新型混凝土管桩抗弯剪性能试验研究
Experimental study on flexural and shearing properties of modified concrete pipe piles
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摘要: 创新研发了钢筋加强型预应力混凝土管桩,并进行了抗弯及抗剪性能方面的对比试验研究。抗弯试验发现,非预应力螺纹钢筋的配置较大幅度改善了预应力混凝土管桩的抗弯性能,且预应力钢筋配筋率越低效果越为明显,但抗裂性能没有明显提高。螺纹钢筋的配置明显减小了桩身裂缝的长度和平均宽度,裂缝分布范围及数量有一定幅度的增加。两种类型管桩的主要应力均位于跨中纯弯段内,裂缝出现以前跨中界面应变基本符合平截面假定,裂缝出现后中性轴上移。抗剪试验显示,非预应力螺纹钢筋的配置(或箍筋同时加密)改变了桩身的应力和裂缝分布规律,较大幅度减小了管桩在剪力作用下的变形量,但没有明显提高管桩的抗剪承载力。此创新型管桩在抗弯及抗剪性能方面的优势是明显的。Abstract: The flexural and shearing properties of innovativelyinvented 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 barleads 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.