순수(純粹)비틀림을 받는 철근(鐵筋)콘크리트 부재(部材)의 내력(耐力)

신현묵,김은겸,김선일,Shin, Hyun Mook,Kim, Eun Kyun,Kim, Seon Il 대한토목학회 1988 대한토목학회논문집 Vol.8 No.2

RC 부재(部材)에 대한 정밀도 높은 하중이력곡선(荷重履歷曲線)의 제안은 합리적인 설계법(設計法)의 수립이라는 관점으로 볼 때 매우 중요하다. 순수비틀림을 받는 RC 부재(部材)의 비틀림모멘트와 비틀림각(角) 관계곡선을 최근 제안한 사람은 Collins, Hsu 등이다. 그러나 그의 비틀림 내력평가(耐力評價) 결과는 극한상태를 제외하고는 모든 하중영역(荷重領域)에 있어서 상당히 과소평가되고 있다. 본 연구에서는 구성방정식(構成方程式)에 콘크리트의 인장강성(引張剛性) 및 수정된 콘크리트 softening 계수(係數)를 도입하여 임의의 하중단계에서도 비틀림내력(耐力)의 정밀도를 높이는데 그 목적(目的)을 두었다. 특히 이론해석(理論解析)의 타당성을 검토하고자 14체(體)의 RC 부재(部材)를 제작하여 재하실험(載荷實驗)을 실시하였다. To establish the rational design method, it is very important that predict accurately load-deformation response on reinforced concrete members. Torque-twist curves of reinforced concrete members in pure torsion were proposed recently by Collins and Hsu, etc. But, it is found that torsional strength of reinforced concrete members based on Hsu's theory is underestimated in the over-all load region except the ultimate state. In this paper, an attempt is made to present the higher-precision of torsional strength on arbitrary loading condition. For this purpose, constitutive equations are derived from which an estimate can be made of the torsional behavior of reinforced concrete members under the pure torsion. Tension stiffness of concrete in both the cracked and uncracked state have been considered. A softening effect that reduces the strength of the concrete by the diagonal cracking of concrete have been appropriately deliberated. Particularly, the experiments was done with 14 test beams to investigate the validity of theoretical analysis.

외부 후긴장 공법 적용에 따른 무도상 판형교의 동적거동 분석

민낙기(Rak-KI Min),김은겸(Eun-Kyun Kim),이희업(Hee-Up Lee),박용걸(Yong-Gul Park) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-

The major objective of this study is to investigate the effects and application of external post-tensioning method for steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis, field test and laboratory test for the lateral dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the lateral dynamic response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease lateral acceleration and deflection on steel plate girder bridge for serviceability. And the external post-tensioning method reduce dynamic maximum displacement(about 10~24%), the increase of dynamic safety is predicted by adopting external post-tensioning method. From the dynamic test results of the servicing steel plate girder bridge, it is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method The servicing steel plate girder bridge with external post-tensioning has need of the reasonable reinforcement measures which could be reducing the effect of lateral dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

염해 환경에 있는 지하철 콘크리트 구조물의 내구성 향상 대책수립에 관한 연구

이무관(Lee Moo-Kwan),김은겸(Kim Eun Kyun),김대호(Kim Dae Ho) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-

Durability of concrete has been currently issued in the engineering societies and a large number of studies on the concrete corrosion in salty environment have been performed. The reinforcement corrosion, which is the primary reason of deterioration of the concrete structure exposed to chloride environment, is caused by the chloride ions infiltration owing to underground water seeping into the concrete. In this study. the endurance periods using the diffusion equation of the concrete specification have been evaluated on the concrete structures with different addictives for the brand new R/C subway structure exposed to seashore underground water. Furthermore, the guidance for proper use of the addictives and the reasonable thickness of concrete cover are derived for concrete mixing. From the result of the evaluation corresponding to salt damage for Inchon subway line 1, the endurance periods of the ordinary Portlaudcement concretes are represented as 42~75 years and fail to achieve the objective period of 100 years. However, the lower water-cement ratio expands the endurance period and the blast furnace slag concrete with small quantity of the silica fume, which shows the best performance of corrosion resistance in this study, represents more than 170 years of the endurance period. Moreover, the case of use of blast furnace slag and fly ash together shows the endurance period of 134~171years and it means that the result very satisfies the objective endurance period.

수화열 발생인자가 지하철 콘크리트 구조물의 내구설계에 미치는 영향

임영수(Lim Young-Su),김은겸(Kim Eun Kyun),성기한(Sung Ki Han) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-

With the recent continuous expansion of subways, newly created subways tend to have lower locations and wider sections. Furthermore, since box structures and evacuating tunnels are classified into a category of mass-concrete, the thermal-stress, emitted from the inside, causes cracks to structures from the inception of constructing. In this paper, thermal-stress analysis and durability evaluation of box structure were carried out to investigate relationship between durability and parameter causing the heat of hydration. Through the examination, this paper tries to find out satisfactory solutions to regulated thermal crack and ensure the required duration period. The results of this paper showed that to control thermal crack and guarantee the required duration period it was more effective to use low-heat-portland cement and moderateheat-portland cement. As cement volume due to reduction of water-cement ratio increased, the possibility of thermal cracks occurrence increased but results of durability evaluation was different depending on evaluation method. The results showed that the appropriate water-cement ratio to control the heat of hydration and satisfy the required durability was 45~55%. And it was showed that during placement of concrete blocks ambient temperature affect the heat of hydration, thermal crack and long-term durability largely and when concrete was placed at low temperature to control thermal crack, it need to try to guarantee the required duration period. Henceforth, by studying not only internal and external conditions, such as the relative humidity and the unit weight, but also methods, to evaluate durability, in accordance with domestic situations, more reasonable design of durability should be achieved.

외부후긴장 보강공법이 판형교의 거동에 미치는 영향

민낙기(Min Rak-Ki),성덕룡(Sung Deok-Yong),김은겸(Kim Eun-Kyun),이희업(Lee Hee-Up),박용걸(Park Yong-Gul) 한국철도학회 2006 한국철도학회 학술발표대회논문집 Vol.- No.-

In strengthening structure, the external post-tensioning method which secure clearness in the structure analysis process is adopted to bridge as well as architecture structure. Therefore, the major objective of this study is to investigate the effects and application of external post-tensioning method for steel plate girder bridge. It analyzed the mechanical behaviors of steel plate girder bridge with applying external post-tensioning on the finite element analysis and laboratory test for the dynamic characteristics. As a result, the reinforcement of steel plate girder bridge the external post-tensioning method are obviously effective for the response which is non-reinforced. The analytical and experimental study are carried out to investigate the post-tension force decrease stress and deflection on steel plate girder bridge for serviceability. It is investigated that the change degree of natural frequency is very low with applying the external post-tensioning method. The servicing steel plate girder bridge with external post-tensioning is the reasonable reinforcement measures which could be secured the stability of dynamic behavior and increase a dropped durability.