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 maximum stress limitation and the durability of constructions. A numerical procedure based on the finite-element method for the stress-strain analysis of concrete structures exposed to time- and space-variable thermal loads is presented in this paper. Different environmental conditions can be simulated by means of suitable boundary conditions imposed on the differential equations governing the phenomenon. In particular, the seasonal and daily variation of external temperature is considered. The presented procedure can also consider the heat generation phenomenon, due to the hydration reaction of the cement, which can cause considerable temperature gradient and related mechanical stresses, especially for thick concrete casting. The stress-strain-thermal analyses of a concrete dam (Sa Stria dam, Sardegna, Italy) and a typical bridge section (i.e., box-girder cross section) are carried out to prove the effectiveness and reliability of this numerical method in practical structural design.