The Study Of Mechanical Behavior Of Reinforced Steel Member For Resistance To Buckling

Reinforcing concrete structure with FRP has been widely used, but reinforcing steelstructure with FRP has just started, and it aroused wide public concern. FRP has goodanti-corrosion performance, high strength and good durability, so in many conditions FRP hasadvantages to traditional strengthening methods. In the2008snow disaster in the south, manyelectricity transmission tower structures destabilized and collapsed, and how to reinforce toprevent buckling became an urgent problem. This paper mainly studied steel shotcrete andtwin symmetry steel structure (take the joist steel for example).The first set of experiments contain5joist steel members of which slenderness ratiois105and4joist steel members of which slenderness ratio is175. In the experiment, the set of105slenderness ratio contains a member not strengthened, and the other four are strengthenedwith FRP in different ways, and the bearing capacity of members increases about20%-30%.The loads of the unreinforced members fall fast after reach the peak load, but the loads of thereinforced105slenderness ratio members appear slow rise. The loads of the reinforced175slenderness ratio members fall gently, but the range is small. This shows that FRPreinforcement has well effect in improving no matter bearing capacity or ductility.The second set of experiments contains4tension-compression reciprocating tests forsteel shotcrete, and the purpose is to study the hysteretic behavior, compare the improvementof bearing capacity and ductility and find factors that influence the effect of FRPreinforcement. The first member is reinforced only with FRP pipe, the other three are windedby fabric outside the FRP pipe. The results show that the members reinforced with unrippedpipe have better ductility, because the integrity can be fulfilled. Compared with the firstmember, the tensile bearing capacity of the later three is not improved, but the maximumpressure bearing capacity improves about50%. The reinforcement effect is obvious, but thereare also insufficient. The energy dissipation of the steel shotcrete reinforced with FRP is notthat good.In reinforcing steel components methods, many different kinds of strengthening methodsare used to contrast the influence of different methods. Cyclic load steel shotcrete reinforcedwith FRP and the results show that the mechanical behavior of reinforced member is better.For twin symmetry joist steel, the reinforced member shows better ductility and higher bearing capacity. After the steel members are reinforced, the failure mode has changed. Forsmall slenderness ratio members, generally there will appear local failure in the ends, but forbig slenderness ratio members there will primarily appear the whole buckling phenomenon.