• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2A
• /
• pp.259-267
• /
• 2008

The ultimate strengths of reinforced concrete deep beams are governed by the capacity of the shear resistance mechanism composed of concrete and shear reinforcing bars, and the structural behaviors of the beams are mainly controlled by the mechanical relationships according to the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model reflecting all characteristics of the ultimate strengths and complicated structural behaviors is presented for the design of simply supported reinforced concrete deep beams. In addition, a load distribution ratio, defined as a magnitude of load transferred by a vertical truss mechanism, is proposed to help structural designers perform the design of simply supported reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of a load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure the ductile shear failure of reinforced concrete deep beams, and the prime design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete influencing the ultimate strength and behavior are reflected upon based on various and numerous numerical analysis results. In the companion paper, the validity of presented model and load distribution ratio was examined by employing them to the evaluation of the ultimate strengths of various simply supported reinforced concrete deep beams tested to failure.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05d
• /
• pp.306-311
• /
• 1996

CANFLEX 연료봉 다발을 구성하는 우라늄 펠릿이 장전된 핵연료봉의 공기중 진동특성을 진동 실험과 유한요소 해석을 통하여 구하였다. 유한요소 해석 시에는 우라늄 펠릿의 강성은 무시하고 질량은 지르칼로이 튜브에 부가하며, 연료봉 양단의 용접부위를 단순 지지보로 처리하는 모델을 제시하였다. 이 모델로부터 얻은 해석결과를 진동실험에서 구한 측정값과 비교하였다.

• Journal of the Korea Concrete Institute
• /
• v.17 no.2 s.86
• /
• pp.213-220
• /
• 2005

Carbon fiber reinforced polymer (CFRP) sheets are becoming increasingly popular for strengthening deteriorated concrete bridges due to their excellent strength and stiffness-to-weight ratio, corrosion resistance, and convenience of construction work. The purpose of this study is to compare the performance of CFRP-strengthened reinforced concrete (RC) beams and to develop a new design formula. Simple beams with 3 m span length were tested to investigate the effect of reinforcing steel ratio and CFRP-reinforcing ratio on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode, the maximum load, and the strain distribution in the section. It is shown that the strain of the strengthened beams is not linearly distributed in the section. A new design formula based on the non-linear distribution of the strain has been derived and showed that it has a good agreement with the various domestic and foreign test results.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06c
• /
• pp.376-379
• /
• 2010

인간의 학습과 기억현상에 있어서 멀티모달 데이터를 사용하는 것은 단순 모달리티 데이터를 사용하는 것에 비해서 향상된 효과를 보인다는 여러 연구 결과가 있어왔다. 이 논문에서는 인간의 순차적인 정보처리와 생성현상을 기계에서의 시뮬레이션을 통해서 기계학습에 있어서도 동일한 현상이 나타나는지에 대해서 알아보고자 하였다. 이를 위해서 가중치를 가진 랜덤 하이퍼그래프 모델을 통해서 순차적인 멀티모달 데이터의 상호작용을 하이퍼에지들의 조합으로 나타내는 것을 제안 하였다. 이러한 제안의 타당성을 알아보기 위해서 비디오 데이터를 이용한 문장생성을 시도하여 보았다. 이전 장면의 사진과 문장을 주고 다음 문장의 생성을 시도하였으며, 단순 암기학습이나 주어진 룰을 통하지 않고 의미 있는 실험 결과를 얻을 수 있었다. 단순 텍스트와 텍스트-이미지 쌍의 단서를 통한 실험을 통해서 멀티 모달리티가 단순 모달리티에 비해서 미치는 영향을 보였으며, 한 단계 이전의 멀티모달 단서와 두 단계 및 한 단계 이전의 멀티모달 단서를 통한 실험을 통해서 순차적 데이터의 단계별 단서의 차이에 따른 영향을 알아볼 수 있었다. 이를 통하여 멀티 모달리티가 시공간적으로 미치는 기계학습에 미치는 영향과 순차적 데이터의 시간적 누적에 따른 효과가 어떻게 나타날 수 있는지에 대한 실마리를 제공할 수 있었다고 생각된다.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.1
• /
• pp.51-58
• /
• 2002

To reduce the story height for high-rise buildings, the TEC Beam is developed as a new composite beam composed of structural tee, precast concrete, stirrup, and site-in-cast reinforced concrete slab. The preliminary test of the proposed system was performed for simple beams and it showed a good behavior. However, for the field application of the system, it is required to develope a steel moment resisting connection using steel brackets on which upper rebars of the TEC BEAM are anchored. In this paper, three types of the proposed system are experimentally investigated. The parameters of the test are as follows: (1) the spacing of transverse bars, (2) the ratio of width of rebar's layer to bracket length. Specimens were classified as semi-rigid full strength by the Eurocode 4. It could be concluded that the proposed moment resisting system shows a good structural behavior and may be applicable in the filed.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.265-268
• /
• 2011

하중 속도에 따른 콘크리트 재료의 역학적 특성은 구조물의 동적파괴거동에 영향을 미친다. 본 연구는, rigid-body-spring network를 이용하여 파괴해석을 수행하고, 거시적 시뮬레이션에서 속도효과를 표현하기 위하여 점소성 파괴모델을 적용하였다. 보정을 위해서 Perzyna 구성관계식의 점소성 계수들이 다양한 하중속도에 따른 직접인장실험을 통해서 결정되었다. 동정상승계수를 이용하여 하중 속도가 증가함에 따른 강도 증가를 표현하였고 이를 실험결과와 비교하였다. 다음으로 느린 하중속도와 빠른 하중속도에 따라 단순 콘크리트 보와 철근 콘크리트 보에 대한 휨 실험을 수행하였으며, 하중 속도에 따라서 서로 다른 균열 패턴을 관찰할 수 있었다. 빠른 하중은 보의 파괴가 국부적으로 나타나게 만드는데, 이는 속도 의존적 재료의 특성 때문이다. 구조적인 측면에서, 보강재는 느린 하중속도에서 균열의 크기를 줄이고 연성을 높이는 데 큰 영향을 미친다. 본 논문은 속도 의존적 거동에 대한 이해와 동적하중에 대한 보강효과를 제시한다.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.5 s.66
• /
• pp.579-589
• /
• 2003

Most beam-to-column connections are symmetrically reinforced because of the reverse action caused by earthquakes. However, in weak-earthquake regions like Korea, asymmetrically reinforced connections could be used. In particular, the connections between concrete-filled tube (CFT) column and H-shape beam could be applied using a simplified lower diaphragm. The tensile capacity or Combined Cross Diaphragm for upper reinforcing was tested using a simple tension test. Four types for lower reinforcing combined Cross, none, horizontal T-bar, and vertical plate were tested using the ANSI/AISC SSPEC 2002 loading program. Horizontal T-bar and stud bolts in vertical flat, bar transmit tensile stress from the beam's bottom flange to filled concrete. All test specimens satisfied 0.01 radian inelastic rotational requirement in ordinary moment frame of AISC seismic provision. According to the results of the parametric studies simplified lower diaphragms demonstrated outstanding strength, stiffness, and plastic deformation capacity which could lead to more sufficient seismic performance in the field.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8654-8664
• /
• 2015

Beam-type structures with non-uniform cross sections are widely used in mechanical, architectural, and civil engineering fields. This paper deals with dynamic characteristics and vibration problems. Governing equations are first derived by using local coordinates. Their solutions are then assumed by using Galerkin's mode summation method. Bisection method is also applied in solving the determinant of the matrix which can provide natural frequencies. Whereas finite element methods adopt admissible functions satisfying only geometric boundary condition, in this study we apply Galerkin's mode summation method which uses eigen-functions satisfying both governing equations and boundary conditions. Modal analysis and experimental tests are finally performed using simply-supported beams with four different non-uniform cross-sections. Our analytical results then show good agreement with experimental ones.

• Journal of the Korea Concrete Institute
• /
• v.18 no.4 s.94
• /
• pp.469-477
• /
• 2006

Models to predict the ultimate strength of simply supported or continuous deep beams with web openings are proposed. The derived equations are based on upper-bound theorem. The concrete is assumed as a perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cutoff. Reinforcing bar is considered as elastic-perfectly plastic material and its stress is calculated from the limiting principal compressive strain of concrete. The governing failure mechanisms based on test results are idealized as rigid moving blocks separated by a hyperbolic yield line. The effective compressive strength of concrete is calculated from the formula proposed by Vecchio and Collins. Comparisons with existing test results are performed, and they show good agreement.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.3
• /
• pp.463-470
• /
• 2002

The TEC-Beam system is a composite beam consisting of structural tee, precast concrete, and cast-in-site reinforced concrete slab. The preliminary test of the proposed system was performed for simple beams, showing good behavior. However, for the field application of the system. TEC-Beam - RC column connection was required to produce a mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection mechanism that transfers the force occurring in the lower part of the TEC-Beam. Thus, this study developed a connection wherein the section of the TEC-Beam was enlarged and the lower part reinforced. Two setups of the proposed system were experimentally investigated. using the anchorage length of reinforcement., i.e., length of the increased section, as test parameter. It could be concluded from the result that the proposed system shows good structural behavior, with potential applicability in the field.