• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.517-528
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• 2013

The modular technology has been already applied in automotive industry, plant and shipbuilding industry. Recently, the modular technology was applied in bridge construction. The modular bridge is different from the existing precast bridges in terms of standardized design that the detailed design of members is omitted by using the standard modules; the design of the modular bridge is completed by only assembling the standard modules without design in member level. The girder-type precast modular bridge has been developed as a simply supported bridge. The girder-type precast modular bridge could be applied to the multi-span bridges through the continuity method. The continuity of the girder-type precast modular bridge is achieved by using the link slab which is easy to construction and appropriate to the rapid construction. The link slabs have been used as the type of reinforced concrete structure in US from the 1950's. In 2000's, the link slab using the engineered cementitious concrete (ECC link slab) has been developed. In this study, the RC type link slab which is more reproducible and economic relative to the ECC link slab was used for the continuity of the girder-type precast modular bridges, and the construction detail of RC type link slab was modified. In addition, the modified iterative design method of RC type link slab was proposed in this study. To verify the proposed design method, the flexural tests were conducted using the RC type link slab specimens. Also, the fatigue test using the mock-up specimen was conducted with cyclic loading condition up to two million cycles.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.165-174
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• 2010

This study was conducted to evaluate the feasibility of expedite repairing of concrete pavements using precast concrete pavement method and to investigate the effectiveness of slab connection methods. In the demonstration construction, four slabs of jointed concrete pavements were replaced with the precast slabs. First, precast concrete slabs were designed and fabricated, then existing slabs were cut and removed, and finally precast slabs were installed. The slabs were leveled and pockets, holes, and space between the slab bottom and the underlying layer were grouted. From the demonstration construction, details about the design and construction of the precast pavements for repairing of pavements were evaluated. In addition, the slab connection methods such as pocket and hole connection methods were applied in the construction and the slab curling behaviors at the joints that include those connection methods were compared. The results showed that both slab connection methods were applicable, and the hole connection method was superior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.94-101
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• 2010

Recently, the interest of precast concrete is increased for rapid construction in construction fields. Experimental study about the shear performance of the joint between hollow core slabs which have internal core to reduce their weight was performed. Main test variables were thickness of the topping concrete and existence of the wiremesh. Total 8 specimens including 4 in-plane shear and 4 out of plane shear were tested. Test results were analyzed in terms of cracking load, failure load, failure aspect, stiffness and ductility, and compared its design load to develop optimum design details. Test results indicated that the shear performance of the non-shrinkage mortar specimen was similar to that of 30mm thickness topping concrete specimen, and the effect of wiremesh reinforcement did not affect the failure load or stiffness of the specimens but the increase of ductility. And this paper presents the comparison results of the test results and design load to provide the optimum detail of the joint design between the hollow core slabs.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.305-308
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• 2008

This paper presents the results of an experimental study carried out Prestressed Concrete Slab System of WAffle Shape(WAS), was perfomed in order to inverstigate it connection shear behavior according to primary paramaters: connection interval, filling matarial. Specimen is produced in Precast Concrete factories and it comprised one WAS panel and two half WAS panels and then it is filled with packing. Within the ranges of the parameters of the connection details used in this test, connections can develop greater shear strength than the nominal shear strength and the design service load for parking structures.

• Magazine of the Korea Concrete Institute
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• v.27 no.5
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• pp.36-39
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• 2015

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.80-86
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• 2020

In the fabrication process of inverted multi-tee (IMT) slabs, concrete has to be poured twice due to its shape, which is a huge disadvantage as a precast member. To overcome this, a new technique for manufacturing IMT slabs using a slipform method has been recently developed. In this study, flexural and shear tests were carried out to investigate the structural performances of inverted multi-tee (IMT) slabs manufactured using slipform method. To this end, one flexural specimen and two shear specimens with topping concrete were fabricated, and their failure modes and crack patterns, and the slips that occurred between the precast slab and topping concrete were measured and analyzed in detail. In addition, the flexural and shear strengths of the specimens were evaluated by utilizing the structural design code, and a shear strength estimation method, which is suitable for composite IMT slabs with different concrete properties, was proposed for practical design. The IMT slab satisfied the nominal flexural strength calculated by the current design code, and the proposed method provided a good estimation of the shear strength of the specimens.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.391-398
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• 2010

The fire performance of RC slabs with half-depth precast panel after exposure to the ISO-834 fire standard without loading has been experimentally investigated. During heating, according to the ISO 834 fire curve, concrete spalling was observed for concrete without PP(polypropylene) fibers. No spalling occurred when heating concrete containing PP fibers. The maximum temperature of RC slabs with PP fibers with half-depth precast panel was lower than that of concrete without PP fibers. The ultimate load after cooling of the RC slabs that were not loaded during the furnace tests was evaluated by means of 3 points bending tests. The ultimate load of the RC slabs without PP fibers showed a considerable reduction (around 32.5%) of the ultimate load after cooling if compared with of RC slabs with PP fibers. The ultimate load of the RC slabs with half-depth precast panel with PP fibers is higher than that of a full-depth RC slabs with PP fibers. Also, the addition of PP fibers and the use of half-depth precast panel improve fire resistance.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.157-157
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• 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 Korea Concrete Institute
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• v.27 no.2
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• pp.137-145
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• 2015

The slab-type precast modular bridge consists of the precast slab bridge modules which are connected in the transverse direction. The longitudinal joints between the precast slab bridge modules are filled with cast-in-place mortar. The construction of the slab-type precast modular bridge is completed by applying the prestressing force on the longitudinal joints. In this study, 4-points bending tests and 3-points bending tests were conducted to examine the effects of the prestressing force and the shape of joint on the flexural strength and crack serviceability of longitudinal joint. The results of 4-points bending tests showed that the flexural strength is affected by the prestressing force but not by the shape of join. From the results of 3-points bending tests by which the bending moment and the shear force are simultaneously applied on the joints of the specimens, it is observed that the shape of joint affects on the flexural strength and the crack behavior. The results of two types of bending tests confirmed that the prestressing force according to the design code is appropriate and the joint with two shear keys gives the better performances against the crack of joint.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.333-345
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• 2008

concrete deck bridges are increasingly aplied to twin- girder bridges and open-stel box girder bridges.One of the most dificult isues in the design of shear conect ors is the mater of achieving ful composite action. Many connectors in smal area require a significant section los of precast decks resulting in difficult reinforcement details. In this closer spacing than the required minimum spacing in the design codes was evaluated through static tests. Test results s howed that the ultimate strength decreased as the conector spacing was reduced. The strength enhancement was observed due to aditional reinforcement for precast slabs or for shear pockets. Thus, the design of group stud shear connection needs to anticipate failure modes and the conector failure should be induced. Based on the test results, an empirical equation consi dering stud spacing was proposed to evaluate the ultimate strength of group stud shear conection. Fatigue tests showed n o reduction in fatigue life of the group stud shear conection in the range of this research. Details of the precast decks wer e enhanced using the findings of the study.