flat hinge;  nonlinearity;  Resistance coefficient;  Iterative algorithm

The force analysis of the flat hinged arch bridge structure belongs to the boundary nonlinear mechanical problem, and the force analysis of some current methods is not clear, and the flat hinged arch bridge such as variable section and complex shape section cannot be calculated. In view of this situation, a new method for determining the resistance coefficient K of flat hinge section is proposed, an iterative algorithm for calculating the internal force of flat hinge arch bridge is established, and an example calculation is carried out, and the research results show that this method is applicable to arch bridge structures with arbitrary flat hinge and arbitrary shape cross-section.