BENDING RESISTING MECHANISM OF EMBEDDED PILE BLOCK OF PILE CAP

Abstract

 On behavior of the pile-cap embedding prefabricate pile, many experiments and investigations of failure mode were conducted. However, the design-method of the pile-cap embedding the prefabricate pile and the method of evaluating the maximum bending strength are less well understood. This paper reports that the bending resisting mechanism of the pile-cap in cases where a single prefabricate pile is embedded by a single pile-cap.

 Bending resisting mechanisms are two type, lever mechanism of embedded pile and anchor mechanism on head face of pile. Lever mechanism resists the bending moment on the side surface of the prefabricate pile. M_teu0 (the ultimate bending moment from lever mechanism) is derived from the bearing strength of the concrete or the tensile strength of the horizontal re-bar to resist lever mechanism. Anchor mechanism is based on the anchoring re-bar on the head face of the pile and the axial force. M_Hu0 (the ultimate bending moment from anchor mechanism) is given by the bearing strength of the concrete.

 As the results of previous experiments which are SC-pile bending-shear tests with no axial force, no anchoring re-bar and changing ℓ (the embedded length) and the SC-pile bending-shear test with ℓ = 0mm, the authors have determined that the coefficient ß_te related to lever mechanism is 1.5 and the coefficient ß_H related to anchor mechanism is 1.8.

 M_u0 (the ultimate bending moment of under surface of pile-cap) is calculated by the accumulative strength of M_Hu0 and M_teu0. To confirm those resisting mechanism, we conducted bending-shear tests with SC-pile having thick steel pipe (steel pipe 400φ×19), changing axial force, shear-span ratio, embedded length and re-bar arrangement. As results, we ascertain that the M_u0 accumulative of M_Hu0 and M_teu0 can evaluate the maximum bending moment of the experimental result safely.