Seismic Behaviors of Concrete Beams Reinforced with Steel-FRP Composite Bars under Quasi-Static Loading

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.

Fragility Curves for RC Structure under Blast Load Considering the Influence of Seismic Demand

“…For this reason, it is possible to assume that the dynamic behavior of the structure under a uniform blast load pressure can be represented by an equivalent SDOF system. Push-over analysis [29][30][31][32] can produce the force-displacement diagram known as a capacity curve. From this capacity curve it is possible to obtain an equivalent bilinear force-displacement diagram that represents the SDOF constitutive behavior [33][34][35] as shown in Section 4.2.…”

Experimental Investigations of the Strengthening Effects of CFRP for Thin-Walled Storage Tanks under Dynamic Loads

“…Consider a laminate made of n plies, as shown in Figure 4. Each ply has a thickness of t k and the thickness of the laminate is h. The in-plane properties of the CFRP-reinforced steel lamination can be determined using Equations (6)- (12). Table 5 shows the resulting calculated mechanical properties of the CFRP-aluminum lamination.…”

“…The mechanical properties of the CFRP-aluminum lamination. In Equations (6)- (12), (σ x , σ y , σ xy ) and (ε 0 x , ε 0 y , ε 0 xy ) are the principal stress and mid-plane strain components associated with the x-y plane, respectively; t c is the thickness of the CFRP layer; t a is the thickness of the aluminum; and A ij denotes the components of the inverse matrix A ij . Figure 5a shows the test ring and specimen configurations.…”

“…In addition, the reparation process can interrupt the business and can cause damage to storage materials during the structural renovations. Recently, the use of carbon fiber reinforced polymers (CFRPs) to strengthen concrete beams and columns has been popular because CFRPs have many advanced characteristics, such as having high strength and corrosion resistance, and being lightweight [12][13][14][15]. Moreover, the use of CFRPs to improve the load-carrying capacity and performances of steel structures has also attracted many researchers [16][17][18][19][20][21][22].…”

“…Plane stress conditions for a thin plate (a) and a CFRP-reinforced aluminum lamination (b).In Equations (6)-(12), (x, y, xy) and ( are the principal stress and mid-plane strain components associated with the x-y plane, respectively; tc is the thickness of the CFRP layer; ta is the thickness of the aluminum; and ' ij…”