The Load-Transferring Model Study And Three Dimension Element Analysis For Steel Fiber Reinforced Concrete Thick Pile Caps

The calculation of inner force of pile caps establish on the bending theories of beam and plane, the checking computation of load bearing capacity for pile caps generally used calculation method of beam and plane. This kind of design method has only considered the stress in a special section of pile caps, but has no a consideration of complete stress flow inside the pile caps. When domestic and international scholar study pile caps deeply, people find that the plane section hypothesis of average strain is not fit in with pile caps, especially with thick pile caps, hence bring up many kind of load-transferring model of pile caps, such as tie-arch model, spatial truss model and limosis model.On the comparatively analysis of various design method to pile caps at home and abroad, studied the nonlinear finite element mechanics model of steel fiber reinforced concrete, applying finite element analysis software, made further research on load-transferring model of steel fiber reinforced concrete pile caps, found that the load-transferring mechanism of steel fiber reinforced concrete pile caps accords with spatial truss model, which made of tension-link and slanting-compression-link, on the base of these, put up slanting-compression-link's load bearing capacity simplified calculation formulas and given design step for steel fiber reinforced concrete thick pile caps, all of these were used background information for Specification for Technology of Fiber Concrete Structures, and given design and calculation reference for engineers as well.Besides, the mechanics performance of steel fiber reinforced concrete five-piles cap has been studied in this paper. In practical engineering applying, due to the geological condition or place's limit, sometimes a pile should be set under the column of pile caps, but this setting has not been described clearly in correlative code. When engineers design this kind of pile caps, because of lacking reliable theories, they have to rely on their experience. On the base of experimental research, using analysis of finite element, the mechanics character and reaction to pile caps of the middle pile of steel fiber reinforce concrete five-piles cap. The conclusion is that (1) For the thinner five-pile cap, with the same dimension of corner and middle pile, middle pile takes on more load. (2) With the increasing of pile caps' height, the difference of load bearing about middle and corner pile is reducing; when pile caps' height increases to some extend, there is nearly no difference between them. (3) With the adding of middle pile's diameter, the difference of stress is reducing. At last seeking after the application of steel fiber reinforced concrete five-pile cap in practical.Although the study is about steel fiber reinforced concrete pile caps, the result in this paper can fit up to reinforced concrete five-pile caps as well and has important reference value in engineering design.