Non-linear analysis of prestressed concrete t-beams

Abstract

In the Netherlands many concrete bridges that were built in the sixties and seventies are still in service. One subset of these bridges consists of prestressed concrete T-beams with cast-in-between slabs, cross-beams and transverse prestressing. Upon (re)assessment, the strength of these bridges is often too low. However, for this type of bridge several mechanism, that could possibly contribute to a higher load bearing capacity, are usually not taken into account. One of these mechanism is compressive membrane action (CMA), in transverse direction, in the concrete deck slab. Another potential mechanism is arch action, in longitudinal direction, in the T-beam. To investigate these mechanism or the so called ‘system behaviour’, and the ultimate load capacity, a T-beam bridge from 1962 was tested in seven full size collapse tests. In four tests the deck was sawn in longitudinal direction so that it became possible to test the load capacity of the individual beams. The individual beam tests are analyzed using a 3D non-linear finite element model. In the experiments, the load was placed at two different positions from the support. It was found that the nonlinear analysis shows good agreement with the load placed at 2.25 m from the support. However, with the load at 4.00 m from the support, the non-linear analysis shows an overestimation of ∼15%. Ultimately, this research aims to improve the calculation methods for the existing T-beam bridges in the Netherlands.