Steel-concrete composite beam

The invention discloses a steel-concrete composite beam and belongs to the field of bridge and civil construction. The composite beam mainly comprises a steel beam, a concrete board and shearing force connecting pieces for connecting the steel beam with the concrete board. A body of the steel beam is a steel box, the cross section of the steel box is in a non-closed isosceles trapezoid shape with a lower opening, and the opening is symmetrically located in the middle portion of the bottom edge. Main components of the steel box can be manufactured through a cold press molding process, stiffening ribs can be welded to the inner side of a web, and a reinforcing steel board or a supporting cushion board can be welded locally. A transverse partition board can be arranged in the steel box in the longitudinal direction of the steel beam, and prestressed reinforcing steel bars can be arranged in the concrete board as well. The steel beam of the composite beam can be made of weathering steel. The composite beam is con