• Structural Engineering and Mechanics
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• 제74권3호
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• pp.435-443
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• 2020

The objective of this study was to determine the effective compressive strength of a column-slab connection with different compressive strengths between the column and slab concrete. A total of eight column specimens were fabricated, among which four specimens were restrained by slabs while the others did not have any slab, and the test results were compared with current design codes. According to ACI 318, the compressive strength of a column can be used as the effective compressive strength of the column-slab connection in design when the strength ratio of column concrete to slab concrete is less than 1.4. Even in this case, however, this study showed that the effective compressive strength decreased. The specimen with its slab-column connection zone reinforced by steel fibers showed an increased effective compressive strength compared to that of the specimen without the reinforcement, and the interior column specimens restrained with slabs reached the compressive strength of the column.

• Computers and Concrete
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• 제21권3호
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• pp.239-248
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• 2018

This study developed and investigated a precast slab track system partially reinforced with glass fiber reinforced polymer (GFRP) rebars in the transverse direction, which mitigated the loss of track circuit current by reducing magnetic coupling between the rails and steel reinforcements. An electric analysis was conducted and the results of the analysis verified that the GFRP rebars mitigate the reduced current strength produced by electro-magnetic induction. In the study, a three-dimensional finite element method and flexural experiments were used to study the mechanical behavior of the proposed slab track.

• Computers and Concrete
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• 제31권6호
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• pp.469-484
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• 2023

The response mechanism of simply supported two-way reinforced concrete (RC) slabs under fire was numerically studied from the view of stress redistribution using the finite element software ABAQUS. Results show that: (1) Simply supported two-way RC slabs undergo intense stress redistribution, and their responses show four stages, namely elastic, elastic-plastic, plastic and tensile membrane stages. There is no cracking in the fire area of the slabs until the tensile membrane stage. (2) The inverted arch effect and tensile membrane effect improve the fire resistance of the two-way slabs. When the deflection is L/20, the slab is in an inverted arch effect state, and the slab still has a good deflection reserve. The deformation rate of the slab in the tensile membrane stage is smaller than that in the elastic-plastic and plastic stages. (3) Fire resistance of square slabs is better than that of rectangular slabs. Besides, increasing the reinforcement ratio or slab thickness improves the fire resistance of the slabs. However, an increase of cover thickness has little effect on the fire resistance of two-way slabs. (4) Compared with one-way slabs, the time for two-way slabs to enter the plastic and tensile cracking stage is postponed, and the deformation rate in the plastic and tensile cracking stage is also slowed down. (5) The simply supported two-way RC slabs can satisfy with the requirements of a class I fire resistance rating of 90 min without additional fire protection.

• 콘크리트학회논문집
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• 제14권3호
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• pp.392-401
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• 2002

The results of analysis of simply supported reinforced concrete slab by special orthotropic plate theory have been reported. This method, however, may be too difficult for some practising engineers. In this paper, the result of analysis of such a plate by means of the beam theory with unit width is reported. By using the "correction factor", the accurate solution for the plate can be obtained by the beam theory. The plate aspect ratio considered is from 1 : 1 to 1 ：6

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.861-866
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• 2000

This experimental were investigated on the influence of steel fiber reinforcement on flexural behavior characteristics of slabs with various steel fiber contents $V_f$ and aspect ratio($\ell $/$\phi$). Deflection, crack widths, and strains of steel bar were measured with every load step. In the results of this experimental, the addition of steel fibers to conventionally reinforced concrete slab increased the ultimate load, reduced the creak width, the average crack spacing, and deflection.

• 한국구조물진단유지관리공학회 논문집
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• 제10권1호
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• pp.97-105
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• 2006

플랫 플레이트 구조에서 고강도 콘크리트를 사용함에 따라서 접합부의 전단강도와 같은 구조성능을 향상시켜서 플랫 플레이트 구조의 단점을 보완하여 장점을 극대화시킬 수 있다고 판단된다. 이에 본 논문에서는 70MPa급 고강도 콘크리트를 사용한 플랫 플레이트구조의 기둥 슬래브 접합부 실험체를 제작한 후에 수직하중과 수평하중의 조합하중을 가력하여 플랫 플레이트구조의 기둥 슬래브 접합부에 대한 전단강도를 비롯한 주요한 구조성능을 평가하고자 한다. 본 연구에서의 실험변수는 슬래브의 철근비와 슬래브에 작용하는 수직하중의 비율로 하였다.

• Coupled systems mechanics
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• 제9권2호
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• pp.163-182
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• 2020

Coupled thermo-mechanical analysis of reinforced concrete slab at elevated temperatures from a fire accounting for nonlinear thermal parameters is carried out. The main focus of the paper is put on a one-way continuous reinforced concrete slab exposed to fire from the single (bottom) side as the most typical working condition under fire loading. Although contemporary techniques alongside the fire protection measures are in constant development, in most cases it is not possible to avoid the material deterioration particularly nearby the exposed surface from a fire. Thereby the structural fire resistance of reinforced concrete slabs is mostly influenced by a relative distance between reinforcement and the exposed surface. A parametric study with variable concrete cover ranging from 15 mm to 35 mm is performed. As the first part of a one-way coupled thermo-mechanical analysis, transient nonlinear heat transfer analysis is performed by applying the net heat flux on the exposed surface. The solution of proposed heat analysis is obtained at certain time steps of interest by α-method using the explicit Euler time-integration scheme. Spatial discretization is done by the finite element method using a 1D 2-noded truss element with the temperature nodal values as unknowns. The obtained results in terms of temperature field inside the element are compared with available numerical and experimental results. A high level of agreement can be observed, implying the proposed model capable of describing the temperature field during a fire. Accompanying thermal analysis, mechanical analysis is performed in two ways. Firstly, using the guidelines given in Eurocode 2 - Part 1-2 resulting in the fire resistance rating for the aforementioned concrete cover values. The second way is a fully numerical coupled analysis carried out in general-purpose finite element software DIANA FEA. Both approaches indicate structural fire behavior similar to those observed in large-scale fire tests.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.327-332
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• 1997

This study is aimed to investigate the effect of load and deflection on steel fiber reinforced concrete slab. Slabs were made with Hooked and Straight types steel fiber and compared a change of steel fiber contents and fiber types. Test were carried out to evaluate he first crack load, maximum load and deflection of slab. At the result, the first crack load, maximum load and energy absorption capacity were increased remarkably as steel fiber contents wee increased. And we found that the deflection of slab at same load ere decreased as steel fiber contents were increased, too. As the aspect ration was increased, the first crack load, maximum load and energy absorption capacity were increased.

• 콘크리트학회논문집
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• 제19권6호
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• pp.727-734
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• 2007

철근과 fiber-reinforced polymer (FRP)의 물리적, 역학적 특성의 차이 및 슬래브 상부 보강재의 기둥 인접부 집중 배근, 그리고 기둥 인접부 슬래브에 강섬유 콘크리트 (SFRC)의 타설 등에 따른 2방향 슬래브의 펀칭 전단 거동에 대한 효과를 평가하였다. 펀칭 전단강도, 강성, 연성, 변형률 분포 그리고 균열 제어 성능 등을 파악하였다. 실험 결과 기둥 인접부의 슬래브에 집중 배근을 하거나 SFRC를 타설하는 것은 glass fiber-reinforced polymer (GFRP) 바로 보강된 슬래브의 펀칭 전단 거동을 향상시켰다. 기둥 인접 구역에 집중 배근된 슬래브의 실험 결과를 다양한 설계기준과 타 연구자에 의해 제안된 예측식과 비교하였으며, 집중 배근으로 인한 이점을 예측식에 반영할 수 있도록 집중 배근된 슬래브의 철근비를 산정하는 합리적인 방법도 제안하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.372-378
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• 2005

Finite element analysis of concrete slab system in apartment building was executed using the tables of orthogonal arrays, and optimal design process was proposed. At first, experimental results show that sound peak components to influence the overall level and the rating of floor impact sound insulation were coincident with natural frequencies of the reinforced concrete slab. Finite element model of concrete slab was compared with experimental results, and well corresponded with an error of less than 10%. The tables of orthogonal arrays were used for finite element analysis with 8 factors. 3 related to material properties and 5 related to slab shape parameters and its results were analyzed by statistical method, ANOVA. The most effective factor among them was slab thickness, and main effect factor from slab shape parameters was different from each natural frequency. The interaction was found in the higher mode over $3^{rd}$ natural frequency. From main effect plot and interaction plot, the optimal design factor to increase the natural frequency was determined.