Abstract:
This thesis describes a theoretical and experimental
investigation into the nature of the bursting stresses in
the anchorage zone of a post-tensioned prestressed beam.
Experimental measurements of the strains in the
reinforcement were made after the concrete had cracked.
These strains were measured by means of electrical
resistance strain gauges. A total of twenty one beams
were tested.
A linear elastic finite element program SAP IV was used
for the analytical study. The two dimensional bursting
stresses in the uncracked anchorage zone were determined
and the values were found to be in close agreement with
those given by Guyon. The behaviour of a cracked
anchorage zone with reinforcement was also studied. The
reinforcements were represented by a series of linear
elastic springs. This finite element model gives
computed values of stirrup forces and crack widths which
compare favourably with the experimental data.
The study shows that the bursting force in a cracked
anchorage zone depends on the transverse stiffness of the
section. The computed stirrup forces calculated from
an assumed elastic uncracked section (Guyon's solution)
overestimate the forces in the reinforcement.
