• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.453-456
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• 2004

RC frames built prior to the advent of the philosophy of ductile concrete is one type of existing construction susceptible to damage. Strengthening and stiffening of such frames has been accomplished by infilled frames with cast-in-place, reinforced concrete walls. Placement of CIP shear walls within strategic bays of a structure appears to be a logical and economical method to strengthen a reinforced concrete frame and to stiffen a building in order to reduce architectural and mechanical damage. This study investigates the seismic performance of cast-in place infilled shear wall within existing frames. The object of this study is to clarify the seismic capacity and characteristics in the hysteretic behavior of bare frame, CIP infilled shear wall and CIP infilled wall reinforced diagonal bars.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.53-56
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• 2008

A reinforced concrete (RC) cast-in-place (CIP) infill wall retrofitting method may provide an improved seismic performance and economical efficiency for the non-ductile rahmen structures. In this study, four one story-one bay non-ductile frame were constructed and retrofitted with CIP infill wall to evaluate seismic performance of CIP infill wall-frame. From the test results, infill wall-frame exhibited a marked increase in shear strength compared to non-ductile RC frame specimen. But the ductility and story-drift at maximum load were decreased when shear strength of infill wall larger than that of existing RC frame. Therefore, it is confirmed that adequate reinforcement detail is required to assure sufficient seismic performance.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.281-288
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• 1999

This paper studied the efficiency of retrofitting of reinforced concrete structure which was not designed to endure an earthquake. The earthquake in Kobe Japan showed that there was a great possibility of having an earthquake even in big city and the damages were concentrated on mid or low story buildings which were not considered to be protected from an earthquake, . This experiment used reinforced concrete structure which restrained side-by-side displacement to test durability against an earthquake. This study deals with the structural performance of reinforced concrete frame structures strengthened with steel materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.607-616
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• 2022

Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.611-622
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• 2008

Nonlinear analyses have been carried out for both bridge piers and a bridge structure being repaired using a repair element in order to assess the post-repair seismic response of such structures. For this purpose, a simplified CFRP stress-strain model has been proposed. The analytical predictions incorporating the current developments correlate reasonably well with experimental results in terms of strength and stiffness. In addition, nonlinear dynamaic analyses have also been conducted for a bridge structure in terms of the created multiple earthquake sets to evaluate the effect of pier repair on the response of a whole bridge structure. In these analyses, potential plastic hinge zones of piers are virtually repaired by CFRP and steel jacketing. Comparative results prove the virtual necessity of performing nonlinear post-repair analyses under multiple earthquakes, particularly when the post-repair response features are required. In all, the present approaches are expected to provide salient information regarding a healthy seismic repair intervention of a damaged strcuture.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.295-303
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• 2023

South Korea has recently witnessed an increasing number of seismic events, leading to a surge in studies focusing on seismic earth pressures, as well as the attributes of geological layers and ground where foundations are established. Consequently, earthquake-resistant design has become imperative to ensure the safety of subterranean structures. The slurry wall method, due to its superior wall rigidity, excellent water resistance, and minimal noise and vibration, is often employed in constructing high-rise buildings in urban areas. However, given the separation between panels that constitute the wall, slurry walls possess limited resistance to seismic loads in the longitudinal direction. As a solution, several studies have probed into the possibility of interconnecting slurry wall panels to augment their seismic performance. In this research, we developed and evaluated a method for linking slurry wall panels using mechanical joints, including concrete-confined steel pipes and headed bars, through mock-up tests. We also assessed the constructability of the suggested method and compared it with other analogous methods. Any challenges identified during the mock-up test were discussed to guide future research in resolving them. The results of this study aid in enhancing the seismic performance of slurry walls through the development of an interconnected panel method. Further research can build on these findings to address the identified issues and improve the efficacy and reliability of the proposed method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.18-28
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• 2015

The purpose of this study is to develop a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. The results were analyzed to find that the specimen with anchored connection experienced shear failure, while the other specimen with steel plate connection principally manifested flexural failure. The ultimate strength of the specimens was determined to be the weaker of the shear strength of top connection and flexural strength at the critical section of precast panel. In this setup of U-type panel specimens, if a push loading is applied to the reinforced concrete column on one side and push the precast concrete panel, a pull loading from upper shear connection is to be applied to the other side of the top shear connection of precast panel. Since the composite flexural behavior of the two members govern the total behavior during the push loading process, the ultimate horizontal resistance of this specimen was not directly influenced by shear strength at the top connection of precast panel. However, the RC column and PC wall panel member mainly exhibited non-composite behavior during the pull loading process. The ultimate horizontal resistance was directly influenced by the shear strength of top connection because the pull loading from the beam applied directly to the upper shear connection. The analytical result for the internal shear resistance at the connection pursuant to the anchor shear design of ACI 318M-11 Appendix-D, agreed with the experimental result based on the elastic analysis of Midas-Zen by using the largest loading from experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.86-93
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• 2020

The demand for maintenance in Korea infrastructure facilities constructed since the 1970s has increased significantly compared to the demand for new construction. Moreover, after the Gyeongju and Pohang earthquakes, seismic performance evaluation, repair, and retrofitting projects have been carried out. Therefore, in this study, a specimen was designed following the L-type GFRP Plate Externally Bonded Retrofit method, one among other retrofit methods. The L-type GFRP Plate was bonded to the specimen by epoxy and a washered steel nail. A four-point bending test was performed to confirm the strengthening effect of the Externally Bonded Retrofit method using an L-type GFRP Plate. The strengthening effect of the L-type GFRP plate was proven experimentally, and the behavior of the beam designed following the L-type GFRP Plate Externally Bonded Retrofit method was evaluated according to Korea's "Design Manual & Specification for Strengthening of RC Structures by Advanced Composites System". Furthermore, the effectiveness of the bonding method, a combination of epoxy and washered steel nail, was also checked. The results showed that the design, according to the guidelines mentioned above, predicted the strength of the member well, but the failure mode did not satisfy the design assumption because of unexpected damage to the GFRP plate due to the fixing method, washered steel nail.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.61-71
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• 2010

Five half-scale beam-to-column connections in a precast concrete frame were tested with cyclic loading that simulated earthquake-type motions. Five half -scale interior beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including one monolithic specimen and four precast specimens. Variables included the detailing used at the joint to achieve a structural continuity of the beam reinforcement, and the type of special reinforcement in the connection (whether ECC or transverse reinforcement). The specimen design followed the strong-column-weak-beam concept. The beam reinforcement was purposely designed and detailed to develop plastic hinges at the beam and to impose large inelastic shear force demands into the joint. The joint performance was evaluated on the basis of connection strength, stiffness, energy dissipation, and drift capacity. From the test results, the plastic hinges at the beam controlled the specimen failure. In general, the performance of the beam-to-column connections was satisfactory. The joint strength was 1.15 times of that expected for monolithic reinforced concrete construction. The specimen behavior was ductile due to tensile deformability by ECC and the yielding steel plate, while the strength was nearly constant up to a drift of 3.5 percent.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.741-751
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• 2010

An experimental study was performed to investigate the earthquake resistance of the beam-column connections as a part of a precast concrete moment-resisting frame that uses precast concrete U-shaped shells for the beams. Five full-scale precast concrete specimens and one conventional monolithic concrete specimen were tested under cyclic loading. The parameters for this test were the reinforcement ratio, stirrup spacing, and end-strengthening details of the precast beam shell. The test results showed that regardless of the test parameters, the precast concrete beam-column connections showed good load-carrying capacity and deformation capacity, which were comparable to those of conventional monolithic concrete specimen. However, at large deformations, the beam-column connections of the precast concrete specimens were subjected to severe strength degradation due to diagonal shear cracks and the bond-slip of re-bars at the joint region. For this reason, the energy dissipation capacity and stiffness of the precast concrete specimens were significantly less than those of the cast-in-place specimen.