Mechanical Behavior Of The Steel Fiber Reinforced High Strength Concrete Four-pile Cap

Nowadays, with rapid development of high-rise building, water conservancy project, roads and bridges, the performance of the foundation has become more and more important. Pile foundation, which can reduce the uneven settlement of foundation and has excellent seismic performance, has been applied widely in practical project. As a connecting link, the cap of pile supports on the piles under column and it is such an important specimen of foundation that the research on the mechanical properties of pile cap becomes very meaningful.Steel fiber was applied in reinforced high strength concrete pile caps in the paper. Through the experiment of 9 specimens of steel fiber reinforced high strength concrete (SFHSC) four-pile caps in 1/5 ratio, the failure model of SFHSC four-pile cap was studied and the mechanical bearing of SFHSC four-pile cap was analyzed based on the curves of strain in reinforcing bar and the curves of concrete strain. The main contents are as follows.(1) Based on the description of experimental course and phenomena, the failure model of SFHSC four-pile cap belongs to flexural failure. Incorporation of steel fiber in high strength concrete has improved the ductility and deformation capacity of four-pile cap.(2) The mechanical behavior and the important factors on the cracking load and ultimate bearing capacity of the SFHSC four-pile cap were studied. It indicates that with the increases of the volume fraction of steel fiber, the effective thickness and reinforcement ratio of pile cap, the bearing capacity and anti-crack performance of four-pile caps improves largely.(3) Basing on the flexure theory and experimental data, the formula of ultimate bearing capacity of SFHSC four-pile cap was obtained. The agreement of calculation with experimental data is good.