Current prescriptive design approaches for structures subjected to extreme temperatures (i.e. IBC 2006 and NFPA 5000) are limited in the evaluation of the overall behavior and stability of building structures under realistic fire loading. First, the Fire Resistance Rating (FRR) values of individual structural members do not provide sufficient information to assess the fire behavior of building structures. It is more imperative to evaluate the thermal and structural interaction between individual components (members and connections) and their influence on the overall fire resistance of the building structure. Second, ASTM E119 temperature-time (T-t) curve used in these approaches does not compare favorably with the realistic T-t relationship for compartment fires. These deficiencies in the current prescriptive design method as well as the need for performance based design guidelines for fire safety have been highlighted by investigation reports on WTC towers and WTC-7 building collapses. This paper presents ongoing work towards the development of a closed-form analytical model to represent moment-curvature-temperature (M-φ-T) behavior of steel columns at elevated temperature under varying levels of axial force and temperature distributions. The model is developed from parametric studies using a fiber-based analytical approach that is calibrated to experimental and finite element results. The development of a closed-form model that considers non-uniform temperature distributions is an essential step in developing tools for practical frame analysis and design methods that do not require high degrees of discretization to capture beam-column limit states.