CALCULATION OF PUNCHING SHEAR BEARING CAPACITY OF PILE CAPS WITH BOTTOM REINFORCEMENT ARRANGEMENT CONCENTRATED AT EXTENT NEAR PILE TOP

At present，there is no formula which calculates the quantitative influence of the bottom reinforcement arrangement concentrated at the extent near the pile top on the punching bearing capacity of pile caps． Based on the spatial strut-and-tie theory of pile cap punching failure，a gradual least square method for multiple variables was used，and calculative formulae were derived for that sort of reinforcement of the pile cap． Verification with the published test data of changeable number and arrangement of pile in the literatures both at home and abroad， indicated that the proposed formulae were rational． It was expected that the engineering cost of pile caps and the slab of pile raft could be reduced by the rational arrangement of longitudinal reinforcement．