体外预应力混凝土简支梁剪切性能试验研究

为了研究节段式体外预应力混凝土梁的剪切性能,采用剪跨比、配箍率、接缝类型、体内外预应力筋配比等参数进行了13根整体式和14根节段式(胶接缝和干接缝)体外预应力混凝土简支模型梁试验。描述了模型梁箍筋应力、体外预应力筋应力、挠度随荷载变化规律,以及破坏裂缝形成过程和破坏形态;分析了剪跨比、体内外预应力筋配比、接缝位置和数量及类型对梁剪切性能的影响。研究表明,节段式体外预应力混凝土梁的剪切性能和整体式梁有很大差异,接缝决定着剪切破坏形态与破坏裂缝的形成、较大削弱了梁的抗剪承载力、明显增大了破坏裂缝的宽度和梁体破坏时的变形;配置体内预应力筋能有效改善体外预应力混凝土梁的剪切性能;整体式体外预应力混凝土梁的剪切性能和一般预应力混凝土梁也有一些差异。

Experimental study on the shear behavior of simply-supported externally prestressed concrete beams

In order to study the shear behavior of segmental externally prestressed concrete beams,13 monolithic and 14 segmental(epoxy jointed and dry jointed) simply-supported externally prestressed concrete model beams were tested with the shear-span ratio,stirrup ratio,joint type,ratio of internal tendons to external tendons,etc.,as the parameters.Stress variations in the stirrup and the external tendons and deflection during loading are described,the failure crack generation and failure mode are also explained.The effects of shear-span ratio,ratio of internal tendons to external tendons,joint position,joint number and joint type on the shear behaviour of beams are analysed.The study indicates that there is significant difference in shear behaviour between segmental externally prestressed concrete beams and monolithic beams.The joint,a key factor affecting the failure crack generation and shear failure mode,causes great decrease in the shear bearing capacity,increase in the crack width and deflection of beams at failure.Internal tendons can effectively improve the shear behaviour of externally prestressed concrete beams.The shear behaviour of monolithic externally prestressed concrete beams also differ,in some aspects,from traditional prestressed concrete beams.