Effect of Tendon‐Area Loss on Flexural Behavior of P/C Beams

Abstract

Prestressing tendons can be affected by corrosion or mechanical damage. The paper deals with prestressed structural systems consisting of a prestressed precast concrete beam and a cast‐in‐place slab. Noncomposite and composite beams with bonded tendons are considered. Procedures are developed for the analysis of uncracked and cracked sections. The moment‐curvature relationship is obtained using the developed algorithms and formulas. The formulas are derived for the curvature corresponding to cracking stress, decompression, and ultimate moment. Three algorithms are formulated for iterative procedures. The objective of algorithm one is to determine the moment and rotation axis location corresponding to a given curvature. Algorithm two can be used to determine the curvature and rotation axis location for a given moment. The third algorithm is used to determine the axial strain when the beam is subjected to dead‐load moment. The analysis is based on stress‐strain curves for materials (steel and concrete) and other parameters. For linear elastic materials a closed‐form solution is derived. Even though the moment‐curvature relationship for a typical prestressed concrete beam is nonlinear, its lower part, within the design load range, is very close to linear. The procedures are demonstrated on a typical prestressed concrete bridge girder. Moment‐curvature relationships are obtained for various degrees of tendon‐area loss.