Abstract:In order to study the influence of transverse component layout and section design on the force balance of three main trusses, taking the long-span (160 m+465 m +160 m =785 m) steel truss continuous girder bridge of Sanguantang Bridge in Ningbo as an example, the steel truss girder model is established by using the software of MIDAS Civil to analyze and compare the static effects of bearing reaction, axial force and displacement of the main truss structure under the symmetrical loading and unbalance loading. The internal force distribution characteristics of the main tree-truss continuous steel truss girder bridge are obtained.