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Basic Research on CFRP Reinforcement of Steel Short Columns

Takeshi Miyashita

In japan, most of the seismic retrofitting of steel short columns uses a backing plate method using high-strength bolts, which has some problems. On the other hand, Carbon Fiber Reinforcement Polymer (CFRP) method which solves that problems. In this study, in order to conduct a basic study for seismic retrofitting and the methodology of this research is know to reinforcing effect when reinforced with CFRP sheet. In this experiment, 13 specimens with different webs and flanges were reinforced in 3 cases. And two types of sheets are used in cases including vertical, horizontal. The final state of each test piece without reinforcement was judged by the load bearing capacity test, and the surface where local buckling occurred was reinforced by CFRP sheets.
In results, we got vertical displacement, fracture condition, maximum load, buckling load, strain. From vertical displacement, the increasing tendency of the load in the elastic region with no reinforcement and with reinforcement was almost the same as the theoretical value. It was also found that the yield load at the time of no reinforcement was exceeded by reinforcement.
The same results were seen for the maximum load and the buckling load, and the seat reinforcement showed a sufficient effect. And it was also found from all the results that the value of the test piece reinforced with the horizontal sheet was higher than the value of the other test pieces.
Summarizing each study, it can be said that reinforcing a rectangular cross-section column with a CFRP sheet has a sufficient effect on maximum load, buckling load, stress reduction. By using, CFRP sheets in the vertical and horizontal direction, the method is more effective than by using CFRP sheets in the vertical direction. And even if reducing the CFRP sheets in horizontal direction, it is still showing good results