Title: Stress-Block Parameters for Reinforced Concrete Beams During Fire Events
Author(s): S.F. El-Fitiany and M.A. Youssef
Publication: Symposium Paper
Appears on pages(s): 1-40
Keywords: Concrete; Elevated temperatures; Sectional analysis; Fire resistance, Stress-block parameters.
Fire safety is a critical criterion for designing reinforced concrete (RC) structures. As new design codes are moving towards performance-based design, analytical tools are needed to help engineers satisfy code criteria. These tools are also needed to assess the fire performance of critical structures. As full scale experiments and finite element simulations are usually expensive and time consuming options for designers to achieve specific fire performance, a simplified sectional analysis methodology that tracks the axial and flexural behavior of RC square sections subjected to elevated temperatures from their four sides was previously developed and validated by the authors. In the first part of this paper, the proposed methodology is extended to cover rectangular beams subjected to standard ASTM-E119 fire from three sides. An extensive parametric study is then conducted to study the distribution of the concrete compressive stresses at different ASTM-E119 fire durations. Based on the parametric study, simple equations expressing the equivalent stress-block parameters at elevated temperatures are presented. These equations can be utilized by designers to accurately estimate the flexure capacity of simply supported and continuous beams exposed to fire temperatures.