| Fiber reinforced polymer(FRP) has the advantages of light weight, high strength,convenient construction,and has laid a good advantage in the application of steel structure. But the disadvantage of single fiber is obvious,and after strengthening,the ductility is low in the practical application,which restricted the single fiber FRP is widely used in structure reinforcement. To overcome the shortcoming of single fiber and improve the efficiency of reinforcement,hybrid fiber reinforced polymer(HFRP) has gradually becoming a new hot spot in steel structure reinforcement. Previous studies of HFRP mainly focused on the study of the hybrid of two common fibers called CFRP/GFRP,there are few studies on three or more than three kinds of fiber materials.Based on ABAQUS finite element analysis,this paper aims at analyzing the strengthening effect on eccentric compressed square steel tube columns with the idea of three kinds of hybrid fiber which called CFRP/AFRP(BFRP)/GFRP.In this paper, 8 different kinds of HFRP strengthened square steel tube columns with different mixing ratio and number of layers are studied to find the reasonable matching of hybrid fiber, and to obtain the optimal hybrid ratio called the ductility,bearing capacity and economic effect. The method of reinforcement, eccentricity,slenderness ratio and loading level was studied with the influence on the strengthening effect of eccentric compression columns. The research shows: The carrying capacity of CFRP / AFRP(BFRP) / GFRP hybrid reinforced square steel tube column is less than CFRP,under the premise of ensuring the carrying capacity, HFRP shows good ductility performance and can significantly reduce the cost;the reinforcement effect of all-inclusive reinforcement is the most significant;slenderness ratio and eccentricityhave the interaction effect on reinforcement effects of HFRP;before strengthening, the load bearing square steel tube column can be unloaded to achieve the desired effect.Finally, a simplified calculation model of equivalent cross section was put forward.The stability coefficient of the simplified model is calculated by he Perry formula.According to theoretical formula of solid-web bending member by “Code for design of steel structures†to execute calculations. And the result was compared with finite element analysis,the results show that the bearing capacity of most specimens by calculations is in good agreement with the results of finite element analysis. Therefore,based on the finite element analysis results, the simplified model calculation formula was modified with correction factor “kâ€. |
