Abstract: Ordinary ultra-high strength concrete pipe pile with prestressed steel bar is of low deformation ductility and horizontal load-bearing capacity. To tackle this problem, we replaced the prestressed bar with prestressed steel strand and compared the performances (including shearing capacity, deformation ductility, damage characteristics and cracking pattern) between prestressed steel strand ultra-high strength concrete pipe piles and ordinary prestressed ultra-high strength concrete pipe piles via shearing performance tests on six full-scale pipe pile specimens of three commonly-used pile types. Results evinced that replacing steel bars with steel strands as main reinforcement could effectively improve the deformation ductility and the ultimate load-carrying capacity of pipe piles under shearing condition. The cracks of ultra-high strength concrete pipe pile with prestressed steel strand develop more densely and uniformly, shorter in vertical direction yet with more lateral bifurcations than those of ordinary prestressed ultra-high strength concrete pipe piles. Ordinary prestressed ultra-high strength concrete pipe pile specimens are destructed following the tensile failure of steel bars; the failure of ultra-high strength concrete pipe pile specimens with prestressed steel strand are generated by the crushing failure of compressed concrete zone with shearing failure lagging behind flexural failure.

Key words: pipe pile, ultra-high strength concrete, prestressed steel strand, shearing performance, ductility, crack distribution