength, deformation capacity, ductility and energy dissipation capacity of CFCT columns were evaluated by calculating the area of load-displacement envelop curves and load-displacement hysteresis curves obtained from experiment. Also, the ductile capacity obtained from experiment were compared to that of reinforced masonry wall for the comparison of existing structural element.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.305-312
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• 2014

The current American Concrete Institute(ACI), Canadian Standard Associate(CSA) and CEB-FIP Model Code 2010 provisions on the shear strength of a simply supported deep beam suggest that deep beams should be designed using the strut-and-tie model. Although this is a useful methodology to design members in disturbed regions, the quality of the design is highly dependent on the truss model that designers create. However, Hong et al. derived the shear strength equations of reinforced concrete deep beams. This thesis investigates the validity of the current ACI, CSA and CEB-FIP code provisions on the shear strength of simply supported reinforced concrete deep beams by comparing them with the shear strength equations proposed by Hong et al. The comparison shows that all of these code provisions provide reasonable estimates on the shear strength of concrete deep beam members and the selection of an internal truss model plays an important role on the estimation of shear strength.