Theoretical Calculation Formula of Equivalent Thermal Conductivity for Reinforced Concrete Slab
Reinforced concrete structure is a kind of composite material,and its thermal conductivity is affected by factors,such as reinforcement ratio and steel bar direction.The reinforced concrete slab was regarded as a two-phase composite material composed of steel bar and concrete.Based on the series and parallel equivalent models and referred to the reinforcement layer hypothesis in the layered combined finite element model,the calculation formulas of equivalent thermal conductivity in different heat flow directions were obtained.The rationality of the formula was verified by experi-ments.The effects on equivalent thermal conductivity of the orientation of reinforcing bars,reinforcement ratio,slab thickness,and the ratio of thermal conductivity between concrete and steel on the thermal conductivity of reinforced con-crete slabs were analyzed.It is shown that the results of the equivalent thermal conductivity is well agreed with result of the experimental.The equivalent thermal conductivity of reinforced concrete slab in three directions increases with the in-crease of reinforcement ratio,and the influence on the axial equivalent thermal conductivity of steel bar is the most signifi-cant.In the case of the same reinforcement,the two equivalent thermal conductivity coefficients perpendicular to the axial direction of the steel bar increase with the increase of the ratio of thermal conductivity between concrete and steel.The e-quivalent thermal conductivity of the steel bar increases with the increase of the plate thickness,and the increase of the plate thickness has little effect on the equivalent thermal conductivity in the other two directions.The established equiva-lent thermal conductivity calculation formula can be equivalent the reinforced concrete slab to the homogeneous material for simplifying the heat conduction analysis.
reinforced concrete slabequivalent thermal conductivityreinforcement layer equivalentreinforcement ratiodirection of steel bar
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