Using SAP2000 software and plastic hinge theory

the dynamic elastic-plastic performance analysis of a long-span public structure is carried out under different earthquake ground motions.In the analysis both geometric and material nonlinear effects are taken into consideration.The plastic hinge distributions

and the deformation mode and failure patterns

and the ductility performance are obtained.Based on the failure forms the seismic performance under strong seismic action is evaluated.The results show that:the structure failure type is that the key chords and webs in the curvature change position and near the bearings gradually enter different stages of the plastic hinge and form a local plastic hinge concentrated area

and finally lead to the structure failure;Under seismic ground motion

the assessed failure peak value of the earthquake acceleration is 595 gal and its corresponding maximum vertical displacement is 1/207 of the span

the structural ductility coefficients in each direction is greater than 4

the plastic deformation ability is great

which could meet the requirements of the safe work performance of earthquake refuge in the area with seismic intensity Ⅷ.