Pre-tensioned centrifugal concrete structure with steel strands

A pre-tensioned centrifugal concrete pillar, comprising

• a hollow concrete body with two ends;
• a steel cage having an axis and disposed inside the concrete body, the steel cage comprises a plurality of pre-stressed rebars disposed parallel to the axis of the steel cage, a plurality of stirrups placed around the plurality of rebars;
• and
• a first plate and a second plate covering the two ends of the body, each of the first plate and the second plate has an inside facing the body and an outside facing away from the body, each plate defining a center opening;
• wherein, the pre-stressed rebars are steel strands, and an end of each steel strand is connected to the first plate through a clip connecting mechanism;
• the clip connecting mechanism comprises:
• a plurality of counter recesses provided on the first plate;
• a transition element matched with the counter recesses in dimension is disposed inside each counter recess, the transition element has an annular stop shoulder resting on the counter recess and a conical transition through hole, the conical transition through hole has a diameter increasing from the inside toward the outside of the plate and a position of each conical transition through hole corresponds to each steel strand;
• and
• multiple clips disposed inside each transition through hole, each clip is composed by three conical parts with a toothed inner surface;
• the multiple clips are spliced together to form a chuck assembly for clamping each steel strand, and a peripheral surface of the chuck assembly has a conical surface matching with corresponding conical transition through hole;
• a clamping hole is formed in the center of the chuck assembly with the toothed inner surface for receiving and clamping a steel strand, the steel strand passes through a corresponding clamping hole and is clamped tightly;
• an outer surface of the chuck assembly is flush with or is lower than an outer surface of the first plate.