Experimental study on flexural and shearing properties of modified concrete pipe piles

The flexural and shearing properties of innovatively invented reinforced prestressed concrete pipe piles are studied through a comprehensive field test program. The allocations of nonprestressed rolling rebar evidently improve the flexural properties except the cracking resistance, and a larger reinforcement ratio of prestressed steel bar leads to a greater improvement. The new technology also reduces the length and average widths of cracks of concrete, whereas expands their distribution to some extent. The stresses of both type piles concentrate on pure bending section. The strain of mid-span cross section accords with the hypothesis of planar section until the concrete cracks and neutral axis moves higher correspondingly. The results of shearing tests show that the allocations of nonprestressed rolling rebar (or incensement of stirrup ratio at the same time) change the distribution of stress and cracks and decrease the deformation, whereas don't evidently improve the shearing capacity. The research shows the outstanding flexural and shearing properties of the new type pile.