Abstract
Abstract
Research on six-pile caps mainly focused on reinforced concrete six-pile caps and steel fiber reinforced ordinary strength concrete six-pile caps. In order to study the force mechanism of steel fiber reinforced high strength concrete (SFRHSC) six-pile caps, eight SFRHSC six-pile caps with the plane dimensions of 960 mm × 600 mm were subjected to static load test. The experimental variables include the volume fraction of steel fiber (0 %, 0.5 %, 1.0 %, 1.5 %), concrete strength grade (C40, C60), effective thickness of pile caps (160 mm, 210 mm, 260 mm) and reinforcement layout (uniform grid, bunched). The tests were carried out to measure and analyze the crack development and failure mode, the load-deflection curve, the concrete strain and steel strain of specimens. On this basis, finite element analysis was conducted by ABAQUS and compared with the experiments. The results show that the failure mode of SFRHSC six-pile caps is the punching failure, and the load-transferring mechanism of six-pile caps conforms to strut-and-tie model. With the increase of the effective thickness of pile caps, the bearing capacity of specimens can significantly increase, and the fiber volume fraction of about 1 % has the best effect on enhancing the bearing capacity of SFRHSC pile caps. Finally, the calculation method for the punching shear capacity of SFRHSC six-pile caps based on strut-and-tie model was proposed.