Investigation on strengthening of CFST members under compression using CFRP composites.

In the present era, the use of CFST members has become quite popular in the construction industry and at the same time, aging of metallic structures and member deterioration have also been often reported. Therefore, actions such as implementation of new materials and strengthening techniques have become essential to combat this problem. It has already been proved that FRP composites significantly improved the strength of reinforced concrete structures. The application of these materials is implemented in the high-performance steel structures. With this aim, an experimental study has been carried out to investigate the suitability of unidirectional CFRP fabrics in strengthening CFST members under axial compression. The size and height of the specimens used in this study are 91.5 × 91.5 × 3.6 mm and 600 mm, respectively. Out of 21 columns, 18 columns were externally bonded by CFRP strips having a constant width of 50 mm with spacing values of 20 mm and 30 mm and the remaining three columns were unbonded. The effect of CFRP layers on the load-carrying capacity of CFST columns was investigated. The strengthened columns exhibited FRP rupture failure due to outward buckling of steel tube. Experimental results also revealed that external bonding of CFRP strips considerably provides the confining pressure to the CFST column and as a result, CFRP-confined columns sustained higher ultimate load and larger axial deformation compared to control column. An analytical model was also proposed herein for predicting the axial load capacity of CFRP-confined CFST columns. The average percentage of difference between the analytical and the experimental loads was found as ±4%. [ABSTRACT FROM PUBLISHER]