The bearing capacity of reinforced concrete（RC） beams strengthened with near-surface mounted carbon fiber reinforced plastic（CFRP） and pre-stressed helical rib bar can be increased significantly in comparison with the un-reinforced beams.Firstly

this paper simply presents the bearing capacity results of seven reinforced concrete beams strengthened with near-surface mounted CFRP and pre-stressed helical rib bar

and then

the failure modes of strengthened beams including multiple materials and interfaces are analyzed systematically.Compared with the possible failure modes

the failure modes and the failure mechanism of the strengthened beams are analyzed.The analyzing results indicate that the bearing capacity of strengthened beams are seriously influenced by the interfaces

different failure modes correspond with the section total force of the strengthening material

and the judgment of failure interface should be careful

otherwise

the error of calculating results would be very great.