• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.143-153
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• 2021

The corroded pier that has corrosion of the tranverse steel, main steel and lapsplice directly affects the seismic performance. The corrosion of the tranvese and main steel directly reduce the shear strength and bendig strength. If steel corrosion occurs in lap splice, the flexural strength and flexibility of existing corroded pier that are not seismic design are significantly reduced. In addition, as the axial force acting on the pier increase the shear strength. Considering these effects. In this stuydy, we cosidered steel corrosion, lap splice and axial force, for a reasonable evaluation of seismic-performance. It is confirmed that flexular failure occurs at pies where shear failure is expected to occur due to corrosion of reinforcement. These failure modes and their reason are analyzed, and necessary considerations are presented for seismic reinforcement.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.29-36
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• 2001

Same as-built drawings in national roadway bridges in Korea were examined. As a result, many bridge piers were found whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour, but the previous research works considered flexure behaviour columns only. In the study, therefore, a shear-flexure behaviour column was selected as the model pier, and quasi static test on the full and 1/2 scale models was carried out. From the test results, the scale effect on the seismic performance evaluation was analyzed, and the seismic performance of the model bridge pier without seismic details was evaluated by the capacity spectrum method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.120-128
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• 2019

It is very important to verify the seismic performance and stability of the power plant fixture in the domestic power plant, because earthquakes have increased in frequency around the world which resulted in the frequent occurrence of power plant damage caused by the failure of electric power facilities. In this study, through the on-site inspection of power plant fixation unit installed in domestic power plants, we carried out structural performance evaluation of the fixation unit anchor bolts installed on the concrete slabs. The field survey showed M12 J hook anchor bolts were used. Anchor bolt pullout and shear performance evaluation were performed based on ASTM E 488-96 standard. Moreover, artificial crack with the width of 0.5 mm was applied during the experiment based on ATM355.4 and ETAG 001. The comparison of M12 J hook anchor bolt pullout and shear test result to design value required in domestic and international design standard, show a satisfactory result. M12 J hook anchor pullout and shear performance was found to be about 35% and 7%, respectively, higher than the required design value.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.6
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• pp.455-462
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• 2013

The effects of earthquakes can be devastating especially to existing structures that are not based on earthquake resistant design. This study proposes a steel grid shear wall that can provide a sufficient lateral resistance and can be used as a seismic retrofit method. The pushover analysis was performed on RC structure with and without the proposed steel grid shear wall. Obtain the performance point that the target structure for seismic loads applied to evaluate the response and performance levels. The capacity spectrum at performance point is nearly elastic range, so satisfied the performance objectives(LS level). And response modification factor(R factor) were calculated from the pushover analysis. The R factor approach is currently implemented to reflect inelastic ductile behavior of the structures and to reduce elastic spectral demands from earthquakes to the design level. The R factor increases from 2.17 to 3.25 was higher than the design criteria. As a result, according to reinforcement by steel grid shear wall, strength, stiffness, and ductility of the low-rise RC structure has been appropriately improved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.189-196
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• 2018

Degraded shear performance of reinforced concrete members with recycled coarse aggregate (RCA) compared to flexural strength is a problem. To address this, steel fibers can be used as concrete reinforcement material. In this study, the strength and deformation characteristics of SFRC beams using RCA were to be determined by shear tests. Major experimental variables include the volume fraction of steel fiber (0, 0.5%, 1%), the replacement rate of RCA (0%, 100%), and the shear span ratio (a/d = 1, 2). As a result of the experiment, the shear strength of the specimen increased as the rate of mixing steel fiber increased. For specimens with RCA and 1% steel fiber, the maximum shear strengths increased by 1.77 - 6.25% compared to specimens with normal coarse aggregate (NCA). On the other hand, at 0-0.5% steel fiber, the shear strengths of RCA specimens were reduced by 24.2% to 49.2% compared to NCA specimens. This indicates that reinforcement with 1% volume fraction of steel fiber greatly contributes to preventing shear strength reduction due to the use of RCA.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.5
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• pp.61-69
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• 2007

The main purpose of this study is to provide a basic information for the seismic capacity evaluation and the seismic design of low-rise reinforced concrete (RC) shear wall buildings, which are comprised of a pilotis in the first story. In this study, relationships between strengths and ductilities of each story of RC buildings with pilotis are investigated based on the nonlinear seismic response analysis. The characteristics of low-rise RC buildings with pilotis are assumed as the double degree of freedom structural systems. In order to simulate these systems, the pilotis is idealized as a degrading trilinear hysteretic model that fails in flexure and the upper story of shear wall system is idealized as a origin-oriented hysteretic model that fails in shear, respectively. Stiffness properties of both models are varied in terms of story shear coefficients and structures are subjected to various ground motion components. By analyzing these systems, interaction curves of required strengths for various levels of ductility factors are finally derived for practical purposes. The result indicates that the required strength levels derived can be used as a basic information for seismic evaluation and design criteria of low-rise reinforced concrete shear wall buildings having pilotis structure.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.637-646
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• 2016

In this study, slant shear tests for the prism specimens strengthened with ultra-high performance fiber reinforced concrete (UHPFRC), normal- and high-strength concrete were performed to evaluate the interfacial shear strength between old and new concrete substrate. Test parameters are the roughness of surface, concrete strength, and fiber volume fraction of UHPFRC. The surface of the concrete was roughened by shot blasting. Test results showed that the adhesion bond resistance of the specimen with a roughened surface was very large compared to that of the specimen with a smooth surface. In addition, the interfacial shear strength appeared to be affected by the concrete strength rather than the fiber volume fraction. For the roughened surface by shot-blasting method, interfacial shear resistance exceeded the upper limit which is presented in current design codes even if the shear-friction reinforcements are not provided. Based on the test results, it is applicable to use the current concrete design codes to achieve the shear-friction design for the interface between conventional concrete and UHPFRC. However, for the surface which is not processed, it would be appropriate to provide additional shear-friction reinforcement.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.45-52
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• 2012

A variety of retrofit material such as CFRP, GFRP, and PolyUrea have been developed for strengthening RC structures and infrastructures. From previously reported research results, the capacity of strengthened concrete structures was dictated by the behavior of the interface between retrofit material and concrete. In this study, bond-shear test was carried out to estimate the bond behavior between retrofit material and concrete using a newly developed test grip. The test results of load and slip relation and energy absorption capacity of each retrofit material were obtained. These test results will provide basic information for retrofit material selection to achieve target retrofit performance.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.755-763
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• 2008

The purpose of this study is to investigate the structural performance of doubly reinforced composite beams with steel fiber concretes and steel angles. For this purpose, total 6 specimens whose variables are shear span-to-depth ratio, existence of shear reinforcement, and shear reinforcement details, are made and tested. All specimens are constructed of steel fiber concretes with specified compressive strength of 30 MPa and steel fiber volumn content of 1%. From the experimental results, structural performance of doubly reinforced composite beams are evaluated in terms of strength, stiffness, ductility, and energy absorbing capacity. For the better structural performance, it is recommended that the composite beam is designed with diagonal shear reinforcement.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.5
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• pp.23-32
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• 2012

Research on steel plate concrete (SC) structures for the modularization of nuclear power plants have been performed recently in Korea. In this study, the seismic capacity and stiffness characteristics of unstiffened SC shear walls under the effects of earthquakes were investigated through static pushover tests. Failure modes, sectional strength, and stiffness characteristics of SC structures under lateral loads were inspected by analyzing the experimental results. The strengths obtained by the experiments were also compared with those derived by the design code of the SC structures. One of the main failures of unstiffened SC shear walls was found to be the type of bending shear failure due to the debonding of the steel plate at the concrete interface. The ductility capacity of SC structures was also confirmed to be improved, which is considered to be a confining effect on steel plates in the longitudinal behavior of SC structures.