Avaliação das ações térmicas e de retração em uma edificação em paredes de concreto moldadas in loco

Abstract

This research aims to analyse the effects of thermal variations and shrinkage on four walls and the roof slab of a concrete walls casted in place building. Three types of thermal loads have been testeds, a uniform heating and cooling, applieds as deformations equivalents to a thermal variation of +15 ºC and -15 ºC, respectively, and a linear gradiente, equivalent to a thermal difference of 15 ºC between the coldest face and the hottest face of structural elements subjecteds to direct sunlight. The shrinkage was considered as a deformation equivalente to a uniform thermal variation of -30 ºC. The thermal loads and shrinkage were combined with dead and live loads, in accordance with the precepts of ABNT NBR 6118 (2014) and NBR 16055 (2012) standards. The building model was discretized in finite elements with SAP2000 V18 software. Both walls and roof slab were modelled as surface elements. The materials were considered in accordance with NBR 6118 (2014) standard, for a enviromental agressiveness class II, being C30 the compressive strength of concrete. The results indicated that the thermal and shrinkage effects are significant as the analysis for the Limit State of Serviceability on cracking formation, developing tensile stresses above the admisseble for both concrete walls and roof slab. It is evident that the thermal loads and shrinkage could develop pathological manifestations in elements, walls and slabs, when not considered, being necessary to indicate rebars to conter these effects.