• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.641-652
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• 2007

In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, is was confirmed that the calculated axial forces of tower leg members were distributed to $80{\sim}90%$ of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.

• Fire Science and Engineering
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• v.27 no.6
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• pp.38-43
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• 2013

As a preliminary study to evaluate the reliability of the calculation method of fire load for residential furniture combustibles, the present study estimates the fire load considering the volume data obtained by the 3D geometrical information of combustibles and material properties based on the literature survey and sample burning test. A kitchen sink cabinet, couch and workstation were investigated for estimating its fire load and real fire test have been performed to measure total energy released from the combustibles. Based on total energy measured from real fire test, the relative error of the estimated fire load due to literature survey and measured material properties showed 6~120% and less than 20%, respectively. It shows that the estimation error of fire load are greatly affected by its material properties as well as geometrical information of combustibles and the present study will be able to contribute to accurate estimation of fire load.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.135-144
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• 2011

Recently, researches about fiber reinforced polymer (FRP) which has excellent durability, corrosion resistance, and tensile strength as a substitution material to steel tendon have been actively pursued. This study is performed to examine FRP tendon used prestressed beam's safety under service load. The specimen was a prestressed concrete beam with internal bonded FRP tendon. In order to compare the member fatigue capacity, a control specimen of a prestressed concrete beam with ordinary steel tendon was tested. A fatigue load was applied at a load range of 60%, 70%, and 80% of the 40% ultimate load, which was obtained though a static test. The fatigue load was applied as a 1~3 Hz sine wave with 4 point loading setup. Fatigue load with maximum 1 million cycles was applied. The specimen applied with a load ranging between 40~60% did not show a fatigue failure until 1 million cycles. However, it was found that horizontal cracks in the direction of tendons were found and bond force between the tendon and concrete was degraded as the load cycles increased. This fatigue study showed that the prestressed concrete beam using FRP tendon was safe under a fatigue load within a service load range. Fatigue strength of the specimen with FRP and steel tendon after 1 million cycles was 69.2% and 59.8% of the prestressed concrete beam's static strength, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.103-103
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• 2004

실제 작용하는 하중상태는 요소의 형상과 작용하중의 복잡성 때문에 혼합모드 하중상태를 나타낸다. 또한 혼합모드 피로균열은 전파과정 동안 부재의 구속형상이나 외부 작용하중의 급격한 변화에 의해서도 영향 받게 된다. 이로 인하여 피로균열은 균열선단에서 지속적이면서 급격한 응력 재분배의 상태를 경험한다. 그러므로 다양한 응력 재분배 상태에서의 혼합모드 피로균열에 대한 고찰이 필요하다. 본 연구에서는 응력 재분배상태 하에서 나타나는 혼합모드 피로균열의 전파거동에 대한 특징이 실험적으로 고찰되었다.(중략)

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.273-287
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• 2006

This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.639-648
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• 2003

The objective of this study is to evaluate in-plane and out-of-plane moment transmission capacity of H-shaped beams about design load by stud connector. Four specimens were tested under monotonic moment loading condition in each case to evaluate those. The parameter of tests is the size of the H-shaped beams. The results show that moment transmission capacity of H-shape beams in the serviceability limit state by stud connectors is excellent observing to the design code of steel structures of Architectural Institute of Korea.

• Composites Research
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• v.25 no.5
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• pp.147-153
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• 2012

In this paper, static perforation tests are conducted to predict the penetration energy for the composite laminates subjected to high velocity impact. Three methods are used to analyze the perforation energy accurately. The first method is to select the perforation point using the AE sensor signal energy, the second method is to retest the tested specimen and use the difference between initial and retested perforation energy, and the third method is to select the perforation point based on the maximum loading point in the retested load-displacement curve of the tested specimen. The predicted perforation energy results are presented and verified by comparing with those by the high velocity tests.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.285-291
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• 2011

In this study the mechanical performance of the new wave dissipating block is evaluated through experiment and numerical analysis. Also, by selecting adequate reinforcement, the improvement of the structural performance is examined. The reinforcement is designed by predicting the amount of tensile force and the location where the tensile stress develops in the new wave dissipating block through numerical analysis. The new wave dissipating block is reinforced with the ordinary steel bars and the fiber reinforced plastic(FRP) bars which have advantages in ocean environment in terms of corrosion and fatigue. The test result shows that the fracture resistance of the un-reinforced concrete block is 350 kN which is about 6.2 times that of the weight of the block. All the test blocks which are reinforced by either steel of FRP bars show strength capacity of over 900 kN which is the maximum load of the test equipment. Although the single reinforcement with larger-diameter bars has advantage in terms of construction convenience, it is recommended to use multiple number of smaller-diameter bars in order to reduce the crack width.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.209-219
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• 1999

This paper describes an experimental study planned to examine the effects of important design variables which were used in the proposed equation by authors. Fourteen beams and slabs were designed with the variables, such as effective prestress, concrete strength, amount of tendons, amount of bonded reinforcements, loading type, and span/depth ratio. Then, deflections and tendon stresses were measured and compared according to the parametric variations of the selected variables. It was found that the tendon stress increment decreases as the level of effective prestress or the amount of unbonded tendons and bonded reinforcements increases. Also, the contributions of concrete strength, and loading type were observed to affect on the tendon stresses. However, the stress increments of unbonded tendon were minimal alt high values of span/depth in contrast with the ACI code.

• Geotechnical Engineering
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• v.13 no.4
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• pp.163-176
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• 1997

It has long been recognized that the H-beam steel rib has many shortcomings when used as a steel support in tunneling. One of the major shortcomings is the shotcrete shadow created behind H-beam flange which eventually reduces the load bearing capacity of shotcrete shell. In many European countries, plate girder as the H-beam steel rib has been replaced by lattice girder which has many advantages over the H-beam steel rib. Successful application of the lattice girder as a steel support requires a thorough investigation on the load bearing capacity of the lattice girder. Therefore, laboratory bending and compression tests were conducted on lattice girders with the aim of investigating the load bearing capacity of the lattice girders. The results of tests show that the load bearing capacity of laIn twice girders is higher than that of H-beams, which indicates that the lattice girder can be effectively used as a support in tunneling.