Analysis of fire resistant response for steel staggered-truss system under different fire protection

A sub-truss is chosen from a typical staggered truss and protected by different kinds of fire protection modes such as intumescent coatings,thick fire retardant coatings,locally protected method,mixed fire protection and so on.And the whole elastic-plastic structural response process in fire is numerically analyzed using the finite element method.Both the effects of different fire protections and the casualties of the different structural responses are studied,for the purpose to obtain an optimizing fire protection strategy which considers both economy and practicality.The result indicated that: the various fire protection methods will lead to the differences in temperature increases which might make the interaction of internal forces change notably.The tendency of the internal force of the components is more or less the same when the structure has no fire protection or under normal uniform fire protection.The internal force distribution could be optimized when locally protected method is adopted,and the places of the truss emerging the plastic deformation in fire vary greatly.And the proposed local fire protection can make some promotions on the fire resistant capacity of the structure compared with the unprotected cases,but the effect is not so effective.The fire resistant capacity of the structure can be improved dramatically when the fire protection on the components,which appear plastic deformation easily,is enhanced based on the former intumescent coatings method.