Damage integrated performance modelling of steel plate girders at elevated temperature

The design of thin-walled steel plate girder cross-sections is considerably governed by the web instabilities driven by the phenomenon called shear buckling. Change of web geometry due to the partial loss of material in the form of local corrosion of web panels or the loss of mechanical properties caused by elevated temperature amplifies the shear buckling behaviour of girders leading to the loss of ultimate shear capacity significantly. Moreover, steel plate girders with low fire resistance due to their high thermal conductivity and thermal expansion are equally vulnerable to corrosion when exposed to detrimental environmental conditions. This research investigated how the standard fire resistance and elevated temperature buckling resistance of steel plate girders can be affected by the corrosion induced structural deterioration. An advanced Finite Element (FE) modelling procedure was used to evaluate the behaviour of steel plate girders shear behaviour. Some commonly encountered corrosion patterns reported in the literature were simulated. Results revealed both the position and the severity of damage is important for the fire resistance degradation resulting from the reduction in the shear capacity of thin-walled steel girders. Results were also compared with the EN 1993-1-5 design guidelines to achieve a modified formulation. This comparison revealed that depending upon the position and the extent of the corrosion level, the web contribution factor to the shear buckling resistance of a steel plate girder can fall below the Eurocode design guidelines.