Study on Mechanical Properties of Main Girder of Continuous Box Girder Bridge Strengthened By A Cable-Stayed System

Abstract

The local stress concentration of the main girder during the tensioning construction of the continuous box girder bridge strengthened by the cable-stayed system is more prominent, which may lead to the sudden damage of the structure. Therefore, this paper studies the key section stress and deformation of the main girder in combination with the real bridge test. The results show that the maximum tensile and compressive stress increase of the main girder appears at the root floor and midspan floor; The tensile action strengthens the compressive stress between the anchorage point of the long cable and the anchorage point of the short cable to the top of the pier, which releases some of the compressive stress across the mid-slab, improves the stress state of the main girder, and improves the shear load of the main girder ability; With the increase of the cable force, the main tensile stress of the web in the anchoring area first increases and then decreases. The lifting amount of the midspan section of the main girder accounts for 20.06% of the total deflection, and the effect of the cable-stayed system on improving the deflection of the main girder is obvious.