STRESS-ANALYSIS OF CONCRETE STRUCTURES SUBJECTED TO VARIABLE THERMAL LOADS

Predicting stress levels caused by thermal effects is a main factor in the correct design of structures; both relate to aspects of the maxim um stress limitation and the durability of constructions. A numerical procedure based on the finite-element method for the stress-strain ana lysis of concrete structures exposed to time- and space-variable therm al loads is presented in this paper. Different environmental condition s can be simulated by means of suitable boundary conditions imposed on the differential equations governing the phenomenon. In particular, t he seasonal and daily variation of external temperature is considered. The presented procedure can also consider the heat generation phenome non, due to the hydration reaction of the cement, which can cause cons iderable temperature gradient and related mechanical stresses, especia lly for thick concrete casting. The stress-strain-thermal analyses of a concrete dam (Sa Stria dam, Sardegna, Italy) and a typical bridge se ction (i.e., box-girder cross section) are carried out to prove the ef fectiveness and reliability of this numerical method in practical stru ctural design.