Concrete Filled Steel Tube Columns Fire Resistance

Refined finite element fe models are developed for capturing the fire performance of cfst and cfsst stub columns under iso 834 fire.

Concrete filled steel tube columns fire resistance.

These columns are of generic design non proprietary. Columns in the british standard for fire resistant design of steel structures bs 5950 part 8 3 is used to find the limiting temperature of the steel tube in the cft column. A 3 d finite element model was developed to carry out both the numerical heat transfer and nonlinear stress analyses. The fire resistance depends on the effective length of the column the outside dimension of the column either the diameter of a round.

The purpose of this present study is to investigate the fire resistance of cft columns when they are subjected to combined loads. This paper presents a nonlinear thermal stress analysis method for predicting the mechanical behavior and fire resistance of cft columns under eccentric axial load axial load and flexure moment. The fire resistance of concrete filled square steel tube columns cft columns without fire protection under a constant axial load has been previously examined. The use of concrete filled steel tube cfst columns offers an alternative for providing the required fire resistance and load bearing capacity making its use in medium and high rise structures.

However limited work has been done on the resistance of concrete filled steel tube columns subjected to non uniform fire conditions and a calculation method with clear physical meanings is useful to structural engineers. Using the model the fire resistance of circular concrete filled steel columns can be evaluated for any value of the significant parameters such as load column section dimensions column length and percentage of reinforcing steel without the necessity of testing. However most building codes e g ibc 2003 table 720 1 1 and article 720 5 1 4 and asce sfpe 29 99 article 5 2 4 contain formulas specifications to determine the fire resistance of concrete encased columns. A unified method for calculating fire resistance of solid and hollow concrete filled steel tube columns based on average temperature eng struct 71 2014 pp.

This paper introduces simplified design methods for calculating the load bearing capacity of axially loaded concrete filled carbon steel tubular cfst stub columns and concrete filled stainless steel tubular cfsst stub columns. There is an equation to calculate the fire resistance of a concrete filled hss column that comes from asce 29 calculation methods for structural fire prevention and is shown in aisc design guide 19 fire resistance of structural steel framing. If the water can be constantly circulated and renewed fire resistance is essentially unlimited. Concrete filled steel tube columns have been widely applied in modern construction.