Spalling Mechanism in Concrete Exposed to Elevated Temperatures
Author
Comsa, Teodora
Term
4. term
Education
Publication year
2013
Submitted on
2013-08-15
Pages
83
Abstract
Dette speciale forklarer, hvorfor og hvordan dele af beton kan skalle af (spalling), når et betonelement udsættes for brand. Det gennemgår den bagvedliggende teori, hvordan svigt kan opstå under forskellige belastningstyper, og hvordan højtydende beton (HPC), selvkompakterende beton (SCC) og højstyrkebeton (HSC) opfører sig i brand på baggrund af forsøgsdata. Rapporten sammenfatter centrale betonegenskaber, der er relevante ved brand, og bruger dem til at opbygge en forenklet fysisk model. Modellen har to dele: en termo-hygral del, der beskriver transport af varme og masse/fugt, og en mekanisk del, der beskriver termiske deformationer og krympedeformationer. På den baggrund udvikles en matematisk formulering og en endimensionel numerisk model. Resultaterne understøtter flere af de indledende teoretiske antagelser, og rapporten afsluttes med konklusioner og anbefalinger til videre arbejde.
This thesis explains why and how pieces of concrete can break off (spalling) when a concrete element is exposed to fire. It outlines the underlying theory, shows how failure can occur under different types of loading, and describes the fire behavior of high-performance concrete (HPC), self-compacting concrete (SCC), and high-strength concrete (HSC) based on experimental data. The report summarizes key concrete properties relevant to fire and uses them to build a simplified physical model. This model has two parts: a thermo-hygral part that represents the transport of heat and mass (moisture), and a mechanical part that represents thermal and shrinkage strains. Building on this, a mathematical formulation and a one-dimensional numerical model are developed. The results support several of the initial theoretical assumptions, and the report concludes with recommendations for further work.
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