A screw adapted to be driven into a pre-drilled hole having a hole diameter in a concrete structure, with the screw comprising: a head; a shank extending from the head and defining a longitudinal axis, with the shank including a front segment and a rear segment spaced from the front segment along the longitudinal axis and located between the front segment and the head, with the shank having a shank diameter less than the hole diameter of the hole, with the front segment including a front end having a flat end face; and a thread spirally formed on the shank and extending to the rear segment from the front segment toward the head, with the thread including a plurality of thread convolutions and having a major diameter greater than the hole diameter; wherein at least three oblique ribs are formed on an outer periphery of the shank and located between any two adjacent thread convolutions of the thread at the rear segment and also at the front segment of the shank, wherein the at least three oblique ribs are spaced around the shank 34 circumferentially such that the front segment and the rear section of the shank respectively have at least three oblique ribs at cross-section, wherein each oblique rib has a trapezoid cross section with two lateral sides and a planar top face interconnecting the two lateral sides, with the planar top faces of the at least three oblique ribs defining a rib top diameter less than the major diameter of the thread convolutions and slightly less than or equal to the hole diameter, wherein the at least oblique ribs can crush and disperse concrete debris which comes out of a hole wall of the pre-drilled hole cut by the thread when the screw is driven into the pre-drilled hole. a head; a shank extending from the head and defining a longitudinal axis, with the shank including a front segment and a rear segment spaced from the front segment along the longitudinal axis and located between the front segment and the head, with the shank having a shank diameter less than the hole diameter of the hole, with the front segment including a front end having a flat end face; and a thread spirally formed on the shank and extending to the rear segment from the front segment toward the head, with the thread including a plurality of thread convolutions and having a major diameter greater than the hole diameter; wherein at least three oblique ribs are formed on an outer periphery of the shank and located between any two adjacent thread convolutions of the thread at the rear segment and also at the front segment of the shank, wherein the at least three oblique ribs are spaced around the shank 34 circumferentially such that the front segment and the rear section of the shank respectively have at least three oblique ribs at cross-section, wherein each oblique rib has a trapezoid cross section with two lateral sides and a planar top face interconnecting the two lateral sides, with the planar top faces of the at least three oblique ribs defining a rib top diameter less than the major diameter of the thread convolutions and slightly less than or equal to the hole diameter, wherein the at least oblique ribs can crush and disperse concrete debris which comes out of a hole wall of the pre-drilled hole cut by the thread when the screw is driven into the pre-drilled hole.