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PSC철도교량 격벽부의 3차원 거동 및 스트럿-타이 모델 해석
송하원(Song Ha-Won),변근주(Byun Keun-Joo),김형운(Kim Hyoung-Woon),김영훈(Kim Young-Hoon) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
The function of diaphragms at abutments and piers of prestressed concrete (PSC) box girder train bridge is to transfer forces from the superstructure onto bearings or column and to stiffen the superstructure cross-section against in-plane deformation. Due to large stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than designs for other structual members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from behavior of the deck slab obtained from two dimensional analysis of the bridge, which is basis for the design of deck slab. In this paper, three dimensional behavior of deck slab near diaphragm of PSC box girder train bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling. Then, strut-and-tie model is applied to design the diaphragm of PSC box girder train bridge. The modeling techniques in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.
PSC 박스거더 철도교량의 해석 및 스트럿-타이 모델에 의한 격벽부 설계
송하원(Song Ha-Won),김형운(Kim Hyoung-Woon),김영훈(Kim Young-Hoon),변근주(Byun Keun-Joo) 한국철도학회 1998 철도저널 Vol.1 No.1
The functions of diaphragms at abutments and piers of PSC box girder railway bridge are to transfer forces from the superstructure onto bearings or columns and to stiffen the superstructure cross-section against in-plane deformation. Due to stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than those for other structual members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from that of the deck slab obtained from two dimensional analysis of the bridge, which is basis for the design of deck slab. In this paper, three dimensional behavior of deck slab near the diaphragm of prestressed concrete (PSC) box girder railway bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling and using the strut-and-tie model design of the diaphragm are presented. The modeling techniques used in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.
송하원,서철,Song, Ha-Won,Seo, Chul 한국콘크리트학회 1996 콘크리트학회지 Vol.8 No.2
콘크리트의 국소화현상은 콘크리트의 연화거동에 수반되어 변형이 국부적으로 집중되는 현상으로 콘크리트 구조물의 극한하중을 지배한다. 본 연구에서는 연화거동에 따른 변형률국소화현상을 일으키는 콘크리트를 국소영역과 비국소영역으로 나누어 모형화하였으며 불균질재료의 평균화개념을 이용하여 콘크리트의 국소화거동을 정식화하였다. 본 연구에서는 정식화된 모형을 사용하여 일축압축 및 일축인장하중을 받는 콘크리트의변형의 국소화 현상을 재현하였으며, 제안된 모형이 일축하중하의 콘크리트의 국소화거동을 잘 재현할 수 있음을 실제 실험결과와의 비교를 통하여 검증하였다. 해석결과로부터 일축압축하중하의 콘크리트의 국소영역의 크기는 콘크리트의 최대골재치수의 3배가 적당하고, 시편의 길이에 따른 콘크리트의 크기효과도 재현할 수 있음을 보였다. 또한 제안된 모형식에 직접인장시험에서 구해진 인장연화곡선의 사용이 일축인장하의 콘크리트의 국소화현상을 잘 표현하는데 적합함을 알 수 있었다. Localization of concrete is a phenomenon such that the deformation of concrete is localized in finite region with softening behavior and it governs ultimate load of concrete. In this Paper, concrete under strain localization was modeled with localization region and non-localization region and lc~calization behavior was formulated based on averaging concept of heterogeneous material. By using the formulation, the localization phenomena of concrete under uniaxial loadings were well predicted. The analytical results show that size of localization region of concrete under uniaxial compression is three times of maximum aggregate size and the size effect of concrete is well predicted. The use of tension-softening curve obtained from direct tension test is suitable for well prediction of localization of concrete under uniaxial tension.
시간의존성을 고려한 해안가 철도 콘크리트 구조물에 대한 내구성 설계 기법의 개발
송하원(Ha-Won Song),백승우(Seung-Woo Pack),이선호(Son-Ho Lee),권진수(Jin-Su Kwen),이현정(Hyun-Jung Lee) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper presents a refined design model for current railroad design code on concrete structures exposed to marine environment. A time-varying diffusion coefficient(D) as well as surface chloride(C<SUB>s</SUB>) and chloride threshold level(C<SUB>lim</SUB>) are studied. Averaging value of the D with time over exposed duration were used to refined durability design model to consider time dependent characteristic of D. The values for C<SUB>s</SUB> and C<SUB>lim</SUB> for the seashore in Korea revised for realistic durability design. The proposed model was verified by the so-called performance-based durability design, which is widely used in recent durability design code. Results show that the current standard specification underestimates durability performances of concrete structures exposed to marine environment, so that the cover depth design using current durability evaluation in the standard specifications is very much conservative. Thus, it is found that proposed durability design models for the railroad design code for railway concrete structures can be used effectively for service life design of concrete structures in marine environment.