Abstract: In order to solve difficulty in quantifying safety state evaluation of highway bridge structure under random operation load, an evaluation method of its performance status based on actual influence line was proposed. Firstly, by clarifying mathematical model of bridge structure under multi axial force and uniaxial force, an optimization analysis model for identifying actual influence line was established using LM, and it was verified theoretically with examples. Then bridge safety state and specific evaluation index were determined according to technical standards of the industry. Finally, with highway prestressed continuous beam bridge as object, actual influence line identification and safety state evaluation were carried out with proposed method. The results show that the deviation between calculated result based on identified influence line and measured one is less than 5%, and safety state can be quickly assessed by action effect amplitude of operation load.

Key words: highway bridge, operation load, safety state, actual influence line, Levenberg-Marquardt(LM) algorithm