Recently, demand for construction aggregates is increasing due to the growth of construction site scale. As natural aggregate sources are becoming depleted due to high demand in construction field, the utilization of recycled aggregate (RA) as coarse aggregate in concrete is becoming more important. In this study, the authors analyze the mechanical properties of normal- and high-strength concrete beams using RA and investigate the usefulness of the minimum steal ratio for RA reinforced concrete beams. The experimental results show that application of the minimum steel ratio to RA reinforced concrete beams is possible.

단층비지는 단층의 중심부에 분포하면서 연약대를 형성하므로 단층비지의 광물학적 특성과 물성은 암반의 안정성에 크게 영향을 미친다. 본 연구에서는 단열구조도를 참고하여 중, 대규모의 주요 단층을 선정하였으며, 총 16지역의 단층 코어부분에서 51종류의 시료를 채취하였다. XRD, SEM을 이용한 광물학적 분석과 단위중량, 마찰각, 점착력을 측정하였다. 점토광물은 대표적으로 카올리나이트, 일라이트, 스멕타이트로 나눠질 수 있으며, 화산암에는 일라이트 > 스멕타이트 > 카올리나이트와 녹니석의 순으로 함유된다. 퇴적암에는 카올리나이트와 녹니석 > 일라이트 > 스멕타이트의 순으로 풍부하다. 화강암에는 일라이트 > 스멕타이트 > 카올리나이트와 녹니석 순으로 함유된다. 마찰각은 점토 함량이 높을수록 감소하며, 점착력은 분산이 심하게 나타났다. 점토광물의 함량이 45% 이하에서는 점토광물의 함량이 증가할수록 점착력이 높아지나 45% 이상에서는 점착력이 낮아지는 추세를 보인다. 이는 단층비지가 불균질하며, 점토광물의 종류와 함량에서도 넓은 범위를 가지기 때문인 것으로 보인다.

We have carried out the bridge inspections according to the laws not considering the technical knowledge. It is reasonable to optimize the inspection practice within the limited resources. This study reviews the expressway bridge inspection types, interval, scheme and so on

Current design standards (Korea Highway Bridge Design, AASHTO), the dynamic behavior under the impact loading has not been considered, only considered static force for designing bridge column against vehicle collisions. In this study, vehicle collisions to concrete bridge column were developed with various boundary conditions, and a comparison study of direct impact analysis of vehicle to bridge-column with in-direct impact analysis was performed.

Traditional demolition methods for maritime bedrock may not adequate specially for urban areas and historical places due to hazard of explosive and noise. Therefore, an use of soundless chemical demolition agent (SCDA) increased to reduce the noise and avoid from explosive methods. However, there is no guideline or design code for using SCDA. In this study, crack control for maritime bedrock demolition using SCDA is performed.

Recently, the use of high strength concrete is increasing in order to increase of high-rise building. High strength concrete has properties that are weak in fire. In severe case, buildings have risk of collapse owing to occur spalling. For these reasons, the authors think it is required to conduct various study about thermal and mechanical properties of high strength concrete in fire. This study analyze thermal and mechanical properties of high strength concrete at elevated temperature to use composite fibers mixed method which is one of method to prevent spalling.

The present study reviews bridge management index and bridge management system (BMS) in China, Japan, Korea, and U.S. In Korea, BMS should include functions enable to quantify the risks, safety, and optimization models of cost/benefit associated with bridges. There are similarities in bridge management index of four countries.

This paper aims at optimizing fire risk assessment for highway bridges using different classification schemes. Based on results, highway bridges are categorized into three groups according to fire risk levels and compared to actual cases of fire incidents. From comparisons, it is required to determine the proper classification scheme according to type of risk and data.

This paper presents the definition of bridge life and the end-of-life criterion of bridge for bridge maintenance purpose. Bridge life can refer to the period of time in which the bridge meets all desired levels of its functions maintained by maintenances. The end-of-life criterion of bridge can defined when a damage score of an entire bridge reach 0.64, the bridge is assumed to be end of life.

This study reviews past literatures relevant to concrete beams using recycled aggregates (RAs) and investigate existing shear design equations for reinforced concrete (RC) beams. Then, a simplified, emprical design equation to determine the shear strength of high strength RC beams with RAs is proposed and compared with existing equations. The analysis indicated that the proposed equation provided the most accurate estimated of strength of high strength concrete beams with RAs.

This study established key factors causing deck slab deterioration based on GPR database of 747 highway bridges, and predicted deck slab damage rates with respect to bridge service life. To minimize the influence of bridge service life on deck slab deterioration, the deck slab damage rate database was corrected based on a linear regression model of bridge service life vs. deck slab damage rate. The corrected deck slab damage rates were analyzed to determine correlation considering the number of snowy days, the amount of snowfalls, the number of freeze-thaw days, average winter temperature, altitude, the amount of deicing chemicals and equivalent traffic volume, and then both the number of freeze-thaw days and the amount of deicing chemicals were determined to be key factors causing deck slab deterioration. The complex deterioration considering both key factors was represented deck slab damage rate charts, and the average deck slab life was derived. The results of this study will be used as a guideline for highway bridge maintenance to identify the progress of deck slab deterioration for a given bridge and predict the time required deck slab rehabilitation.

The bridge is one of the important infrastructures. If vehicle collision is occurred in bridge column, It can caused for bridge collapse. Bridge columns are vulnerable to impact loadings of Vehicles. In this study, Non-linear dynamic analysis of reinforced concrete bridge column in impact loading were performed using LS-Dyna.

Hokenberry and Lopez (2012) and Aoude et al. (2012) have shown that the steel fiber can be a substitute of the stirrup for shear strengthening. In this study, Vector 2 program which takes into account modified compression field theory tensile softening behaviors of SFRC were used for prediction of the shear capacities of SFRC beams.

In this study, shear behaviors of various SFRC were predicted using Vector 2 program. Obtained analytical data was compared with preceded experimental data performed by other researchers. It was found that one increase in the span to depth ratio results in 54% decrease in the shear strength. Likewise, 1% increase in the reinforcement ratio causes a 19.9 % increase in the shear strength.

This paper conducted comparison of the bridge maintenance index of South Korea, China and USA. In this paper summarized that The agency who take the maintenance activity, maintenance manual and characteristic of the bridge maintenance index. Also, based on summary and comparison, this study proposed sugesstions for improvements of bridge maintenance index.

This study examined the collapse of bridge under extreme events. As a result, numerous bridges collapsed by scour, collision, fire and earthquake. The research team studied four cases of previous bridge collapse and restoration following extreme events. Finally, the disaster type factor were selected.

본 연구에서는 우선 화재에 노출된 고강도 콘크리트의 내화특성과 폭렬 메커니즘을 규명한 기존 국내외 연구자들의 연구문헌들을 심도 깊게 고찰하였다. 그 후 고온을 받은 고강도 콘크리트에 대한 국내외 연구자들의 주요 실험 변수를 분석하여 가장 최적의 변수를 설정하였으며 이를 토대로 하여 100MPa급 고강도 콘크리트의 내화 특성을 규명하기 위한 내화실험을 계획하였다. 또한 기존 연구의 실험결과를분석한 결과 폭렬방지에 효과가 있는 것으로 알려져 있는 PP섬유와 친수성 재료로서 시멘트 입자와 부착성능이 우수하고 워커빌리티를 개선할 수 있는 NY섬유를 혼합한 신재료 HB섬유를 섬유혼입률 0.05%로 정해 배합설계에 반영하였다. 이러한 배합설계로 타설한 총 48개의 공시체를 28일 양생기간 후 온도변화 (100℃~700℃)에 따른 고강도 콘크리트의 역학적 특성을 분석하기 위해 화재를 받은 후 냉간상태에서의 내화실험을 수행하였으며 이를 통해 고강도 콘크리트의 내화 특성을 분석하였다.

Suspension bridge, one of the long span bridge type, is vulnerable to wind load. To analysis effect of wind load, this paper peformed 2D analysis for suspension bridge. Numerical model is consisted suspension bridge cross section and two nonlinear hanger cable. Suspension bridge cross section has mass and torsional resistance. Nonlinear hanger cable stiffness is bigger as displacement larger. This paper compare w/ torsional resistance model and w/o torsional resistance model. Analysis results show that w/o consider cross section torsional resistance is likely to overestimate structure response.

Vehicle collision is one of cause for structural failure. The increased load carrying capacity of the truck is also a threat for existing structures. Recent studies show the actual shear capacity of the column of bridge is larger than industrial standards. In this study, truck-column collision model was developed and load carrying capacity of a column were evaluated.

In order to lengthen the integral abutment bridge (IAB), pile-to-pilecap performance is one of the most important parts of the bridge since IABs have no expansion joints. Therefore, this study intended to develop four new types of pile-to-pilecap connections to improve the IAB performance using numerical analysis. Developed connections allow larger displacement and successfully control the crack generations.