• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.157-157
• /
• 2011

프리캐스트 콘크리트 박스 암거는 현장 타설식 암거에 비해 구조물의 고품질화 및 반복적인 대량생산으로 원가 절감과 건식화 시공으로 인한 공정의 단순화와 공기가 단축되는 이점을 지니고 있다. 따라서 본 연구는 상재 허용하중을 확보하고, 시공성 및 내구성이 뛰어나며, 경제성을 고려한 고성능 프리캐스트 박스 암거를 개발하고 향후 고성능 프리캐스트 박스 암거를 생산하기 위한 기초적인 자료를 제시하고자 하였다. 본 연구에서는 기존의 보통 포틀랜드 시멘트를 이용한 프리캐스트 박스 암거의 경제성 및 내구성, 강도특성을 개선하고자 고로슬래그를 이용하여 최적의 배합비를 산출하고, 이를 토대로 중성화, 염해, 동결융해 등의 시험을 통해 내구성을 확보하고, 휨 성능을 확인하고자 실물박스암거를 제작하여 외압강도시험을 실시하였다. 또한 구조해석을 통해 응력검토를 하였다. 내구성 검토 결과, 분말도 $6,000cm^2/g$을 가진 고로슬래그 미분말을 50%로 혼입한 콘크리트가 보통 포틀랜드 시멘트를 사용한 콘크리트보다 염화물이온 투과성에 대한 저항성 및 동결융해 저항성 등 기초물성 및 내구성이 개선됨을 알 수 있었다. 박스암거에 대한 휨 시험 결과, OPC에 비해 GFSC6의 경우는 크게 구조적 성능이 떨어지지는 않는 것으로 나타났으며, 균열양상 및 연성도에서는 우수함을 나타냈다. ABAQUS에 의한 비선형 해석 결과는 시험체의 휨 거동을 잘 묘사하는 것으로 나타났으며, 처짐의 경우 시험체의 시험결과보다 크게 나타났지만, 처짐 양상은 비슷한 것을 알 수 있었고, 벽체와 상부 슬래브에 발생하는 응력은 부재가 허용하는 균열응력값 이내로 나타남에 따라 사용하중 상태에서의 응력검토는 안전한 것으로 판단된다.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.107-116
• /
• 2000

Dynamic and static load tests are conducted in four construction sites by using steel pipe piles(SPP) and concrete piles to compare differences of load bearing mechanism. Steel pipe piles are instrumented with electric strain gages and are subject to dynamic load tests during driving. The damage of strain gages attached is checked simultaneously. Static load test is also conducted on the same piles after two to seven days' elapse. Then load-settlement behavior and shaft and/or tip resistances are measured. As a result, the allowable bearing capacity calculated by the Davisson's offset method of CAPWAP analysis shows 2~33% larger than that of static load test. The average value of allowable bearing capacity of static load test is closer to the allowable capacity obtained at the safety factor of 2.5 applied on ultimate bearing capacity than to the one obtained from the Davisson's offset method. The analysis of strain gage readings shows that unit skin friction increases with depth. Furthermore, the friction mobilized around the 1~2m above the pile tip considerably contributes to the total shaft resistance.

• Korean Journal of Construction Engineering and Management
• /
• v.12 no.5
• /
• pp.46-54
• /
• 2011

There have been research and developments for effective and efficient logistics and progress management in a construction project. Among them, RFID+4D has been developed for the supply chain management of long-lead item materials such as steel component, precast concrete component and curtain wall by integrating RFID with 4D CAD. And the feasibility of RFID+4D has been verified and validated and the benefits in terms of time and cost were shown in several case studies. However, the previous development of RFID+4D has not been adapted widely because of additional modeling cost, non-real time data update, additional labor for data update, and so forth. Therefore, this research has proposed a framework and process for solving these problems. And the web based simulation system has been developed and verified based on the proposed framework. The proposed framework and process can improve the existing RFID+4D system in a construction project by saving its operation cost and utilizing project information more efficiently and effectively. Also it is expected that the proposed framework could be applied to a method transferring design RIM data to construction BIM data.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.541-544
• /
• 2001

PC Box Girder was constructed by PSM(Precast Span Method) to solve the shortage of the construction period. The site case study was used in the PSM to find the construction productivity improvement. In this case study, main reasons of low productivity were founded unskilled technical engineers and insufficient equipment management winter season concrete curing condition. Productivity improvements are presented by assigning production personnel appropriately, motivation which increased by providing incentives for technical engineers, strictly cooperation of each participant, organizational teamwork, and Promoting productive work condition. Additional method of productivity improvements are continuous improvement of the work methods by considering the feedback on previous work, and continuous training to best handle the site conditions. This study of productivity improvement will help to use the most advantage of the PSM method and desire to successfully plan the future construction performance.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.13 no.2
• /
• pp.189-196
• /
• 2000

The objective of this paper is to propose an analysis technique to predict the behavior of PC wall structures subjected to cyclic load. While PC wall panel is idealized by finite elements, the joints at which PC walls are connected each other are idealized by nonlinear spring elements. Axial and shear spring elements are developed for simulating shear, compression and tension behaviors of joints. The strength and stiffness of each spring elements we presented from the previous research results and incorporated into the computer program of DRAIN-2DX. The proposed analysis technique is evaluated by analyzing specimens previously tested and comparing with those. On the strength, stiffness, energy dissipation and lateral drift, analytical results show good agreements with test results. This means the proposed technique is effective to predict the response of the PC wall structures.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.2
• /
• pp.165-171
• /
• 2016

The objective of this study is to evaluate the compressive strength development and ecological characteristics of mortars using expanded vermiculite absorbing bacteria as a fundamental investigation to develop precast eco-concrete products. For bacterial growth under the high-alkalinity and high-dried environments within hardened mortars and for creating plant growth function to mortars, Bacillus alcalophilus and Rhodoblastus acidophilus were separated and cultured. The cultured bacteria were absorbed into expanded vermiculite selected for bacteria shelter. The expanded vermiculite absorbing bacteria was then added into mortar mixture as a volumetric replacement of fine aggregate. Test results showed that the developed technology is very effective in enhancing the plant growth onto the hardened mortars and reducing the COD and T-N concentration in raw water. The optimum replacement level of expanded vermiculite absorbing bacteria can be recommended to be less than 10% considering the compressive strength development and cost of mortars along with the ecological effectiveness.

• Korean Journal of Construction Engineering and Management
• /
• v.15 no.4
• /
• pp.20-29
• /
• 2014

As construction projects increase their complexity, variety, and scale, various recognition applications (such as RFID, bar-code etc.) have been tried for managing material effectively in construction projects. However, existing recognition applications for construction material management have some limitations that cause additional works (such as attaching RFID tag), additional cost (labor cost, recognition device cost, etc.), and cognitive impairment of workers. Therefore, this study proposed a character recognition technology as an alternative of previous recognition technologies such as RFID, bar-code, etc. The technical feasibility of proposed technology was validated by three recognition tests. Additionally, this study proposed code the structure to manage materials using the character recognition technology. The effects of character recognition technology are presented by comparing with existing RFID-based logistics processes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7244-7249
• /
• 2015

In this study, in order to asses the structural performance of trapezoidal PSC girder using a socket joint system and it is possible to calculate the optimized cross-section of the web element tests were carried out for each specimens. we conducted a socket joint performance test, web bending and shear performance tests and all tests were performed at 4 point loading method. The initial crack load of socket joint specimen was significantly lower than the reference specimen but post peak behavior was no significant differences. And the length of the loop joint of the reinforcing bars had no significant effect on the maximum load. As a web shear tests, to obtain a maximum load of the specimen has a prestressing rod reinforced at tension side. As a web flexural tests, to obtain higher diagonal cracking load in specimen of reinforced using prestressing rod than reference specimen.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.742-752
• /
• 2017

The bridge type of steel concrete composite rahmen or pre-flex has been applied where a lower depth girder is required due to vertical clearance restrictions caused by the crossing of rivers and roads. On the other hand, because these types are not only complicated to manufacture and construct, but also expensive, void slab bridges may be an alternative. In this study, prefabricated PSC-I shape girder was used to make a void slab and all procedures for bridge development, such as analysis, design, fabrication, and real-scale test, were included in the scope of research. The results of this study will provide sufficient background data to be applied to the field and the structural safety has been verified through experiments.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.9
• /
• pp.19-27
• /
• 2009

In order to investigate anti-freeze process of precast concrete L-type retaining walls in cold regions, test walls were installed in the campus of Kitami Institute of Technology (KIT, Hokkaido, Japan). The wall consists of following three sections, i) back filled with frost susceptible clay soil, ii) using thermal insulation material, and back filled with frost susceptible soil, iii) back filled with frost-unsusceptible soil. The freezing front distribution and ground temperature within the backfill were observed and deflections of the walls were measured over three freeze-thaw seasons. Some understanding of the mechanisms of the build-up of frost heave pressure was gained, and the effectiveness of replacement method was observed. A simulation was performed to predict the shape of the freezing front in the backfill behind L-type walls with various cross sections. These findings were employed to propose a method for determining the appropriate zone to be replaced with frost unsusceptible backfill material in cold regions.