Análise de reservatórios cilíndricos apoiados submetidos a ações diretas e indiretas de retração e gradiente térmico

Abstract

Cylindrical concrete storage tanks are largely used for many purposes, such as storage of liquids (water and wastewater, for example) and grains, or even used in projects that have stronger architectural appeal. These structures are often composed of thin walls and are commonly explored worldwide due to their versatility and structural performance. Despite many computational techniques developed for the study of storage tanks, there is a high incidence of structural problems related, for example, to neglecting indirect actions, causing internal stresses that may turn the structural performance impractical, if not considered correctly on the design process. In reinforced concrete storage tanks, some indirect actions must be considered to obtain accurate structural performance, such as concrete shrinkage and thermal gradient effects, in the case of hot liquid storage. This work shows that indirect actions induce great stress loads in the shell elements subjected to purely elastic analyses. Variables such as humidity, in lower values (lower than 70%), may increase tension stresses related to concrete shrinkage that may overcome concrete tensile resistance. On variations of humidity between 60% and 90%, there is a reduction of approximately 89% on strain magnitudes. The studied examples also show that stresses generated by thermal gradient effects are even higher than those generated by the other actions, considering both direct and indirect. On the results of this work, which admits a room temperature of 30oC and a variation of the stored liquid temperature between 60oC and 90oC, there is an increase of 56% on the stress loads caused only by the thermal gradient effects.