Volume 7, Issue 1 (January 2010)
Predicting Fire Behavior of Composite CFT Columns Using Fundamental Section Behavior
This paper presents the development and verification of a fiber-based analytical approach for predicting the behavior of concrete filled steel tube (CFT) columns subjected to constant axial load and standard fire loading. The approach consists of three parts: (1) Two-dimensional heat transfer analysis, (2) section moment-curvature analysis, and (3) column inelastic buckling analysis using modified Newmark’s method. The analytical approach was verified by using it to predict (1) the thermal and structural behavior of CFT column specimens subjected to standard fire tests by different researchers and (2) the fundamental moment-curvature behavior of CFT beam-column specimens subjected to special (non-standard) fire tests conducted by the authors. The analytical approach predicts the fundamental moment-curvature behavior of CFT beam-column specimens and the standard fire behavior of CFT column specimens with reasonable accuracy. The analytical results also compare favorably with the overall behavior and stress states predicted by three-dimensional finite element analyses conducted earlier by the authors. The fiber-based analytical approach is recommended for modeling and predicting the standard, non-standard, or realistic fire behavior of CFT columns and beam-columns under various loading, heating, and boundary conditions.