Design method of fire-resistance capacity of reinforced-concrete-filled steel tube column under axial compression

Abstract

Concrete-filled steel tube (CFST) columns are widely used in high-rise and superhigh-rise buildings because of their good mechanical properties, and the fire protection design of building structures must be considered. Under the same conditions, reinforced-concrete-filled steel tube (RCFST) columns show better fire-resistance performance than CFST columns. The theoretical calculation formula of its axial compressive fire-resistance capacity was derived in this study. The current structural design method adopted in China is a partial factor method based on reliability, in which the partial factors at room temperature are generally used for structural design at high temperatures. The strength of materials has greater dispersion at high temperatures, and it is necessary to develop reliability design methods for CFST columns at such temperatures. To consider this change fully, reliability theory was used to obtain the material partial factor at high temperatures. Then, based on the calculation theory of the axial bearing capacity of the RCFST column at high temperatures, a fire-resistant design method for the RCFST column was developed.