Simplified Analysis of Flat-Plate Buildings During Fire Exposure
Abstract
In response to the rising adoption of performance-based design in modern standards, there is a growing demand for practical and efficient methods to effectively model and analyze reinforced concrete (RC) structures. These methods should be cost-effective, time-efficient, and maintain high accuracy, addressing the needs of practitioners in the field. Elevated temperatures caused by fires degrade the mechanical properties of concrete and steel bars and introduce new strains, including thermal and transient strains.
An RC flat plate slab is not entirely free to move during temperature variations, which is attributed to the continuity of the slab and its interaction with supporting columns. The semi-rigid connections between the slab and columns result in additional stresses in the slab and columns due to the thermal strains. Simplified methods for predicting the capacity of flat slab plates and assessing the global response of entire flat plate structures exposed to standard and actual fire incidents are currently unavailable.
This Ph.D. thesis introduces simplified methodologies that facilitate applying performance-based design for flat slabs exposed to fire. The thesis contributions encompass converting a real fire scenario to an equivalent duration of the standard fire, assessing the thermal behaviour of a flat slab section, evaluating the flexural behaviour of a flat slab section, determining flexural and shear capacities of flat slab section, providing clear guidelines for modelling flat slab buildings exposed to fire using the finite element method, and presenting two approaches to analyze flat plate buildings during fire exposure. The two presented approaches are based on frame and grillage analysis methods. Validation throughout the thesis was conducted by utilizing research conducted by other researchers and comparing the predictions of the finite element method and the simplified approaches.