Deflection calculation of partially prestressed concrete beams under heavy duty

Abstract

To predict bridge deformation laws under existing traffic loads
and identifies the main influencing factors of midspan deflection
of the structure, this study performed static and fatigue tests on
seven pieces of prestressed concrete scale model beams using the
pre-tensioning method. The general variation laws and characteristics of deflection were studied, and the calculation method
of deflection of partially prestressed concrete beams under heavy loads was discussed. Results demonstrate that the changes of
concrete strain along the section height conform to the plane hypothesis. The deflection of prestressed concrete beams under heavy load basically conforms to the “quick-stable-quick” variation
law, and the change rate is significantly higher than that under
normal operating loads. The deflection after the fatigue cracking
of prestressed concrete beams under heavy load can be calculated from the residual and load deflections. Based on the established formula of fitting deflection, the amplification coefficient
of deflection during the fatigue steady state is approximately
20%–35%, and the amplification coefficient at critical failure is
approximately 80%–100%. This study provides references for the
fatigue performance assessment of prestressed concrete beams
under heavy traffic loads and the selection of reinforcement time.