A structure for last prestress application of steel frame

The utility model discloses a structure for last prestress application of steel frame, wherein, including upper chord, lower chord, web member and setting at the U template of lower chord with the web member junction, the bottom of U template is equipped with two annular pipe, annular pipe sets up with the U template is integrative, be equipped with the connecting pipe between the annular pipe, threaded connection is passed through with the connecting pipe in inserting annular pipe in lower chord follow U template both ends, two lower chords are close to simultaneously or part simultaneously about making through the rotation connecting pipe. The utility model discloses set up the U template on the node of lower chord, exert appropriate reversed stress through the connecting pipe on the U template to the lower chord, make the lower chord under the prerequisite of guaranteeing original bearing capacity, effectively utilize the material, dwindle the size in cross -section, not only lightened self weight, still r