MODELING NON-STATIONARY TEMPERATURE FIELDS WHEN CONSTRUCTING MASS CAST-IN-SITU REINFORCED-CONCRETE FOUNDATION SLABS

Abstract

Introduction: Due to hydration heating and heat exchange with the environment during hardening, mass cast-in-situ reinforced-concrete structures exhibit non-uniform heating, which can result in early cracking and make the structures unsuitable for further use. One of the main risk factors for early cracking is the temperature difference between the center and the surface of the structure. Purpose of the study: We aimed to study how such factors as the ratio of dimensions, heat transfer conditions on the surfaces, concrete recipe, pauses during concreting and their duration affect the maximum temperature difference between the center and the surface of the structure. Methods: In the course of the study, we applied finite element modeling in one-dimensional and three-dimensional cases using the software in the MATLAB environment that we developed earlier. Results: We established that the most significant risk factors for early cracking are heat exchange conditions on the top surface, structural thickness, and the heat release rate of concrete. Verification and validation of the model were performed based on experimental data and by comparing it with a numerical solution in the ANSYS software.

Keywords

• mass reinforced-concrete structures
• foundation slab
• cracking
• temperature field
• finite element method
• internal heat sources.