Experimental tests and analytical model for reinforced polyvinyl alcohol‐engineered cementitious composite beams in bending

Abstract

Polyvinyl alcohol‐engineered cementitious composite (PVA‐ECC) exhibits strain hardening and multiple cracking characteristics under tension. Its superior tensile behavior may also influence the flexural behavior of reinforced PVA‐ECC beams. This paper investigates the load capacity and failure mode of reinforced PVA‐ECC beams in bending. Seven beams with different tensile reinforcement ratios, including six PVA‐ECC beams and one conventional concrete beam, were tested in the experimental program. The influence of reinforcement ratio on load capacity and failure characteristics was discussed in detail. Test results showed that with increasing reinforcement ratio, the ultimate load of beams was increased, but the failure mode was changed from fracture of PVA‐ECC in the tension zone to crushing in the compression zone, thereby limiting the full development of beam ductility. An analytical model is proposed to calculate the load and the vertical deflection of beams. In the model, the tension‐stiffening effect of reinforcement after cracking of PVA‐ECC is considered by defining the bond–slip relationship of reinforcement embedded in PVA‐ECC. Comparisons are made between experimental results in the literature and those calculated by using the analytical model to show the accuracy of the model in predicting the load–deflection relationship, the moment–rotation relationship, and the moment–curvature relationship.

Numerical Modeling and Design Method for Reinforced Polyvinyl-Alcohol-Engineered Cementitious Composite Beams in Bending

“…The average values for ρ min , ρ t , and ρ y are 0.214%, 0.409%, and 1.846% for the HRB400-deformed steel bar, respectively. The actual reinforcement ratio in reference [21] was between the average balanced reinforcement ratio of 0.409% and the yield reinforcement ratio of 1.846%. Hence, the tensile reinforcement is in the post-yielded stage, while the compression strain at the edge of the compression zone reaches the peak compression strain when the beam is at the peak load.…”

“…In the table, f t is taken as 1.96 MPa according to fourpoint flexural tests; f t,cr represents the tensile cracking strength and is recommended to be 1.86 MPa; f t,cr is assumed to be 95% of the tensile strength f t [20]; ε t,cr represents the tensile strain when the stress is 0.95 times the peak strain; ε t,1 is the tensile cracking strain when obvious cracking forms; ε t,p is the tensile strain when a principal crack forms, namely, the localization strain. The steel constitutive model adopts the elastoplastic model and detailed data are shown in the literature [21].  represents the tensile strain when the stress is 0.95 times the peak strain;…”

“…, tp  is the tensile strain when a principal crack forms, namely, the localization strain. The steel constitutive model adopts the elastoplastic model and detailed data are shown in the literature [21]. The longitudinal reinforcement is embedded in PVA-ECC.…”

“…To predict the flexural properties of reinforced PVA-ECC beams, a nonlinear finite element model without initial flaws is proposed in this paper. Six four-point bending specimens from the literature [21] are simulated to evaluate the accuracy of the proposed model. Parameter analyses are conducted to investigate the effect of the reinforcement ratio, steel strength grade, and mechanical properties of PVA-ECC on the load-deflection behavior.…”

Damage Management of Concrete Structures with Engineered Cementitious Materials and Natural Fibers: A Review of Potential Uses

“…The crack bridging capability is limited with a low interfacial bond, allowing fibers to slip out easily, leading to low tensile ductility and large crack widths in ECC. Conversely, if the bond is too high, fibers tend to break instead of frictionally sliding out, reducing the composite's energy absorption and strain capacity [43]. Polymeric fibers generally have low bond strengths (<1 MPa), except for PVA fibers (frictional bond in the range 2-5 MPa).…”