PROPOSED METHODOLOGY FOR COMPUTING OF UNBONDED TENDON STRESS AT FLEXURAL FAILURE

This study is the first part of a theoretical and experimental research series on the unbonded tendon stress in prestressed concrete members. The paper describes a computational method of the unbonded tendon stress at the flexural failure of a member. First, the previous design equations were examined to find their advantages and disadvantages. Then, a new design equation was proposed with the consideration of the global compatibility requirement and the plastic hinge length. The proposed design equation was derived so that main parameters and their combination were obtained from theoretical study, and then the coefficients were determined by regression using previous test data. The previous experimental results wee used to examine American Concrete Institute and American Association of State Highway and Transportation Officials Load and Resistance Factor Design (LRFD) code equations as well as the proposed equation. The proposed equation showed good agreement with previous test data.