Experimental Study On Mechanical Behavior Of Prestressed Concrete Tensioning At Early Age Beams Under New Tensioning Technology

Because the characteristics of the material,prestressed concrete structure needs curing time and conditions in order to satisfy the requirements of structural strength.But during the practical engineering,for more economic interests,construction units always over emphasis on shortening the duration of a project.In order to accelerate the speed of construction,a lot of prestressed concrete structures will be mixing,vibrating and releasing at early age after pouring.But at that time the concrete under loadings is still in the curing stage,whose every performance index has not meet the qualification completely.So bearing construction load at early age will cause safety or quality accidents more possible.Nowadays prestressed concrete structure is widely used in large-span structure as bridge engineering to control the cracking,stiffness and deformation,while related theories and experimentals are also being studied.Experts and scholars from home and abroad have a rather deeply study of prestressed concrete structure at serviceability limit stage,but its much less about prestressed tension technology at early age.But the study of prestressed concrete structure tensioning at early age has great significance on reducing prestress loss during long-term use and improving the service life of structure.The experiment about prestressed concrete structure tensioning at early age is relatively less.It has not fully realize and study about the bearing capacity,stiffness,deformation and deflection of concrete structure tensioning at early age.This paper presents a new prestressed tension technology and introduces it.Then using it to installment tensioning three prestressed concrete beams at early age,then doing experimental study on bending behavior under cyclic loadings in order to study the influence and improvement of the bearing capacity,stiffness,deformation and deflection about this new tension technology.This paper also use Abaqus to model building and simulate the behavior of prestressed concrete beams under vertical static loading in order to recognize more about the influence of early-age and installment tensioning.The result shows that when at the earlier tension age,the cracking load and yield load are higher,the carrying capacity and stiffness are stronger under the same load.The tension age does not have an obvious improvement on the carrying capacity and deflection after the yielding.The Abaqus finite element model can simulate the experimental results accurately and it is simple operation,which has high application value.