Temperatures and stresses due to cement hydration on the R/C foundation of a wind tower-A case study

摘要

A numerical prediction of temperatures and stresses on a R/C foundation of a steel wind tower, and during the first weeks after casting, is presented in this paper. The thermo-mechanical methodology adopted for this kind of analysis is introduced first, describing the thermal field engendered in concrete by the heat released during cement hydration, the aging laws that reproduce the growth of the mechanical properties during the early stages and the concrete stresses evaluation. Attention is thereafter focused on the application that is the aim of this work, with regards to the following issues: (i) characterization of the heat generated by the concrete mixture, (ii) estimation of the parameters and properties involved in the numerical model and (iii) the thermal influence of the granite massif on top of which the R/C foundation relies. Field measurements of temperatures within concrete are compared with predictions from a 2D thermal analysis, and the resulting stresses, with special regards to the anchorage zone of the wind tower onto the foundation, are discussed in detail. Some comments concerning the thermally induced cracking risk on the foundation are put forward at the end.