In this study, a new strengthening alternative for RC structures, namely wing type steel frames, has been experimentally investigated under reversed cyclic loading. It has been observed that the usage of wing type steel frames considerably improve the capacity and sway stiffness of RC structures.

In this study, the behavior of column rebar in non-reinforced specimens (BF) was evaluated as part of the development of seismic retrofitting systems for public buildings such as school buildings. This is a very useful work because it can show the deformation state of the main bars according to the hysteretic behavior of lateral loads. When yielding the specimen, the main bar was yielded. and the deformation of stirrup at the inflection point position hardly occurred. These results will be used as a key index to evaluate the yield state of the structure from the deformation comparison of the reinforced specimens.

Multi-objective optimization coupled with GA-ANN Metamodeling Method and NSGAⅡ was implemented to optimize TMD installed on 10 story structure under El Centro earthquake. Layer number and nodes of ANN were optimized by use of genetic algorithm and NSGA-Ⅱalgorithm was applied to solve multi-objective optimization problem prepared by GA-ANN metamodel. It is found that the GA-ANN multi-objective optimized damper improved frequency responses and root mean square displacements of the structure without TMD by 34.7% and 76.4% under El Centro earthquake, respectively.

Multi-objective optimization using response surface methodology-based surrogate model was employed to find optimal design parameter of TMD installed on structure under the El Centro earthquake. It is found that the RSM based weighted multi-objective optimized damper improves frequency responses and root mean square displacements of the structure without TMD by 31.6% and 82.3% under El Centro earthquake, respectively, and has an equal or higher performance than the conventionally designed dampers with respect to frequency responses and root mean square displacements and when applied to earthquakes.

Numerical behavior of reinforced concrete(RC) column with GFRP seismic reinforcement was evaluated through the finite element analysis in this study. For the numerical analysis, a experimental test results was used to develop a nonlinear three dimensional finite element model of RC column with GFRP seismic reinforcement. The developed the nonlinear three dimensional finite element model of RC column with GFRP seismic reinforcement was well predicted the behavior, maximum strength and initial stiffness, of RC column with GFRP seismic reinforcement.

This research is an application of SHCC (Strain harding Cementitious Composite) in concrete shear wall system in order to improve the structural performance of conventional shear walls. Based on experimental loading results, it was observed that the developed SHCC shear walls showed improved strength as well as enhancements in controlling of bending and shear cracks.

This study investigates overseas and domestic practical applications of systems that combine seismic isolating characteristics and vertical vibration-proof function for releasing annoying vibration from road traffic, subways, and trains. This paper proposes the configuration of vertical vibration -proof and seismic isolating systems based on the evaluation of their effectiveness.

Nonlinear dynamic analysis of Non-seismic Designed subway station was verified with Channel Beam Damper system which was developed in former research. As a result of nonlinear dynamic analysis, column and beam are on LS(Life Safety) level by retrofitting with Channel Beam Damper system. The effect of Channel Beam Damper System was confirmed.

This study summarizes the results of the research results published by the researchers after the 2016 Gyeongju earthquake and will be reflected in the development of the seismic control system to be conducted in the future. Although various researchers' seismic analysis and effective frequency analysis for Gyeongju earthquake have been proposed, it is necessary to present the certified seismic records to evaluate the proper seismic response of the structure.

The paper introduce the experimental program of investigation on the performance of RC beams strengthened with Uni-Directional Narrow Fabric. A total of twelve shear-critical specimens were constructed and experimentally investigated through static loading tests. Experimental parameters include the shear rebar, the type of fiber, and spacing of the fiber. Testing data were analyzed to investigate the performance of the specimens retrofitted or strengthened with Uni-Directional Narrow Fabric compared to the behavior of the non-retrofitted RC beam.

This study was evaluated dynamic impact tensile properties of 80 MPa sprayed HPFRCC by I-SEFIM test as a part of the research for development of sprayed HPFRCC for protection and blast resistant of existing structures.

The techniques for seismic design and seismic reinforcement of structural members in Korea have beendeveloped in a wide variety of ways, but research and technology on seismic retrofitting methods of nonstructural materials are very inadequate. In this study, we analyze ceiling system products of Japan which have seismic performance as a basic study on the development of non-structural ceiling system.

This study aims to establish design and construction procedure in the fields of the repair and rehabilitation for existing concrete structures. The codes used in this study are ISO 16311 and ACI 562-16. The ISO 16311 and ACI 562-16 focused on maintenance and repair, respectively. After, we will make to design and construction guidelines to meet the domestic situation through analysis the repair and rehabilitation parts of the codes in detail.

Most apartment houses have been constructed with concrete structures. However, underground parking lots and rooftops in apartment buildings frequently have cracks due to drying shrinkage and various degradation factors. The leakage caused by this cracks has a problem that the durability of the structure and the waterproof performance is deteriorated. Therefore, the development of a proper crack repairing materials is continuously required. The purpose of this study is to apply chemically bonded ceramics (CBC) as a repair material to repair cracks in concrete, which has strong adhesion, durability, rapid hardening performance. Therefore, it was applied to the roof crack of the apartment(mock-up test) and the performance was evaluated. As a result, the compressive strength and the bond strength showed excellent performance. In the case of the dry shrinkage characteristics, the performance was stable in the range of -35 to 43 × 10 -6 until 20 days of age. In addition, the mock-up test results showed good workability and surface condition, and surface polishing is possible after 2 hours of consruction, which is considered to be very effective for Reducing work time.

In this paper, internal thermal stresses of the cementitious matrix were evaluated by incorporating polypropylene fibers. By using the temperature heating method specified in KS F 2257-1, the temperatures by a depth were measured. Thermal stress was calculated based on Kodur's thermal stress formula. Different thermal stress behaviors were observed depending on amount of PP fiber. Thas, it will become fundamental data to analyze the thermal stresses behavior of structure members subjected to higher temperature.

Externally post-tensioning steel rods led to a 25~66% increase of load-carrying shear capacity in damaged reinforced concrete beams when compared to a control beam. And the shear strength of a beam with two deviators was larger than that of a beam with one deviator. That shows how important a deviator location is for strengthening effect.

To examine the practical potentials of V-ties to provide a confinement to a strengthening jacket section of existing reinforced concrete members, direct bond tests were conducted under a parameter of the V-tie details. Test results showed that V-ties with headed-end had a higher bond strength than those with the other details.

After the application of the formuar for the reinforcement index to the behavior of the UHPFRC box girders, reinforcement index does not determine the characteristic of behavior of UHPFRC box girder exactly. So the index should consider the dimension precisely and reference value corresponding to the 0.005 strain of the prestressing strands.

The load-deflection curve and neutral axis changing curve, which were drawn by data from tests were analyzed. Both of steel fiber and reinforcing bar habe effect to induce the behavior of segmental U-shaped girder. The combination of 0.7% or 1.0% steel fiber and reinforcing bar sowed the effective ductle behavior of segmental U-shaped girder. The relationship of load-deflection and the crack pattern indicate that the appropriate combination are UFS1.0 and CFS1.0

The purpose of this study is determining the effects of flexural behavior of aramid fibers in ultra high performance concrete. The 10 kinds of aramid fibers with different length, diameter and twisting were used. The flexural behavior was determined by bending tests on specimens, which was prepared by mixing 1 % of volume fractions of aramid fibers into ultra high performance concrete mortar. Consequently, the load-displacement relationship curves were obtained by using the test results for each kinds of aramid. While the specimen that contains the small diameter of aramid fiber gives the strong flexural strength due to large contact area between the fiber and concrete matrix, that specimen by small diameter of aramid fiber does not guarantee the ductile behavior of specimen like the steel fiber. But the length and twisting of aramid fiber gives the ductile behavior of ultra high performance concrete flexural specimen.