A large-space grid structure of steel is often used as a roof of a building with a dense occupation. Once the structure collapsed

it may cause heavy casualties and property losses.Therefore

it is necessary to launch further research on its performance of fire-resistant.In this paper

a fire simulation of the facto- ry workshop was carried out with FDS to obtain the time-temperature curves.On this basis

the coupled thermo-mechanical system was analyzed with the finite element software ANSYS

which can supply the in- ternal forces and displacements of a grid structure when fire occurred in different places.The results indi- cate:temperature field calculated with the computer simulation is more consistent with the real situation than with the ISO834 standard heating curve.A fire occurred in the middle of the structure is more dan- gerous than one on the edge of the structure.When some bars yield or retreat to work

the stresses will be redistributed in the whole structure

the farther away from the fire source

the less the variation of bar stress.Conclusions in this paper could offer a useful reference for future fire-resistance designs and rescue of this type of structure.