Pullout performance of headed anchor studs in Engineered Cementitious Composites (ECC) with Polyvinyl Alcohol fibers

To study the pull-out resistance of headed anchor studs in Engineered Cementitious Composites (ECC) for steel-ECC composite structures, pull-out tests were carried out on 9 scenarios of ECC specimens. The failure modes, load-displacement curves, peak load (Nu), initial stiffness (K0.3), and ultimate displacement (Du) of studs in Polyvinyl Alcohol fiber (PVA)-ECC under different stud sizes (d = 13 mm and 16 mm), stud embedment depths (hef= 40 mm, 60 mm, and 80 mm) and fiber content (Vf = 2.0% and 2.5%) were obtained. Failure modes include (ductile) concrete cone failure, cone-splitting combined failure, and steel failure. For the specimens with concrete cone, either increasing d or hef increases K0.3, Nu, and Du, and Nu shows the greatest improvement. Increasing fiber content (Vf) exerts a significant enhancing effect on Nu, but exerts little effect on K0.3 and Du. Through the comparisons to the pull-out resistance of studs in high-strength concrete (HSC), the studs in ECC show evident advantages in ductility, toughness, and Nu. Based on the experimental results, the applicability of the original CCD model and two modified CCD models from literature to studs in ECC is discussed. The modified CCD model including the effect of stud size and specimen size presents the best accuracy in predicting Nu of studs in ECC. Overall, ECC is a promising material for steel-concrete composite structures, considering it evidently improves the pull-out performance of studs, thus the anchorage between steel and ECC.