Evaluation of some methods for calculating thermal stresses during concreting of massive reinforced concrete foundation slabs
Abstract
Evaluation of some methods for calculating thermal stresses during concreting of massive reinforced concrete foundation slabs
Incoming article date: 06.06.2022The relevance of modeling the temperature regime and the stress-strain state in the early period of the construction of massive monolithic reinforced concrete structures is shown. Some data are given on the temperature and time parameters of the formation of temperature fields in structures with a surface modulus from less than 1.1 to 2.4 from concrete classes from B25 to B70, both fast and slowly hardening. Based on the results of processing numerous data, the quantitative values of the parameters of the heat release kinetics for the proposed dependence are substantiated. A simplified method for calculating thermal stresses is proposed, based on the proposed and substantiated dependences of concrete properties on its degree of maturity, which are confirmed by numerous experimental data, incl. obtained by other researchers. The calculated values of stresses obtained during the construction of a temperature-shrinkage block 20x20x2 m from concrete of fast and slow hardening classes B25 and B45 were compared with some experimental results and modeling data. The conclusion is made about the inexpediency of using concrete of class B45 due to the high risk of cracking in the period of 1.5 - 3 days. When using concrete of class B25, preference should be given to fast-hardening.
Keywords: massive monolithic structures, thermal stresses, cracking, degree of concrete maturity, kinetics