• 한국안전학회지
• /
• 제32권6호
• /
• pp.68-74
• /
• 2017

To predict the damage of Reinforced Concrete (RC) structures from mass explosion, Pressure-Impulse (P-I) curves representing the relationship between peak pressure and impulse based on damage criteria are essential. There are P-I curves developed by the U.S. DoD without detailed explanation regarding validation. In this study, full scale explosion tests were conducted measuring response of RC slab to modify and validate pre-existing P-I curves. Four same RC slabs were prepared, and placed at different distances, which are fixed to steel frame with concrete base. Scaled distances were selected to show different failure types using P-I curve based on Single Degree Of Freedom (SDOF) model. It was found that SDOF model can be used to evaluate and identify one-way RC slab damage with difference damage criteria.

• 대한토목학회논문집
• /
• 제33권4호
• /
• pp.1303-1313
• /
• 2013

본 연구에서는 콘크리트 슬래브 궤도를 가지는 교량의 사용성 검토에 있어 단위 축하중, 단위 수직 단차, 단위 회전에 의해 발생되는 레일 지지점의 작용력에 대한 기준 값을 구하였다. 해석방법에 있어서는 레일이 탄성 스프링에 의해 연속적으로 지지되는 모델과 이산적으로 지지되는 모델이 이용되었다. 해석결과 얻어진 레일 지지점에서의 작용력은 콘크리트 궤도의 사용성 검토에서 참조되고 있는 DS 804 기준에 제시된 값과 비교되였으며, 그 결과는 잘 일치하였다. 또한, 레일 지지점의 간격과 체결장치의 강성이 레일 지지점에서의 작용력에 미치는 영향을 분석하였다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.369-372
• /
• 2006

Flat plate slab systems have been commonly used as a gravity force resisting systems, which should be constructed with lateral force resisting systems such as shear walls and moment resisting frame. ACI 318(2005) allows the Direct design method, the equivalent frame method (ACI-EFM) under gravity loads and the finite-element models, effective beam width models and equivalent frame models under lateral loads. ACI-EFM can be used for gravity loads as well as lateral loads analysis. But the method may not predict the behavior of flat plate slabs under lateral loads. Thus Previous study developed a Modified equivalent frame method(Modified-EFM) which could give more precise answer for flat plate slab under lateral loads. This study is to verified the accuracy of a Modified-EFM under combined lateral and gravity loads. The accuracy of this model is verified by comparing the results using the Modified-EFM with the results of finite element analysis. For this purpose, 7 story building is considered. The analysis results of other existing models are included. The analysis results show that Modified-EFM produces comparable drift and slab internal moments with those obtained from finite element analysis.

• 한국도로학회논문집
• /
• 제15권1호
• /
• pp.95-102
• /
• 2013

PURPOSES: The existing method evaluating the existence of the hollows in concrete pavement does not consider the stiffness of pavement. In addition, the method uses unreasonable logic judging the hollow existence by the deflection caused by zero loading. In this study, the deflection of slab corner due to heavy weight deflectometer (HWD) was measured in concrete pavement sections where underground structures are located causing the hollows around them. METHODS: The modulus of subgrade reaction obtained by comparing the actual deflection of slab to the result of finite element analysis was calibrated into the composite modulus of subgrade reaction. The radius of relative stiffness was calculated, and the relationship between the ratio of HWD load to the radius of relative stiffness and the slab deflection was expressed as the curve of secondary degree. RESULTS: The trends of the model coefficients showing width and maximum value of the curve of secondary degree were analyzed by categorizing the pavement sections into three groups : hollows exist, additional investigation is necessary, and hollows do not exist. CONCLUSIONS: The results analyzed by the method developed in this study was compared to the results analyzed by existing method. The model developed in this study will be verified by analyzing the data obtained in other sections with different pavement structure and materials.

• Steel and Composite Structures
• /
• 제45권6호
• /
• pp.895-905
• /
• 2022

Composite flooring systems consisting of cold-formed steel joists and reinforced concrete slabs offer an efficient, lightweight solution. However, utilisation of composite action to achieve enhanced strength and economical design has been limited. In this study, finite element modelling was utilised to create a three-dimensional model which was then validated against experimental results for a composite flooring system consisting of cold-formed steel joists, reinforced concrete slab and steel bolt shear connectors. This validated numerical model was then utilised to perform parametric studies on the performance of the structural system. The results from the parametric study demonstrate that increased thickness of the concrete slab and increased thickness of the cold formed steel beam resulted in higher moment capacity and stiffness of the composite flooring system. In addition, reducing the spacing of bolts and spacing of the cold formed steel beams both resulted in enhanced load capacity of the composite system. Increasing the concrete grade was also found to increase the moment capacity of the composite flooring system. Overall, the results show that an efficient, lightweight composite flooring system can be achieved and optimised by selecting suitable concrete slab thickness, cold formed beam thickness, bolt spacing, cold formed beam spacing and concrete grade.

• Structural Engineering and Mechanics
• /
• 제92권2호
• /
• pp.149-161
• /
• 2024

Previous research has identified inadequate flexibility in concrete pavements due to the use of high-strength concrete mixtures. This research investigates whether this problem can be addressed by partially replacing some fine and coarse aggregate components with waste rubber from shredded tires, the safe disposal of which otherwise is a major environmental concern. Using finite element software ABAQUS, this study analyses 3D pavement model behavior in terms of internal stress development and deflection at critical load points. This analysis is carried out for concrete slabs of differing waste rubber proportions and varying thicknesses. Results show that the maximum tensile stress is reduced, and maximum deflection is increased as the rubber content in pavement concrete slab is increased. The stresses and deflection of concrete pavement slab are reduced as the thickness of the slab is increased. The influence of increasing the base coarse modulus is significant in terms of reduction in tensile stress development. However, the reduction in deflection is found to be relatively marginal, especially in low-percentage rubberized pavement concrete slabs.

• 콘크리트학회논문집
• /
• 제21권5호
• /
• pp.599-609
• /
• 2009

2층 규모의 철근콘트리트조 및 포스트텐션조 무량판구조를 1/3 스케일로 축소하여 제작한 실험체의 진동대 실험 결과를 바탕으로 무량판구조의 모델링 기법을 향상하고자 하는 연구를 수행하였다. 이 연구에서 적용한 모델링 방법은 슬래브의 휨모멘트에 의한 휨파괴, 불균형모멘트의 전달에 의한 휨파괴 및 펀칭전단파괴에 의한 슬래브-기둥 접합부의 모멘트 전달능력 상실등의 영향을 반영하는 매우 포괄적인 구조해석 방식이다. 펀칭전단파괴에 대해서는 중력비와 층간변위각에 기초한 한계상태 모델이 적용되었다. 이 논문에서 제안된 비선형 모델은 무량판구조의 진동대 실험 결과와 잘 부합하는 것으로 나타났다.

• 콘크리트학회논문집
• /
• 제14권4호
• /
• pp.615-622
• /
• 2002

철근콘크리트 무량판 구조의 내력 및 변위를 합리적으로 예측하기 위해서는 슬래브의 휨 강성을 고려한 해석모델이 필요하다. FEMA 273과 ACI 318-99에서는 횡 하중에 대한 슬래브의 해석모델들을 제시하고 있으나 실제적인 적용 방법론은 언급하고 있지 않다. 본 연구에서는 무량판 슬래브의 모델링 방법론을 정립하고 이를 내진설계에 어떻게 적용할 것인가에 대하여 연구하였다. 연구결과는 다음과 같다. 1) 무량판 구조의 3차원 해석시 슬래브의 휨 강성을 적절히 고려하기 위해서는 본 연구진이 제시하는 유효보폭 모델을 적용하는 것이 바람직하다. 2) 예제 무량판 건물 해석에서 슬래브의 균열효과를 고려한 유효보폭을 이용할 경우 해석결과는 횡변위에 대하여 상한값을 나타낸 반면 유효보폭 계수만을 고려한 모델은 접합부 불균형 모멘트에 대하여 상한값의 결과를 나타냈다.

• Steel and Composite Structures
• /
• 제21권5호
• /
• pp.1105-1119
• /
• 2016

In this study, it is presented that a new developed approach for equivalent area-distributed loading (EADL) induced from a single concentrated force. For the purpose, a full scale 3D steel formwork system was constructed in laboratory conditions. A developed load transmission platform was put on the formwork system and loaded step by step on the mass center. After each load increment, displacement was measured in several crictical points of the system. The developed platform which was put in to slab of formwork to equivalently distribute the load from a point to the whole slab was constituted using I profiles. A 3D finite element model of the formwork system was analyzed to compare numerical displacement results with experimental ones. In experimental tests,difference among the displacements obtained from reference numerical model (model applied EADL) and main numerical model (model applied single load using a load cell via load transmission platform) is about %13 in avarage. Difference among the displacements obtained from experimental results and main numerical model under 30 kN single load is about %11 in avarage. The results revealed that the displacements obtained experimentally and numerically are dramatically closed to each other. It is highlighted from the study that the developed approach is reliable and useful to get EDL.

• 한국소음진동공학회논문집
• /
• 제21권9호
• /
• pp.805-812
• /
• 2011

This study investigated the characteristics of heavy-weight floor impact sounds of box-frame type structure using 1:10 scale model. Ten types of floor structures(bare slabs and floating floors) were evaluated in terms of dynamic stiffness and loss factor. Floor vibrations and radiated sounds generated by simulated impact source were also measured. The results showed that the bakelite was appropriate for simulating concrete slab in the 1:10 scale model, and surface velocity and sound pressure level of concrete slab measured from the scale model showed similar tendencies with the results from in-situ in frequency domain. It was also found that dynamic behaviors of layered floor structures in the 1:10 scale model were similar to those in a real scale. Therefore, the use of 1:10 scale model would be useful for evaluating the heavy-weight floor impact sound insulation of layered floor structures when the frequency-dependent dynamic properties of each material are known.