Study On Failure And Evolution Law Of Longitudinal Reinforcing Bar Connection Interface Of Prefabricated Concrete Structure

Due to its low labor cost,short construction period,small noise and dust pollution,prefabricated concrete structure is used in practical engineering increasingly.For prefabricated concrete structures,the connection of steel bars is crucial.Therefore,this article carried out the study of prefabricated concrete structure longitudinal grouting anchor reinforcement connection.The damage evolution law of research using digital speckle correlation method(DSCIM).The test of longitudinal steel grouting anchor connection of prefabricated concrete structure is carried out.The destruction process of reinforced grouting anchor connection were observed,and analyze the damage evolution law,obtain the damage evolution of reinforced grouting anchor connection interface regularity and deformation field evolution characteristics.Based on the bond slip theory of reinforced concrete,the calculation model of bond slip between reinforcement and grouting material is established.The main conclusions are as follows:(1)In order to obtain the failure evolution law of the interface between the reinforcement and grouted anchor,based on digital speckle correlation method the drawing test method of reinforced concrete anchor is designed.A semi-cylindrical specimen was used in this experiment.It is convenient to observe the failure evolution process of the interface between reinforcement and grouting material.(2)The evolution rules of deformation field and strain field of the failure process were obtained through the test with the digital speckle correlation method(DSCM).In experiment process,drawing force is mainly transmitted through the bond between the reinforcement and the grouting material from the loading end to the free end.Along the longitudinal direction of the reinforcement,the bond stress decreases with the increase of the bonding depth.Its influence is mainly concentrated in the range of the bonding length of the first 2/3 specimens.In the direction of the vertical reinforcement,from the center of the specimen to the outside,the influence of drawing force on the grouting material and concrete is decreasing.(3)The thickness of grouting material has a certain influence on the failure evolution law.With the increase of the grouting material thickness,the influence range of the reinforcement drawing force on the grouting material deformation field is increasing.At the same time,when the grouting material thickness exceeds the limit value,the range of the grouting material deformation field affected by the drawing force will not expand.(4)By analyzing the bonding-slip curve of the interface between reinforcement and grouting material,the calculation model of bonding-slip between reinforcement and grouting material was established.The results show that the model is reliable and easy to use.