Composite box girder structure and construction method therefor
A composite box girder structure and a construction method therefore. The composite box girder structure includes a box enclosure and an inner core, the inner core includes a thin-walled steel shell, shear connectors, and diaphragms, and the thin-walled steel shell is attached and fixed to an interior of the box enclosure by means of the shear connectors. The inner core and the box enclosure of the composite box girder structure jointly load force, such that effectiveness of the structure in resisting a use load can be improved. The inner core is directly used as an internal template of UHPC, such that rapid bridge construction can be achieved. Further, not only defects of conventional pouring can be overcome, but problems of excessive lateral local stress, overall stability, cross-section distortion and shear bearing capacity of web plates can be solved.
1 . 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 ).
2 . The composite box girder structure according to claim 1 , wherein an interval between every two adjacent diaphragms ( 23 ) is 2 m-10 m.
3 . The composite box girder structure according to claim 2 , wherein the diaphragms ( 23 ) are made of weathering resistant steel, the diaphragms ( 23 ) have a thickness of 0.008 m-0.020 m, and the plurality of diaphragms ( 23 ) are connected by several external prestressing tendons ( 101 ).
4 . The composite box girder structure according to claim 1 , wherein the thin-walled steel shell ( 21 ) is made of weathering resistant steel, and the thin-walled steel shell ( 21 ) has a thickness of 0.008 m-0.020 m.
5 . The composite box girder structure according to claim 1 , wherein the box enclosure ( 12 ) is composed of ultra-high performance concrete plates, and ultra-high performance concrete is reactive powder concrete or ultra-high-performance fiber reinforced concrete having a compressive strength of not smaller than 100 MPa; and the box enclosure ( 12 ) comprises an ultra-high performance concrete (UHPC) bridge deck ( 61 ), a UHPC web plate ( 62 ), and a UHPC bottom plate ( 63 ), wherein the UHPC bridge deck ( 61 ) has a thickness of 0.15 m-0.30 m, the UHPC web plate ( 62 ) has a thickness of 0.10 m-0.60 m, and the UHPC bottom plate ( 63 ) has a thickness of 0.15 m-1.50 m.
6 . The composite box girder structure according to claim 5 , wherein the UHPC bridge deck ( 61 ) is in a shape of a flat plate or a one-way longitudinal rib plate.
7 . The composite box girder structure according to claim 1 , wherein the box enclosure ( 12 ) is internally provided with internal prestressing tendons ( 102 ) in the longitudinal bridge direction.
8 . A construction method for the composite box girder structure according to claim 2 , comprising the following steps:
S 1 , welding thin-walled steel plates to form a thin-walled steel shell ( 21 ), welding shear connectors ( 22 ) to an outer surface of the thin-walled steel shell ( 21 ) at certain intervals, and welding diaphragms ( 23 ) to an inner surface of the thin-walled steel shell ( 21 ) at certain intervals, so as to form an inner core ( 11 );
S 2 , erecting an external form of a box enclosure ( 12 ), and hanging the inner core ( 11 ) in the external form of the box enclosure ( 12 ) and fixing the inner core;
S 3 , forming the box enclosure ( 12 ) through pouring, so as to form the composite box girder structure ( 1 ), and conducting high-temperature steam curing on the composite box girder structure ( 1 );
S 4 , transporting the composite box girder structure ( 1 ) to a mounting position, and erecting and assembling the composite box girder structure on site by using a girder hoisting device, so as to form a box girder bridge body structure; and
S 5 , completing deck paving and ancillary works of the box girder bridge body structure, that is, completing construction.
9 . The construction method for the composite box girder structure according to claim 8 , wherein in S 3 , when the box enclosure ( 12 ) is formed through pouring, the inner core ( 11 ) is used as an internal form.