• 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 Concrete Institute
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• v.16 no.1 s.79
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• pp.61-69
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• 2004

The bridge piers under service suffered a brittle failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or ductility. The earthquake induced lateral force results in tension which causes bond-slip failure at the lap-spliced region in circular bridge piers. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP laminated circular tube. The retrofitted piers using FRP laminated circular tube showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the analytical results on the seismic strengthening effect of circular bridge piers with poor lap-splice details and strengthened with FRP laminated circular tube. FRP's confinement effect is predicted by the classical elasticity solution for the laminated circular tube manufactured with several layers. The FRP laminated circular tube induces the flexural failure instead of a bond-slip failure of the circular reinforced concrete piers under seismic induced lateral forces. To investigate the correctness and effectiveness of analytical solution derived in this study, the analytical results were compared with the experimental data and it was confirmed that the results were correlated well each other, The effects on the confinement of FRP laminated circular tube, such as the number of layers, the fiber orientations, and the mechanical properties, were investigated. From the parametric study, it was found that the number of layers, the fiber orientations, and the major Young's modulus (E11) of the FRP laminated circular tube were the dominant parameters affecting the confinement of reinforced concrete circular bridge piers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.98-99
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• 2018

Seismic retrofitting technologies have been paid attention to structural engineers for rehabilitations of existing building structures vulnerable to seismic loading conditions. This paper introduces the traditional strengtheing method applying externally-bonded steel frames to column and beam elements, and compares with the improved scheme using the frames with additional energy dissipation systems. Throughout experimental studies, it was observed that the method can be effective for promoting the seismic performance of seismic force-resisting systems by guaranteeing strong column-weak beam mechanism. Compared to the traditional manner, it was found that the new scheme can be more efficient for confirming capacity design concept, while energy dissipation systems can provide additional damping effects corresponding to lateral deformation which occurs at seismic force-resisting systems exposed to seismic excitations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.231-237
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• 2004

Most of the masonry buildings have many structural defects under an earthquake load due to the small tensile force and ductility. In the foreign countries there are many the reinforcing methods of masonry buildings, but the glass fiber sheet reinforcements must be used due to various conditions in Korea. The purpose of this paper is to estimate the seismic capacity of masonry buildings damaged by earthquake and reinforced by Glass Fiber Sheet. On the basis of test results, the maximum base shear force and deformation of the masonry building with GFS were remarkably increased. From the comparison by existing strength equations and test data, the new strength equation of reinforced masonry buildings with GFS was developed.

• 건축구조
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• v.20 no.2
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• pp.25-28
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• 2013

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.17 no.4
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• pp.68-73
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• 2013

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.569-580
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• 2005

The postbeam joint connection of the existing steel structure moment flexible frame system did not produce sufficient seismic resistance during the earthquakes in Northridge and Kobe, and it sustained brittle fracturing on the joint connection. This study was performed to execute the high-tensile bolt share connection of H-beams web and the full-scale experiment as a parameter of the existing reinforcement of H-flange rib, by making the shape of the existing joint connection. This experiment was performed to determine the extent of the decrease of the number of high-tensile bolts and how to improve workability of the two-phase shear connection of web beam. In addition, this study was performed to enhance the seismic resistant capacity through the enforcement of rib plates. As a result of the experiment of two-phase shear connection of H-beam web and of joint connection to be reinforced by rib plates, the results of this study showed that the initial stiffness, energy-dissipation capacity, and rotational capacity of plasticity was higher than the existing joint connection. As to the rate of increasing the strength and deformation capacity, there were differences between the tension side and compression side because of the position of shear tap. However, as a whole, they have shown excellent seismic resistant capacity. Also, all the test subjects exceeded 4% (rate of delamination), about 0.029 rad (total plastic capacity), and about 130% (maximum strength of joint connection) of fully plastic moment for the original section. Accordingly, this study was considered as it would be available in the design more than the intermediate-level of moment flexible frame.

• Journal of the Korean Institute of Educational Facilities
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• v.19 no.4
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• pp.29-38
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• 2012

Recently large scale earthquake s are occurred around the world following the damage of buildings. So the interest of preparing for earthquake seismic design and seismic performance has becoming high. School buildings are though used for educational purpose; they are also used as emergency shelter for local residents during earthquake disaster. However, the current seismic design ratio of our country (Korea) is 3.7% and if massive earthquake is occurred it follows a serious damage. In order to overcome this situation, seismic performance evaluation is carried out for existing school building and an accurate and appropriate seismic retrofit is required based on performance evaluation to upgrade the existing school buildings. In this paper, nonlinear static analysis on existing school buildings for ATC-40 and FEMA-356 are carried out using the capacity spectrum method to evaluate seismic performance and to determine the need for retrofitting. In addition, after reinforcement to verify the effect of retrofit enhance the seismic performance is applied the seismic performance evaluation is carried out to verify the effect of seismic retrofit time history analysis using nonlinear dynamic analysis is also performed and nonlinear behavior of earthquake load of seismic retrofit of structures was also investigated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.46-52
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• 2018

Detail development and performance tests were conducted for the purpose of developing a damper system capable of lateral displacement control of existing frame structures. The development details are 1) ALD designed to prevent deformation of beams between columns and 2) AWD designed to control inter-story displacement. The non-reinforced BF specimen was used as a comparative study. The evaluation variables are failure mode, load-displacement curve, envelope curve, maximum strength, stiffness degradation and energy dissipation capacity. As a result, the seismic strengthening effect of ALD and AWD was confirmed. Also, it was confirmed that the method of restraining the column with the aramid sheet is superior to the improvement of the seismic performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.136-137
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• 2018

The domestic seismic retrofit guide was primally enacted in 1988, then the mandatory target have been consistently. As a result, the rate of earthquake-resistant is achieved 58.3% in public facilities. On the other hand, the rate of earthquake-resistant is low as 24.8% in education facilities. As education facilities damaged from Gyeong-ju, Po-hang earthquake occurred in South-Korea and the rate of earthquake-resistant is low, the seismic retrofit of existing education facilities got to be ordinary people's interest. Therefore, domestic researchers have been developed seismic retrofit methods which can apply to existing educational facilities, It is expected to become more active in the future. However, it is insufficient to consideration that how far domestic technology has been developed. Therefore, the objective of this study is to measure the level of domestic research through comparative analysis between domestic and foreign researches that seismic retrofit methods which can apply to existing educational facilities.