scholarly journals FIRE RESISTANCE PROVIDING OF HOLLOW‐CORE CONCRETE SLABS USING SHEET BUILDING MATERIALS

Fire Safety ◽  
2019 ◽  
pp. 72-77
Author(s):  
A. A. Renkas
Keyword(s):  
Heat Transfer ◽  
Fire Resistance ◽  
Material Properties ◽  
Concrete Slab ◽  
Radiation Heat Transfer ◽  
Temperature Fields ◽  
Concrete Slabs ◽  
Hollow Core ◽  
Radiation Heat ◽  
Core Concrete

Introduction. This paper deals with the analysis of world experience in fire resistance providing of hollow‐core concrete slabs. To protect concrete structures are used many structural applications: thermal coatings and materials. The research first analyzes main methods and hypothesis using to make temperature analysis of solution fire resistance of concrete structures. Problem of making temperature analysis of hollow‐core concrete slabs are nonlinear thermal material properties and radiation heat transfer in the hollow-cores. The aim of this paper is to establish the temperature distribution in hollow‐core concrete slab considering radiation heat transfer in the hollow-cores in case of fire in compartment that is spreading by standard temperature-time curve. In addition, the aim is to substantiate the possibility of using gypsum panels to provide fire resistance of hollowcore concrete slabs. Material statement. The paper reports the results of modeling the process of heat transfer in hollow‐core concrete slab, between compartment space and slab surface and in hollow‐cores. To calculate temperature fields in hollow‐core concrete slab considering nonlinear thermal material properties and radiation heat transfer in the hollow-cores was used finite element model. At addition, the results of finite elements simulations show temperature fields in hollow‐core concrete slab and gypsum panels that installed under concrete slab. Scientific novelty. The paper reports results of theoretic substantiated of possibility of using gypsum panels to protect of hollow‐core concrete slabs considering nonlinear thermal material properties, radiation heat transfer between surfaces and radiation heat transfer in the hollow-cores. The results indicate that using gypsum panels to protect of hollow‐core concrete slabs reduces speed heating of concrete elements to critical temperatures that increase fire resistance of hollow‐core concrete slabs to 20.4 %.

scholarly journals Assessment of radiation heat transfer influence on parameters of temperature fields of various design fuel rods

Vestnik IGEU ◽  
2021 ◽  
pp. 23-31
Author(s):  
V.A. Gorbynov ◽  
S.G. Andrianov ◽  
S.S. Konovaltseva
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Temperature Fields ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Radiation Heat ◽  
Problem Statement ◽  
Fuel Rods ◽  
Fuel Rod ◽  
The Impact

VVER-1000 reactors use cylindrical smooth-core fuel rods. Previously, a model to determe the fuel rod temperature field in a two-dimensional problem statement has been developed and verified. However, modelling assumptions do not consider the influence of variable thermophysical properties, radiation heat transfer, and the opening in the fuel rod on the final parameters of the temperature fields. The impact assessment is an urgent task to improve the economic efficiency of the fuel cycle and the capacity of power units. To develop models and study the features of energy release in nuclear reactors, a numerical package of thermophysical modeling COMSOL Multiphysics software is used. The simulation of temperature fields is performed based on the heat equation with an internal heat source, under the boundary conditions of the second kind at the ends of the fuel rod and the boundary conditions of the third kind on the side surface of the rod. Аn axisymmetric model in two-dimensional problem statement and a three-dimensional model of the fuel rod are developed. The temperature distribution fields are determined by the finite element method. The results of calculations of various design fuel rods are presented. The results have showen that the radiation heat transfer significantly affects the maximum fuel temperature (UO2). The impact degree of variability of thermophysical properties and radiation heat transfer is determined. It was found that the temperature characteristics under different specified conditions have a difference in the range of 15,5–282,0 K (0,8–14,4 %). The developed models are reliable and confirmed by the previously verified model, the characteristics of the fuel assembly used on the VVER-1000 units. The results presented can be used for mathematical modeling of heat transfer processes, both during the modernization of the equipment in operation, and during the development, design, and operation, which will increase the efficiency of electric energy generation at the power unit of a nuclear power plant.

Experimental Study on the Flexural Behavior of Hollow Core Concrete Slabs

2016 ◽  
Vol 857 ◽  
pp. 107-112 ◽  
Author(s):  
L.V. Prakashan ◽  
Jessymol George ◽  
Jeena B. Edayadiyil ◽  
Jerin M. George
Keyword(s):  
Experimental Study ◽  
Flexural Strength ◽  
Failure Load ◽  
Concrete Slab ◽  
Flexural Behavior ◽  
Concrete Slabs ◽  
Control Specimen ◽  
Hollow Core ◽  
The Past ◽  
Core Concrete

Hollow core concrete slabs have many advantages over the conventional solid concrete slabs. The flexural behavior of this type of slabs have not been investigated in detail in the past. The study here addressed this issue by conducting experimental study of four different hollow core concrete slabs along with a solid concrete slab as a control specimen. The load deflection curves were obtained along with the failure load and deflection at the first crack. The effectiveness of the conventional flexural capacity equation in predicting the capacity of hollow core slabs was evaluated. The results from the experimental study were also utilized to do a comparative study among the specimens studied. The study concluded that the conventional flexural strength equation can be used for hollow core slabs too and they have better performance than solid concrete slabs both in terms of load - deflection behavior and serviceability.

scholarly journals Performance of Hollow Core Concrete Slab reinforced by embedded steel tubes

2019 ◽  
Vol 26 (4) ◽  
pp. 17-21
Author(s):  
Yousif Dhari Awad ◽  
Ali Hussein Ali Al-Ahmed
Keyword(s):  
Cross Section ◽  
Concrete Slab ◽  
Load Capacity ◽  
Concrete Slabs ◽  
Total Width ◽  
Horizontal Distance ◽  
Hollow Core ◽  
Steel Tubes ◽  
Ultimate Load Capacity ◽  
Core Concrete

The aims of this paper are gaining additive knowledge about using steel tubes as reinforcement for hollow-core concrete slabs. For this purpose, this paper presents an investigation of how one-way concrete slabs would behave after embedding steel tubes within the cross section. Five concrete slabs were cast, these specimens differ from one another in the horizontal distance (spacing) between the two steel tubes placed within its cross section, steel tubes positioned in the center of the shorter lane of the specimen (width) which is 400 mm, the steel tubes spaced from each other with 4 different configurations, they were 0, 100, 200 and 300 mm. The ratio of the clear spacing between the two tubes and to the total width of the specimen is indicated (s/b) equal to (0, 0.25, 0.5 and 0.75). In addition to one solid slab cast and tested as a reference for the testing results. All five concrete slabs were loaded up to failure by submitting load at one point at the center of the slab. Only one variable was deemed to be considered and checked on this study which is the (s/b) ratio defined earlier. The results exhibit that, using steel tubes as reinforcement increase the first crack load by 12.75% compared to the reference slab, as well as increasing the ultimate load capacity by 59.02% compared to the reference slab. As for the mid-span deflection, the specimens with steel tubes embedded decreased the deflection values up to 47.37 %.

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