• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.71-75
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• 2003

최근 특별한 연약지반 처리공법을 적용하지 않고 자중을 감소시키고 구조적인 특성을 이용하여 연약지반 위에 설치하는 방파제가 제안ㆍ개발되고 있다. 일본에서는 자중을 가볍게 하고 파랑 하중을 역T형 구조와 말뚝을 이용하여 지지하는 구조를 시공한 사례도 있으며(문사강지 등, 1989), 국내에서는 Fig. 1과 같이 역T형 콘크리트 방파제의 자중만으로도 과도한 압밀침하가 발생되는 아주 연약한 지반에서 방파제의 자중을 줄이기 위해 부력통을 설치하고 설계 하중은 지중에 벽체를 설치하여 지지하는 구조를 제안하고 그 성능을 평가한 바 있다(권오순 등,2001 ; 권오순 등, 2002). (중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.64-71
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• 2016

In this paper, when the composite beam is made with UHPC deck and steel girder, the steel girder takes the form of the inverted-T shape without top flange because of high strength and stiffness of UHPC deck. There is no evaluation by experiment and analysis about the shear connector behavior on the web of steel girder and flexural behavior of inverted-T shape composite beam. By this reason, this study compares between experiment and analysis by using tension softening model of UHPC on the basis of flexural test results of 16 members considering compressive strength of UHPC, spacing of stud and thickness of deck as variables. The results of tensile strength of UHPC by inverse analysis were 6.57 MPa(in case of 120 MPa) and 9.57 MPa(in case of 150 MPa). In case of the test members with small stud spacing, the results of analysis and test were close clearly, and the test members with thick deck and low UHPC compressive strength also similar, but effects were small. As it compared between analysis and experiment totally, the results of analysis and experiment agree well. So the tension softening model of UHPC is reasonably reflected on the real behavior of composite beam of UHPC.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.03a
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• pp.47-64
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• 1996

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.733-740
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• 2004

This study presents the behaviors of the typical architectural precast prestressed concrete beams, inverted tee and rectangular beams, subjected to combined flexural and torsional loads. For this purpose, two inverted-tee beams were designed with a parking live load, $5 kN/m^2$, and a market load $12 kN/m^2$ according to the currently used typical shape in the domestic building site. Also, two rectangular beams were also designed as the same bottom dimension and area, and reinforced for similar strength as in the cases of inverted tee beams. Total of four beams were tested, under combined bending and torsion, analysed and compared. Test results showed that the cracking and ultimate flexural strength of the beams decreased under torsional loading. However, two different shaped-beams had roughly the same load resisting capacity in service and ultimate states.

• Geotechnical Engineering
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• v.14 no.2
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• pp.31-40
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• 1998

To verify the reinforcing effect of the strips which are inserted in the backfill, but not connected to the face wall, model tests are executed. As the reinforcing effect is expected to reduce the active thrust acting on the retaining wall, test programmes included the measurements of the thrust. As a result. it is ascertained that the active thrusts are reduced by as much as 50%. Besides, efficient arrangement and the optimum length of the strips are verified. And the the number of reinforcing strips are increased, are close to the Rankine's hypothesis.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.185-193
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• 2015

Ultra high performance concrete (UHPC) has been developed to overcome the low tensile strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.761-769
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• 2014

Ultra high performance concrete (UHPC) has been developed to overcome the low strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.677-685
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• 2015

In a will to subdue the brittleness as well as the low tensile and flexural strengths of ordinary concrete, researches are being actively watched worldwide on steel fiber-reinforced Ultra High Performance Concrete (UHPC) obtained by admixing steel fibers in ultra high strength concrete. For the purpose of maximizing advantage of UHPC, this study removes the upper flange of the steel girder to apply an inverted T-shape girder for the formation of the composite beam. This paper intends to evaluate the behavior of the shear connectors and the flexural characteristics of the composite beam made of the inverted T-shape girder and UHPC slab using 16 specimens considering the compressive strength of concrete, the mixing ratio of steel fiber, the spacing of shear connectors and the thickness of the slab as variables. In view of the test results, it seemed that the appropriate stud spacing should range between 100 mm and 2 or 4 times the thickness of the slab. Moreover, the relative displacement observed in the specimens showed that ductile behavior was secured to a certain extent with reference to the criteria for ductile behavior suggested in Eurocode-4. The specimens with large stud spacing exhibited larger values than given by the design formula and revealed that the shear connectors developed larger ultimate strength than predicted owing to the action of UHPC and steel after non-composite behavior. Besides, the specimens with narrow stud spacing failed suddenly through compression at the upper chord of UHPC before reaching the full capacity of the shear connectors.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.353-364
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• 2011

In a previous research performed by the authors, the allowable compressive stress coefficient (K) in pretensioned members with rectangular section at transfer was proposed based on strength design theory. In this study, a subsequent research of an enormous analysis was performed to determine the K factor for Tee and inverted Tee section members, considering the effect of section height (h), section type, amount of tendons ($A_{ps}$), and eccentricity ratio (e/h). Based on the analysis results, the allowable compressive stress coefficients (K) for Tee and inverted Tee section members at transfer were derived, which limit the maximum allowable stresses as 80% and 70% of the compressive strengths at the time of release for Tee section and inverted Tee section, respectively. And these were larger than the allowable stresses specified in domestic and other international codes. In order to verify the proposed equations, they were compared to the test results available in literature and other codes, which showed that the allowable stresses in domestic and international codes are unconservative for the cases with low eccentricity ratios while conservative for those with high eccentricity ratios. The proposed equations, however, estimate the allowable stresses of the Tee and inverted Tee section members reasonably close to test results.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.659-670
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• 2012

The purpose of this study is to formulate the local displacement and moments of a plate stiffened with open ribs according to the dimensions of stiffened plates. Analyzed results of various plates stiffened with rectangular and reverse T ribs show that the effect of the lower flange to the local behavior is very small, so the local behavior can be expressed by ratio functions of the rib space, web thickness, web height and plate thickness and the ratio functions of rectangular and reverse T ribs can be unioned. The application of ratio functions to other types of stiffened plates shows that the increment of the error ratio is so small compared with examples of this study that the applicability of this study is proved.