A Study on the Temperature Strains in a Concrete Slab Produced by Temperature Variations

Studies on the temperature stresses in a concrete slab (II)

Abstract

The author has already reported on temperature variations in a concrete slab by meteorological action.
This paper deals with temperature strains in the slab produced by these temperature variations.The analysis of the temperature strains was carried out using the theory of elasticity by Timoshenko.
The results are as follows:
1) Temperature strains due to restrained warping (ε_w) produced maximum tensile values of about 13 on the back surface of the slab on fine days.[Fig.4 (B), 5]
2) Temperature strains due to longitudinal restraint (ε_L) were large according to calculations. Cracking is usually safe because of the small restraint ratio.[Fig.4 (A), 6 (A)]
3) ε_w grew to nealy a limited value of tensile strain (ε_lim) during May and June and thus there was the danger of cracking when slab was under strong restraint.[Fig.6 (B) ]
4) Temperature strains due to internal restraint (ε_I) were ordinarily small;however when the temperature of the slab surface fell suddenly, fairly large tensile strains occurred on the surface.[Fig. 4 (C), 6 (B) and 7]
5) The maximum temperature strains (εW_max and εI_max) differ according to the thickness and coefficients of thermal diffusion of the slabs.[Fig.8, 9 and Table 1]