Abstract
This paper presents a general procedure based on fracture mechanics models in order to analyze the level of cracking and structural safety in reinforced concrete elements at early ages, depending on the stripping time. Our procedure involves the development of a thermo-mechanical numerical model based on the finite element method that accounts for the change in the mechanical properties of concrete with time. Moreover, fracture mechanisms are analyzed by means of a material damage model, which is characterized via specific experimental results obtained for standard specimens and notched beams under three-point bending testing. The loading conditions are both thermal and mechanical, and are obtained from the hydration process for a given concrete dosage. The presented methodology allows for the determination of the optimal stripping time, whereas it helps assessing the analysis of the cracking and the stress states of the elements under consideration. A practical application, namely the analysis of a retaining wall, is used to validate our methodology, showing its suitability in engineering practice.
Highlights
1 Introduction Concrete mechanical behavior at early age is characterized by the development of low mechanical properties and the appearance of thermal stresses generated by temperature gradients from the heating process during the cement hydration (Wang and Luan 2018)
We present a methodology for the analysis of early age cracking in large concrete structures by implementing the aforementioned models with the finite element method (FEM)
6 Conclusions One of the main problems in the construction of large concrete structures is early age cracking, a phenomenon promoted by the exothermic reaction resulting from cement hydration, which rises the temperature in the mix producing temperature gradients that eventually generate thermal stresses
Summary
Concrete mechanical behavior at early age is characterized by the development of low mechanical properties and the appearance of thermal stresses generated by temperature gradients from the heating process during the cement hydration (Wang and Luan 2018). In order to characterize the material response with the use of the CDP model, it is necessary to provide the material elastic constants (i.e., Young’s modulus, E , and Poisson’s ratio, ν ), coefficient of thermal expansion ( α ), uniaxial tensile behavior in terms of stress-opening (e.g., a linear function defined by the tensile strength, ft , and fracture energy in mode I, GF ) and damage-opening laws, uniaxial compressive behavior in terms of stressinelastic crushing strain and damage-inelastic crushing strain laws, and the Drucker–Prager associated parameters (i.e., dilation angle, eccentricity, surface shape parameter, and compressive biaxial to uniaxial strength ratio) This model is available in the commercial software Abaqus (SIMULIA Corp 2016) and more details on its implementation can be found in (Montero-Chacón et al 2015, 2017). The heat dissipation by convective mechanisms through the outer surface can be accounted for
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Concrete Structures and Materials
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
