Study On Stress Behavior Of Unbonded Partially Prestressed Concrete Beams With HRB500Bars

Unbonded partially prestressed concrete structure is the important branch of post-tensionedprestressed concrete structure, has the remarkable advantages of construction is simple, easymaintenance, and the economic benefit, which has been widely applied in the civil engineering.At present, the test research of unbonded partially prestressed concrete beam with HRB500steelbars in different the layout of unbounded tendons is still belong to blank, the restrictions on theforce performance full understanding.The paper produced nine tested beams, which are divided into three groups, two of whichwere the prestressed steel line cloth bar form, another group using parabolic cloth bar form,analyses the impact of non prestressed reinforcement ratio and the strength grade and prestressedreinforcement fabric reinforced form on the test beam stiffness and deformation, prestressedreinforcement limit stress increment, the normal section crack resistance property, the ultimateflexural capacity, and according to the test data check the current specification given theapplicability of the formula.The results show that: HRB500reinforced has no significant effect on cracking load andstiffness, but it can significantly improve not only the increment of ultimate bearing capacity butalso the normal section’s bending resistance; with HRB500grade steel reinforcement ratioincreased after cracking stiffness improved, UPC beams in line cloth according to regulations(JGJ92-2004) given calculation formula for calculation of the rigidity value be conservative,stiffness calculation value can be appropriately increase, it is suggested that stiffness coefficientof correction take1.2; Prestressed reinforcement limit stress speaking, so as long as theprestressed tendon stress increment ultimate analysis method is reasonable, the unbondedpartially prestressed concrete beam of normal section flexural bearing capacity error will notgreat; Given the current specification is suitable for the loss of prestress, mid-span deflection,crack bending moment and bending bearing capacity calculation formula.