HABIFU: Numerical study and design proposal for biaxially loaded reinforced concrete columns subjected to fire
Principal researcher:
CARMEN IBÁÑEZ USACH
Team members:
- ANDRÉS LAPUEBLA FERRI
- HÉCTOR SAURA ARNAU
Funding Agency:
Duration: 01/01/2022 – 31/12/2023
Reference: CIGE/2021/002
b) and c) Detail of corner and surface spalling in the RC column
Abstract:
Concrete as a material has an inherent advantage: its good behaviour against fire due to its low thermal diffusivity. This means that, provided an appropriate fire design, reinforced concrete structures can resist for a sufficient time during a fire. This makes their reparation possible ensuring durability and the required resistance capacity. However, to achieve this, it is necessary to have design regulations.
Specifically, for reinforced concrete (RC) columns, the regulations focus mainly on design methods for sections subjected to compression and uniaxial bending loads. However, the functional requirements of the structures generate biaxial bending on the supports due to the loads transferred to them by adjacent beams or slabs (for example, in corner columns). Furthermore, when a RC column is exposed non-uniformly to heating, the sectional distribution of temperatures loses symmetry, just as when the phenomenon of spalling occurs (detachment of parts of the external layer of concrete due to the increase of the pore pressure caused by water evaporation). Both situations cause the appearance of biaxial bending.
Given the complexity that implies the study of biaxial bending combined with the sectional heating, the number of research works found in literature about the fire design of RC columns under these loading conditions is very limited. A review of the literature about the analysis and design models reveals the lack of methods to calculate this type of elements, even in the current codes.
Therefore, the objective of this project is to present a numerical study and a subsequent design proposal to determine the fire resistance of RC columns subjected to biaxial bending. First, a numerical model will be developed and validated. It will be used to generate an extensive numerical data bank from simulations. The analysis of these results will provide trends and conclusions and, based on them, design recommendations will be proposed.