• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.605-610
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• 2002

The purpose of this study is to develop an analytic model which can describe the behavior or concrete compressive member strengthened by CFS(Carbon Fiber Sheet) with various cross-sectional shapes such as circular. square, and octagonal and various laminate angles. The failure criterion of laminated CFS is based on Tsai-Wu failure criterion. The stress strain model of confined concrete compressive member is based on an equation proposed by Mander. The effective lateral confining pressure is considered and modified according to various cross-sectional shapes. Octagonal cross-section shows the best results in the aspect of ductility, while circular does in compressive strengthening effects. In addition, [0/0/0/0] laminate in which the direction of fiber is parallel to the direction of principal stress shows the superior strength and ductility than other laminates. The analytic results show that strength and ductility of the analytic model depend on the cross-sectional shapes as well as the laminate angles.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.511-516
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• 2004

The objective of this study is to optimally design FRP-concrete members of a bridge structure. Using the GENESIS7.0 that is a commercial optimization program we performed an optimal design with design parameters that consist of height, width of FRP member, height of concrete. And we practiced an optimal design with the design variables, thickness of upper flange, bottom flange, and web. The results of these studies are summarized as follows : (1) Thickness of composite-concrete is proper at over loon (2) FRP member reaches the optimal section when the width of the FRP member is 20cm its height is 10cm and the height of the composite-concrete is 12cm.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.579-584
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• 1999

In evaluating the ultimate strength of a section for a concrete flexural member, the effect of member length is not usually considered, even though the strength tends to decrease with increase of member length. In this paper the influence of specimen length on flexural compressive strength of concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to axial compression and bending moment were tested using four different length-to-depth ratios(from 1, 2, 3 and 4) of specimens with compressive strength of 58 MPa. Results indicate that the reduction in flexural compressive strength with increase of length-to-width ratios was apparent. A model equation was derived using regression analyses on the experimental data. It was also founded that the effect of specimen length on ultimate strain was negligible, but its effect of the ultimate load and the displacement at center of specimen was distinct. Finally more general model equation is also suggested.

• 한국산업융합학회 논문집
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• 제9권3호
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• pp.183-190
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• 2006

Generally, application of steel pile as deep foundation member needs specials requirement for the connection method between steel pipe and concrete footing. To investigate real compressive behavior of connection member between steel pipe pile and concrete footing, three specimens were tested with carefully designed experimental system. Main test variable is the connection method between steel pipe pile and concrete footing. The bolted bonding method and hook bonding method was considered as the connection method in this study. From the test results gained from experiment, it was conformed that two types of connection method have the almost same compressive resistance capacity. Therefore, we can conclude that these two connection methods can be used as the strengthening method to verify the compressive composite action of concrete and steel pipe pile.

• 콘크리트학회논문집
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• 제11권4호
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• pp.63-71
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• 1999

In evaluating the ultimate strength of a section for a reinforced concrete flexural member, the effect of member length is not usually considered, even though the strength tends to decrease with increase of member length. In this paper the influence of specimen length on flexural compressive strength of concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to axial compression and bending moment were tested using four different length-to-depth ratios (from 1,2,3 and 4) of specimens with compressive strength of 590 kgf/$\textrm{cm}^2$. Results indicate that for the region of h/c <3.0 the reduction in flexural compressive strength with increase of length-to-depth ratios was apparent. A model equation was depth of an equivalent rectangular stress block was larger than that by ACI. It was also founded that the effect of specimen length on ultimate strain was negligible. Finally more general model equation is also suggested.

• 화약ㆍ발파
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• 제32권1호
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• pp.1-9
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• 2014

외부장약 발파시 부재와 폭약의 이격거리에 따른 절단 및 파괴양상을 확인하기 위하여 강 부재와 콘크리트 부재에 TNT 카트리지 폭약을 이용하여 실험을 하였다. 실험 결과 강 부재나 콘크리트 부재에 대한 파괴 장전공식은 다소 보수적인 것으로 판단되었다. 콘크리트 부재에 비해 강 부재가 폭약 이격거리에 대한 파괴영향이 큰 것으로 판단된다. 강 부재의 경우 표준폭약 이상으로 장전해도 폭약이 부재에서 2cm 이격된 경우 절단되지 않고 구부러짐만 나타났다. 같은 이격에 대하여 콘크리트 블록 부재의 경우 구조물의 파괴를 유도하는데 문제가 없을 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.469-472
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• 2005

With all ensuring the fire resistance structure as a method of setting the required cover thickness to fire, the RC is significantly affected from the standpoint of its structural stability that the compressive strength and elastic modulus is reduced by fire. Normally, the degradation of concrete member exposed to fire is largely dependent on the fire scale and fire condition. There is therefore a need to precisely predict the deterioration and fire damage of the exposed member. Thus, this work estimated the temperature distribution inside a member taking into consideration of the thermal properties by means of finite element method(FEM). The estimation results in a little higher prediction value than the experimental value in surface layer and is almost coincident with the experiment as the heating depth increase. From this work it can be known that the simulation application of FEM using the thermal properties of concrete member in high temperature gives rise to the confident prediction in the prediction of temperature distribution.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.427-430
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• 2005

The study for seismic characteristics of square concrete-filled steel tubular (CFT) columns is analytically conducted. For predicting the strength and ductility of CFT columns, fiber analysis technique is used. The analytical results show reasonable agreement with experiment results. The influence of the steel tube on the lateral response of CFT columns is studied for the evaluation of seismic performance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.317-320
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• 2006

In order to determine a minimum thickness of the pultruded GFRP panel as a structural member, some experimental studies were performed. GFRP tubes with 2mm, 4mm, 6mm thickness were manufactured by pultrusion process. First, coupon tests for finding mechanical properties were carried out. Comparisons between test results and analysis results based on classical laminate theory showed large differences in case of 2mm, 4mm specimens. The reason is that it is difficult to apply appropriate pultruding force and keep layered stitched fabric flat for the pultrusion process of complex shaped FRP member with small thickness. On the consequence, we decide 6mm as a minimum thickness of FRP member. Second, 4-point bending tests were performed and the results with compared with numerical analysis. The behavior of FRP tube can be exactly predicted by numerical analysis if buckling analysis is included.

• 한국농공학회지
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• 제40권4호
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• pp.120-129
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• 1998

The tension stiffening in reinforced concrete member means increase of stiffness caused by the effective tensile stress between cracks and the tension softening behavior of concrete. This paper presents on the tensile behavior and tension stiffening of RC tension members. Direct tension tests were performed with a main experimental variables such as concrete strength, rebar diameter and strength. The tension stiffening was analyzed from the load-displacement relationship and was compared with ACI code, CEB model and the proposed by Collins ＆ Mitchell. The results are as follows : The tension behaviors of RC members were quite different from those of bare bar and were characterized by loading and concrete cracking steps. The effect of tension stiffening decreased rapidly as the rebar diameter and strength increased, and the concrete strength increased. The proposed by Collins ＆ Mitchell described well the experimental results, regardless of rebar types and concrete. But, ACI code and CEB model described a little differently, depending on the types. The effect of tension stiffening in RC member was the biggest near at concrete cracking step and decreased gradually to the bare bar's behavior as loading closed to the breaking point. Thus, tension stiffening in RC members should be taken into account when the load-deflection characteristics of a member are required or a precise analysis near the load of concrete clacking is needed.