Interaction diagrams for ambient and heated concrete sections

Abstract

a b s t r a c tBending moment axial force interaction diagrams are a commonly used tool in any design office. When designing for fire conditions, the large axial forces which develop place an additional importance on the consideration of the interplay between axial forces and moments. This paper presents a new method for calculating the biaxial bending moment/axial force capacity for a general section through the use of the sectional tangent stiffness. A beam-column section subject to fire is assessed, and comparisons made with simplified design tools. It is concluded that derivation of the interaction surface from the tangent stiffness matrix is possible, and that current simplified methods for fire design cannot be assumed conservative.

Efecto del spalling sobre la resistencia a flexión biaxial de pilares de hormigón armado expuestos a fuego.

“…La Figura 3 muestra la buena correlación que existe para los 61 casos validados (Media=0.99, SD=0.17). Para la validación a altas temperaturas bajo flexión uniaxial, las predicciones del modelo se contrastan con las dadas por el modelo de Law y Gillie [18]. El pilar tomado como referencia (300x500mm, 620) está expuesto a la curva ISO 834 [14] [17] observarse como las predicciones de ambos modelos son idénticas.…”

Analytical Study for the Development of Interaction Diagram of the Fire-damaged RC Columns with Varied Heated Areas

“…In addition, this paper presents the derivation of a set of formulas that can be used to estimate the average temperature distribution within the concrete section and the corresponding internal forces. Law and Gillie (2010) reported a new method of creating two-or three-dimensional interaction diagrams under any temperature field based on the tangent stiffness matrix of a section. Among many related researches, effect of heated areas on the structural behaviors of fire-damaged columns for the consideration of real fire situation has been studied limitedly.…”

Structural Engineering and Fire Dynamics: Advances at the Interface

“…Over the duration of the fire exposure, the loading and the capacities of the columns constantly change. Previous work by the authors has demonstrated how the capacity of concrete sections can be rapidly and accurately assessed [46].…”

“…However, it should be noted that it is also possible to analyze shear utilization in a similar manner [48]. Previous work by the author describes the how the interaction surfaces used in these analyses were derived [46].…”