Long-span half-through arch bridges with outward inclined ribs have beautiful appearances and are widely used in bridge engineering.Different from the normal arch bridges

the arch ribs of this type of bridge are not perpendicular to the main girders.Meanwhile

the transverse connections between two arch ribs are relatively weak.The above conditions make the mechanical properties of the bridge become more complicated than the traditional one.In this paper

an extroversive half-through arch bridge with main span of 168 m was taken as an example to analyse the critical joints' mechanical properties.In the analysis

finite element model method was used.Firstly

a beam finite element model of the whole bridge was used to obtain the forces and moments of the critical joints.Secondly

refined 3D solid finite element models of the critical joints were used to analyse the stress and deformation.Research results shown that

the stiffness of the structure is large and the deformation is small;the outward inclined ribs make the critical joints' mechanical properties become more complex;for the joints

there are both bending moments in and out of plane;the complex structure of the bridge and spatial stress-strain state are the key factors which induced the stress concentration phenomenon of the critical joints;In the design

corresponding measures should be taken to avoid stress concentration.