In this study, the SBC system, a new mechanical joint method, was developed to improve the constructability of precast concrete (PC) beam-column connections. The reliability of the finite element analysis model was verified through the comparison of experimental results and FEM analysis results. Recently, the intermediate moment frame, a seismic force resistance system, has served as a ramen structure that resists seismic force through beams and columns and has few load-bearing walls, so it is increasingly being applied to PC warehouses and PC factories with high loads and long spans. However, looking at the existing PC beam-column anchorage details, the wire, strand, and lower main bar are overlapped with the anchorage rebar at the end, so they do not satisfy the joint and anchorage requirements for reinforcing bars (KDS 41 17 00 9.3). Therefore, a mechanical joint method (SBC) was developed to meet the relevant standards and improve constructability. Tensile and bending experiments were conducted to examine structural performance, and a finite element analysis model was created. The load-displacement curve and failure pattern confirmed that both the experimental and analysis results were similar, and it was verified that a reliable finite element analysis model was built. In addition, bending tests showed that the larger the thickness of the bolt joint surface of the SBC, the better its structural performance. It was also determined that the system could improve energy dissipation ability and ductility through buckling and yielding occurring in the SBC.

The paper presents the experimental investigation of RC beams retrofitted with Textile Reinforced Mortar (TRM), featuring enhanced bond capacity. Anchoring systems, including an extension of retrofitting length and the use of chemical anchors, are newly employed to improve the structural performance of the RC beam retrofitted with TRM. For the experimental investigation, a total of seven shear-critical RC beams, with and without stirrups, were designed and constructed. The structural behaviors of specimens retrofitted with the proposed TRM methods were compared to those of non-retrofitted specimens or specimens strengthened with conventional TRM methods. Crack pattern, force-displacement relationship, and absorbed energy were evaluated for each specimen. The experimental results indicate a significant improvement in the shear capacity of the RC beam with the proposed retrofitting method. Therefore, it is concluded that the application of an extended retrofitting length and chemical anchors to the TRM retrofitting method can effectively enhance the bond capacity of TRM, thereby improving the shear performance of RC beams.

The paper introduces an experimental program for the newly developed vertical joints between Precast Concrete (PC) walls to improve their in-plane shear capacity. Compared to the existing vertical joints, two types of vertical joints were developed by increasing the transverse reinforcement ratio and improving frictional force at the joint interface. A total of four specimens including the Reinforced Concrete (RC) wall and PC walls with developed vertical joints were designed and constructed. The constructed specimens were experimentally investigated through monotonic shear tests. The observed damage, load-deformation relationship, strain and strength are investigated and compared with the cases of RC wall specimen. Experimental results indicate that the maximum force and initial stiffness of the PC wall with proposed vertical joints were decreased by comparing with those of RC wall. However, the ultimate displacement increased by up to 217.30% compared to the RC wall specimen. In addition, brittle failure did not occurred and relatively few cracks and damages occurred.

Generally the non-bearing walls in apartment buildings in Korea are not considered as a lateral force resisting members for the design consideration. This engineering practice caused large crack damages and brittle fractures of the non-bearing walls when subjected to Pohang earthquakes in 2017 since those have not been designed for seismic loading. In this study, finite element analysis was conducted for slot type non-bearing wall connection system to reduce damages and concentrate damages to the designated damping device through separation from the structural wall members. Steel plate and dowel bar systems designed for the dissipation of seismic energies were modeled and analyzed to investigate the damage reductions. Finally, the test result and the analysis result were compared and verified.

This study introduces a newly developed PC non-bearing wall system to prevent the damage of RC wall-type apartments that have been heavily damaged by the 2017 Pohang Earthquake. In order to evaluate the performance of the developed PC non-bearing wall system, a static cyclic test is conducted. The prototype of test specimen is from the RC wall-type apartment which has been severely damaged by the 2017 Pohang Earthquake. The specimen with the conventional non-bearing wall system showed the similar damage of RC wall type apartment suffered from the Pohang Earthquake. In case of the specimen with the developed PC non-bearing wall system, cracks and damages were not transmitted between the walls due to the seismic slit and there were almost no cracks in the non-bearing walls. Therefore, the proposed non-bearing wall system, separated from the structural walls, could prevent spreading cracks to bearing walls and make it possible to effectively control damage due to earthquake loads.

경량화 설계 및 자유로운 성형이 가능하고 유사연성의 장점을 가지는 직물보강 콘크리트는 철근콘크리트의 대체재로 큰 기대를 모으고 있다. 본 연구에서는 탄소 직물을 보강한 콘크리트 복합체 (TRC) 패널의 휨 특성을 살펴보고, 탄소 직물의 배치 위치 변수에 따른 차이를 살펴보기 위해 TRC 시험체를 제작하고 4점 재하 휨실험을 수행하였다. 또한, 일반 철근콘크리트 개념을 바탕으로 시험체의 휨 거동을 수치계산 결과와 실험결과를 비교하였다. 실험 결과, 콘크리트 매트릭스에서 탄소 직물간 의 부착파괴로 인해 TRC 패널의 큰 휨강도 감소와 내하력 감소가 나타났고, 탄소 직물을 시험체 하부로 편심 배치한 경우 휨 성능의 감소를 다소 줄일 수 있었다. TRC 패널의 수치계산 결과, 초기 거동에서는 휨실험 결과와 유사한 거동을 나타내었지만, 두 번째 균열의 발생 이후부터는 부착파괴의 발생으로 거동의 큰 차이를 나타내었다.

본 논문에서는 아라미드 스트립을 이용하여 영구거푸집을 제작하고 철근 콘크리트 기둥에 적용하여 성능을 평가하였다. 보강된 철근콘크리트 기둥의 구조거동을 평가하기 위하여 총 3개의 기둥을 제작하였다. 1개의 실험체는 무보강 실험체로서 비내진 상세의 기둥이며 다른 두 실험체의 경우 내진설계가 적용되거나 아라미드 섬유보강 영구거푸집으로 보강하였다. 기둥의 전형적인 성능평가를 위하여 일정한 축하중하에서 정적반복가력 실험을 수행하였다. 실험결과 무보강 실험체와 비교하여 전단 강도, 연성 및 에너지 소산능력을 증가시켰으며 반복하중으로 인한 강도 및 강성 저감에서 우수한 성능을 보였다. 따라서, 본 연구에서 제안한 아라미드 보강 영구거푸집은 기존 RC 기둥의 내진성능을 향상시킬 수 있을 것으로 판단된다.

The paper presents the damage estimation of bridge structures in Daegu city based on the scenario-based earthquakes. Since the fragility curves for domestic bridge strucures are limited, the Hazus methodology is employed to derive the fragility curves and estimate the damage. A total of four earthuquake scenarios near Daegu city are assumed and structure damage is investigated for 81 bridge structures. The seismic fragility function and damage level of each bridge had adopted from the analytical method in HAZUS and then, the damage probability using seismic fragility function for each bridge was evaluated. It was concluded that the seismic damage to bridges was higher when the magnitude of the earthquake was large or nearer to the epicenter.

현대 섬유 기술의 발전으로 박리에 의한 복합체 파괴 가능성을 줄일 수 있고, 복합체의 전단강도를 향상시킬 수 있는 있는 3차원 직물섬유를 제작할 수 있게 되었다. 본 연구에서는 3D 직물섬유의 시멘트 기반 복합체 적용 가능성을 살펴보기 위해 3D 직물섬유의 종류, 매트릭스의 종류, 보 부재 높이를 변수로 한 3D 직물섬유 보강 모르타르 보 시험체를 제작하고 휨실험을 수행하였다. 휨실험 결과, 3D 직물섬유 보강 모르타르 부재는 전형적인 직물섬유 보강 콘크리트의 휨거동과 유사한 결과를 나타내었다. 3D 직물섬유 보강을 통해 보 부재의 휨강성 및 휨인성이 향상되었고, 6mm 스페이서를 가진 직물섬유 보강 시험체가 4mm 스페이서를 가진 직물섬유 보강 시험체 보다 더 높은 휨강도 및 휨인성을 보였다. 3D 직물섬유 보강 모르타르의 휨강도 및 휨인성을 보다 향상시키기 위해서는 높은 인장강도와 탄성계수를 가지는 섬유의 적용, 섬유량의 증가, 인장단에 가까운 섬유의 배치가 필요하다.

The paper presents an experimental study on shear behavior of RC beams retrofitted with Uni-Directional Narrow Fabric to improve seismic performance. Experimental parameters include the type of fiber, spacing of the fiber, and the ratio of transverse reinforcement. Also, Static loading test was performed on twelve shear-critical specimens. An experimental result were analyzed to investigate the contribution of shear strength and failure modes of the specimens retrofitted or strengthened with Uni-Directional Narrow Fabric compared to the non-retrofitted the specimen. In order to derive the shear strength model according to the spacing of the fiber, the experimental results were compared with the conventional shear strength model of RC elements retrofitted with FRP.

The paper presents an experimental evaluation of RC columns retrofitted by TRC(Textile fabric Reinforced Concrete). TRC were made using textile fabric fiber and self leveling mortar. A total of three specimens was constructed and was performed cyclic loading test. One specimen was a non-retrofitted column, while others were retrofitted with textile fabric and sheet type fiber. By comparing with non-retrofitted specimen, the maximum strength and ductility of retrofitted RC column was improved compared to non-retrofitted RC column.

Observations of the damages to high-rise reinforced concrete (RC) wall building structures caused by by recent earthquakes in Chile (Mw 8.8, February 2010) and New Zealand (February 2011, ML 6.3) have generally exceeded expectations. Firstly, this study estimated the seismic damage levels of 15-story RC box-type wall building structures using the analytical models calibrated by the results of a shaking table test on a 1:5 scale 10-story RC box-type wall building model. Then, the seismic fragility analysis of the prototype model was conducted by using the SAC/FEMA method and the incremental dynamic analysis (IDA). To compensate for the uncertainties and variability of ground motion and its impacts on the prototype model, in the SAC/FEMA method, a total of 61 ground motion records were selected from 20 earthquakes, with a magnitude ranging from 5.9 to 8.8 and an epicentral distance ranging from 5 to 105km. In the IDA, a total of 11 ground motion records were used based on the uniform hazard response spectrum representing a return period of 2,475 years. As a result, the probabilities that the limits of the serviceability, damage control, and collapse prevention would be exceeded were as follows: from the SAC/FEMA method: 79%, 0.3%, and 0%, respectively; and from the IDA: 57%, 1.7%, and 0%, respectively.

This paper presents an experimetal study on RC beam strengthened with 3D Ultra-High-Mocular-Weight-Polyethylene (UHMWPE) fabric. This research program aims at developing the 3D UHMWPE textile fabic to improve the structural performance of RC beam. Specimens were constructed and experimentally investigated through static tests. Testing data were analyzed to investigate the performance of the specimens retrofitted or strengthened with UHMWPE fiber compared to the non-retrofitted RC beam responses. It was concluded that the strengthening method using 3D UHMWPE fiber can improve the performance of RC beam.

This paper briefly introduces the design seismic loads in Korea (KBC 2009). Then, over 10,000 recorded earthquake ground accelerograms, with their magnitude ranging from 4.0 to 8.0 and their epicentral distance ranging from 0 to 200 km, were used to examine the appropriateness of seismic load defined in Korea known as a low-to-moderate seismicity region. The following conclusions are drawn based on the results: (1) The effective peak ground accelerations (EPA) of recorded earthquake accelerograms under M ≤ 6.0 and R ≥15 km appear to be less than that of MCE in Korea for all site conditions defined in KBC 2009. (2) The design spectrum (two-thirds of the intensity of MCE) in KBC 2009 is comparable to those of earthquake records in the magnitude 6 - 7 and the epicentral distance less than 50 km. Therefore, (3) the intensity of Korean design earthquake is considered to be overly high since the Korea peninsula is generally conceived to be a low-seismicity region.

This study presents an experimental study on compressive and flexural strengths of concrete reinforced by 3D Fiber Reinforced Polymer(FRP). This study is intended to investigate the potential of 3D FRP concrete composites against impact or explosive loadings. For the comparative study, non-reinforced specimen and specimens reinforced by 3D FRP are constructed and tested. 20mm×10mm 3D fiber and 25mm×20mm 3D fiber was set to be variable.

This paper experimentally investigates the seismic performance of RC columns retrofitted by Super Reinforcement with Flexibility (SRF). A total of three specimens with a scale factor of 1/2 were constructed and tested in order to assess the structural behavior of the retrofitted RC columns. One specimen was a non-seismically designed column without any retrofitting method while others were retrofitted with either one or two layers of SRF by using urethane adhesive. The static cyclic testing with a constant axial load was conducted to assess the seismic performance of the retrofitted RC columns. It is concluded that the SRF retrofitting method increases the strength and ductility of the RC columns and can also impact on the failure mode of the columns.