Theoretical Analysis And Experimental Study On Mechanics Performance Of Pretensioned Prestressed T-shaped Concrete Beam With Bent Tendon

In recent years,with the continuous improvement of the design requirements of large span structure,the prestressed concrete beam with bent tendon is gradually paid more and more attention by the researchers.It has already been applied in the cross sea bridge,highway and high speed railway.The bent tendon reinforcement method is a kind of pretensioned method.The technique of pretensioned prestressed concrete beam with bent tendon overcomes the shortcoming that prestressed beam with traditional pretensioned tendons can not be applied to large span.And it can change the shape of the prestressing tendon.So it can be applied to the construction of large span concrete bridge.But the existing structures are made of double bent tendons which has two bending points of the prestressing tendon.However,the mechanical properties of prestressed concrete beam with single bent tendon are not studied.Single bent tendon refers to the prestressed tendons in the middle of a bend.Compared with double bent tendon,it reduces the prestress loss caused by the friction between the prestressing tendon and the bender.At the same time,the construction cost is reduced.So it has a broad application prospectIn the background of the construction of a bridge in Sui-Guang Expressway,the 30m single fold-line pretensioned prestressed concrete beam was adopted as the research object.The theoretical analysis and model test study on the mechanical properties of 30m single fold-line pretensioned prestressed concrete beam is researched.And it provides the research basis for the engineering application and popularization of the single fold-line pretensioned prestressed concrete beam structure.The research work of this thesis is shown as following:(1)The load balancing method of fold-line prestressed concrete members are introduced.According to the 30m single fold-line pretensioned prestressed concrete T beam reinforcement and section form,the prestressing force of prestressed tendons are calculated.The prestress and bending moment are calculated by the equivalent load method.The bending and shear bearing capacity is calculated and analyzed.Finally,the relevant calculation suggestions are put forward(2)The test loading scheme is also designed,including the measuring point arrangement,the loading scheme,the loading system and the loading device,in order to further carry out the model test research necessary preparation.(3)A full scale model of 30m single fold-line pretensioned prestressed concrete T-beam was subjected to a static loading test.The performance of T-beam is evaluated synthetically from the aspects of failure mode,failure mechanism,carrying capacity,stiffness and crack resistance.The results show that the indicators of the beam meet the specification requirements.By comparing the experimental results with the theoretical results,the results are in good agreement.The analysis of the effective stress distribution width of top coagulation is carried out and the suggestions for effective width reduction are proposed.