Maintenance Project Of T Beam Of Highway Bridge

After years of operation, bridges have gradually developed different degrees of diseases, mainly manifested in: cracks in the upper structure of the main and approach bridges, local apparent defects in the upper and lower structures, local water seepage and whitening and other diseases, which affect the durability of the bridge. Therefore, in order to ensure the durability of Yongning Yellow River Highway Bridge, its existing diseases must be repaired. Aiming at the problem of insufficient thickness of the protective layer of the T-beams of the Hexi and Hedong approach bridges of the original bridge, this paper designs a reinforcement scheme of pasting two-way carbon fiber mesh + sprayed polymer mortar at the horseshoe position of the T-beam to improve its durability.

Superstructure T beam

According to the field survey, combined with the bridge inspection report, there are longitudinal cracks and a small amount of web oblique cracks in the prefabricated T-beam of the west approach bridge of the original bridge. There are a few vertical cracks in the diaphragm, and the maximum vertical crack width is 0.3mm. At the same time, there are damages, exposed tendons, hollowing, cracking and other diseases, and the thickness of the protective layer at the bottom of the horseshoe of some T beams is insufficient, and the stirrup marks are obvious.

substructure piers

According to the field survey, combined with the bridge inspection report, the overall condition of the substructure of the west approach bridge of the original bridge is in good condition, with a small number of network cracks, vertical cracks, honeycomb pitted surface and other diseases.

Material selection

(1) The fiber precursors used in carbon fiber composite materials must be continuous fibers, the main mechanical properties of carbon fibers should meet the regulations, the tensile strength M 4 900MPa, and a raw material report should be issued.

(2) The width of a single bundle of carbon fibers (horizontal and vertical) is 2mm, the spacing is 20mm, the ultimate breaking force must be greater than 3200N, and the elongation is not less than 1.3%.

(3) CFN200/200 bidirectional carbon fiber mesh is used for the carbon fiber grid, and the same brand of wet sprayed polymer mortar is used for the matching mortar.

(4) The fiber mesh needs to be specially coated in the factory to meet the requirements of fire protection and anchoring.