The variation process of the axial force of restrained cross-shaped columns under high-temperature is studied using the computer program SAFIR.The influence law of some parameters on the axial force in restrained cross-shaped columns in fire is examined and a practical calculation method for axial force of restrained cross-shaped columns during fire is proposed in this paper.Simulation results show that:（a） the influence of axial load ratio

axial restraint stiffness ratio

rotational restraint stiffness ratio

load eccentricity ratio

and sectional dimensions on axial force of restrained cross-shaped columns is significant

while the effect of column height

thickness of concrete cover

reinforcement ratio

and strengths of materials is marginal;（b） with the increase of the axial restraint stiffness ratio

the maximum value of the ratio of additional axial force under high temperature to axial force under room temperature（i.e.

axial force variation coefficient in this paper） increases for both concentric and eccentric loading columns

and this trend is more significant for the eccentric loading columns;（c） the maximum value of the axial force variation coefficient of columns without rotational restraint is close to that of columns with rotational restraint

while the effect of non-zero rotational restraint ratio on the axial force variation coefficient is negligible;and（d） with the increase of the axial load ratio

the maximum value of the axial force variation coefficient reduces quickly

this trend is more significant for the eccentric loading columns;and with the increase of the load eccentricity ratio

the axial force variation coefficient improves greatly.Since the restrained actions occur in adjacent elements of practical structures in fire

it is important to make clear the variation of the internal forces in restrained structures under high temperature.