###### Abstract  
Steel-fiber reinforced polymer (FRP) composite bar (SFCB) is a new composite material with good corrosion resistance and designable post-yield stiffness. Substitution of steel bar with SFCB can greatly increase the durability and ultimate capacity associated with seismic performance. First, the method and main results of the experiment are briefly introduced, then a simplified constitutive model of composite bar material was applied to simulate the seismic behaviors of the concrete beams reinforced with SFCBs by fiber element modeling. The simulation results were found to be in good agreement with test results, indicating that the finite element model is reasonable and accurate in simulating the seismic behaviors of beams reinforced with SFCB. Based on the numerical simulation method, a parametric study was then conducted. The main variable parameters were the FRP type in composite bars (i.e., basalt, carbon FRP and E-glass FRP), the concrete strength, basalt FRP (BFRP) content in SFCBs and shear span ratio. Seismic behaviors such as load-displacement pushover curves, seismic ultimate capacity and its corresponding drift ratio of the SFCBs reinforced concrete beams were also evaluated. The results showed that (1) the fiber type of the composite bar had a great impact on the mechanical properties of the beam, among which the beam reinforced with BFRP composite bar has higher seismic ultimate capacity and better ductility. With the increase of the fiber bundle in the composite bar, the post-yield stiffness and ultimate capacity of the component increase and the ductility is better; (2) at the pre-yield stage, concrete strength has little influence on the seismic performance of concrete beams while after yielding, the seismic ultimate capacity and post-yielding stiffness of specimens increased slowly with the increase in concrete strength, however, the ductility was reduced accordingly; (3) as the shear span ratio of beams increased from 3.5 to 5.5, the seismic ultimate capacity decreased gradually while the ultimate drift ratio increased by more than 50%. Through judicious setting of the fiber content and shear span ratio of the composite bar reinforced concrete beam, concrete beams reinforced with composite bars can have good ductility while maintaining high seismic ultimate capacity. steel-fiber reinforced polymer composite bar; concrete frame beam; seismic behavior; finite-element model +
Footnote †: journal: Applied Soft  
evolves into serious damage if effective measures are not taken. To enhance the anti-corrosion properties of steel bars, various techniques have been proposed. Fiber reinforced polymer (FRP) is a non-metal material that has evolved to an effective substitution for steel rebar in severe environments. Furthermore, FRPs can be suitable for use in extreme conditions such as fire or blast loading [1; 2]. Because of the highly desirable properties of FRP, such as high strength, light weight and high anti-corrosion, the application of FRP as reinforcement in concrete structures has been growing rapidly [3; 4; 5; 6]. A potential application of FRP reinforcement is in reinforced concrete (RC) frames. However, due to FRP's predominantly elastic behavior, FRP-RC members exhibit low ductility and energy dissipation, thus restricting its application in construction [7; 8]. In recent years, it has been reported that RC members reinforced by hybrid conventional steel bars and FRP bars can improve their seismic performance [9; 10; 11]. A hybrid rod made with FRP skin over a steel core was first proposed by [PERSON] et al. [12] to achieve good anti-corrosion performance for concrete beams, where the FRP skin is made of braided epoxy-impregnated aramid or vinylon fiber. Combining the advantages of FRP and steel bar, the new composite bar is expected to have high strength, high elastic modulus, good ductility and anti-corrosion properties. The factory-produced steel-FRP composite bar (SFCB) was proposed by [PERSON] et al. [13].