Abstract: Abstract: In order to study the change law of the flexural performance of concrete beams strengthened by steel bonding after high temperature, a comparative test study was carried out on one unreinforced beam at room temperature, one reinforced beam at room temperature, two unreinforced beams after high temperature and two beams strengthened after high temperature. The distribution law of the cross-section temperature field and the variation law of the bending performance of the specimen were obtained. The research results show that the temperature field of the beam section is unevenly distributed with high outside and low inside. After heating for 60 min and 90 min, the flexural bearing capacity of the test beam is reduced by 7.1% and 10.9%, respectively, compared with that of the normal temperature beam. The reinforced beams were increased by 13.3% and 10.5% respectively. With reference to the calculation formula for the bearing capacity of beams strengthened at room temperature, combined with the simulation results of the temperature field, a theoretical calculation method for the flexural bearing capacity of the bonded steel beams after high temperature is proposed. The calculation results have small errors and meet the actual engineering accuracy requirements.

Key words: Key words: high temperature, steel plate reinforcement, test, finite element, theoretical calculation