Study On The Eccentric Compression Capacity Of Variable Cross-section Box Compression Strengthened With FRP

Although the application of fibre reinforced polymer(FRP) on strengthening ofconcrete structures have been reported wildly, there are relatively few application tosteel structures, and the present researches of steel structure strengthened with FRP bothat home and abroad are mainly limited to uniform cross-section members, however, thevariable cross-section members reinforced with FRP are barely involved.The shell-spring-shell finite element model is builded in the paper, and theanalysis and study of variable cross-section box eccentric compression membersstrengthened with FRP under the different influencing factors of repair effectiveness arediscussed, such as tapering ratio, slenderness ratio of column, the number of FRPlayers, the modulus of elasticity of FRP and the thickness of FRP,meanwhile, theload-displacement curves, the ultimate loading of column and the deformation arepresented.Parameter analysis results indicate that ultimate bearing capacity of components isdecreased with the tapering ratio and slenderness ratio increasing, and when the loadeccentricity is smaller,the lowering is more obvious.With the FRP layers increasing,theultimate bearing capacity of reinforced members is improved a little,the reinforcementeffect is not obvious.The reinforcement effect indexR fis increased with the tapering ratio, themodulus of elasticity of FRP and the thickness of FRP increasing, the FRPreinforcement effect is significant. The high modulus and thicker FRP is used tostrengthen the biger tapering ratio members as much as possible in design.In certainslenderness ratio range, the reinforcement effect index increases with theincreasing of the slenderness ratio, the FRP reinforcement effect is better, when themember reaches a critical slenderness ratio, the reinforcement effect index decreases with the increasing of the slenderness ratio, FRP strengthening effect is not obvious.With the modulus of elasticity of FRP and the thickness of FRP increasing, thereinforcement effect index is increased, and then the FRP reinforcement effect isbetter.Combination of Technical Specifications for Steel Structure Reinforcement(CECS77:96), Code for Design of Steel Structures (GB50017-2003) and PortalFrame Light Steel Structure Housing a Technical Specification (CECS102:2002), adesign formula for variable cross-section box members subjected to eccentriccompression bearing capacity is presented.Then the proposed formula is amended bythe influence of each parameter on calculation results.