The invention relates to the technical field of
rail transit, in particular to a construction method of a permanent large-span platform layer structure, a steel truss
system is assembled under the
prefabrication working condition, the steel truss
system is formed by splicing a plurality of Bailey steel sheets, and the transversely adjacent Bailey steel sheets are fixedly connected through a transverse splicing structure to form a whole; a profiled steel sheet bottom die is welded on a steel truss
system through a shear connector, a
steel bar truss is welded on the profiled steel sheet bottom die, then concrete is poured to form a
steel bar truss floor support plate, and the
steel bar truss floor support plate and the steel truss system are fixedly connected to form a platform layer structure prefabricated
assembly section of an integral structure. The method has the advantages that the
assembly degree is high, the quality is guaranteed, the construction speed is high, the problem of a large-span structure without columns in the middle can be solved, cast-in-place large-size components and a field complex tensioning process are not needed, and meanwhile the vibration influence of a
train is reduced to a great extent; and the special-shaped steel member is directly connected with the composite floor, so that the integrality is better.