Large-span continuous rigid frame bridge body external prestress loading system

The invention provides a large-span continuous rigid frame bridge body external prestress loading system, and aims to remarkably improve the utilization efficiency of external prestress, save engineering costs and provide effective reserved measures for post-construction deformation control over a midspan of a continuous rigid frame bridge. A bridge body comprises a box girder top plate, a box girder bottom plate, a left side central bearing point partition and a right side central bearing point partition. An external steering support is fixedly arranged on the bottom surface of the box girderbottom plate at the midspan position of the bridge body, and a steering device is mounted at the lower end of the external steering support. An external prestress beam is arranged in a main span range, and is in the shape of a broken line after being steered by the steering machine, and two sides of the external prestress beam separately penetrate through a seamless steel tube which is embedded in the box girder bottom p