Composite box girder structure and construction method therefor

A composite box girder structure, comprising a box enclosure (12) and an inner core (11), wherein the inner core (11) comprises a thin-walled steel shell (21) and shear connectors (22), and the thin-walled steel shell (21) is attached and fixed to an interior of the box enclosure (12) by means of the shear connectors (22);

• the inner core (11) further comprises diaphragms (23), the diaphragms (23) are fixed to an inner side of the thin-walled steel shell (21) in a cross-sectional direction of the inner core (11), the plurality of diaphragms (23) are arranged at the inner side of the thin-walled steel shell (21) in a longitudinal bridge direction;
• when the span of the bridge is small and bearing capability is required to be low, the n-shaped thin-walled steel shell (21) partially covers and is attached and fixed to an inner surface of the ultra-high performance concrete box enclosure (12);
• the n-shaped diaphragms (23) are fixed to the inner side of the n-shaped thin-walled steel shell (21).