AN ANALYTICAL-NUMERICAL STUDY OF THERMAL STRESS IN STRUCTURES OF MASS CONCRETE

Resumo

The construction of gravity dams was a milestone for the development of studies and technological
control of the concrete of mass, because the internal temperature increases began to appear and this generated
cracks. During the process of hydration of the cement particles, there is release of heat, in a process called heat of
hydration, raising internally the temperature of the concrete. This phenomenon causes the internal temperature of
the concrete to differ from the surface temperature, resulting in a thermal gradient, in addition to a slow cooling in
the core of the structures. These temperature changes give rise to thermal stresses, which if not foreseen and
prevented can cause damage to the constructions, when they exceed the capacity of resistance of the concrete.
Thermal stresses take into account the phenomenon of the intrinsic creep in the concrete: there is variation of the
modulus of elasticity over time with the change of temperature. There are a few techniques to try to minimize this
problem, such as building in layers, launching concrete at lower temperatures, use of cements with low heat of
hydration, and more. An effective way of preventing thermal problems in mass concrete is the numerical
simulation, being possible with the mechanism, predict the most critical regions and analyze the probability of
structural damage. In view of the context, this work shows numerical thermal simulations using the Finite Element
Method - FEM, through the ANSYS program for mass concrete structures built in layers. With the numerical
results, the analitical tensions arising from the temperature changes of the bodies are analyzed. It seeks to expose
some of the most favorable conditions in the construction process, identifying possible cracking sites, through
numerical and analytical analysis, contributing to the dissemination of these studies and showing to the community
in interest, constructive methods and methods of analysis that can induce safer construction.