Strengthening full-scale damaged prestressed concrete bridge girders with CFRP sheets

A large percentage of bridges in Canada were constructed over thirty years ago and their condition steadily declining. A product of deterioration and corrosive environments, many structures have been rendered unfit as per design codes and [are] structurally unsound. Constructing new structures and conventional repair methods are financially costly. A solution lies in fibre reinforced polymers (FRP). This thesis summarizes experimental projects regarding FRP usage in field applications. An actual damaged bridge girder was removed and rehabilitated with the FRP system. It was loaded incrementally and statically, nearing failure, investigating the reliability of the rehabilitation technique proposed to revive strength capacity to an acceptable level. A finite element computer simulation was created, modeling the load-history of the rehabilitated girder, as well as three full-scale damaged duble-tee girders, recently rehabilitated and loaded to collapse. This full-scale testing program and computer replication shall provide engineers with confidence in using FRP technology in girder strengthening.

Strengthening full-scale damaged prestressed concrete bridge girders with CFRP sheets

A large percentage of bridges in Canada were constructed over thirty years ago and their condition steadily declining. A product of deterioration and corrosive environments, many structures have been rendered unfit as per design codes and [are] structurally unsound. Constructing new structures and conventional repair methods are financially costly. A solution lies in fibre reinforced polymers (FRP). This thesis summarizes experimental projects regarding FRP usage in field applications. An actual damaged bridge girder was removed and rehabilitated with the FRP system. It was loaded incrementally and statically, nearing failure, investigating the reliability of the rehabilitation technique proposed to revive strength capacity to an acceptable level. A finite element computer simulation was created, modeling the load-history of the rehabilitated girder, as well as three full-scale damaged duble-tee girders, recently rehabilitated and loaded to collapse. This full-scale testing program and computer replication shall provide engineers with confidence in using FRP technology in girder strengthening.

Flexural Behavior of Unbonded Prestressed Concrete Bridge Girders

This paper presents an experimental and numerical investigation on the flexural behavior of unbonded prestressed concrete (PC) T bridge girders. Three unbonded PC T bridge girders with different prestress degrees spanning 3 m were selected to perform four-point bending tests and then determine the flexural performance. Flexural capacity, crack development and failure mode, load-deflection curves, strain in longitudinal rebars, and stress in prestressing strands of unbonded PC T bridge girders are experimentally analyzed. Subsequently, three-dimensional finite element (FE) models are built and validated by experiments to investigate the effect of different design parameters on flexural behavior of bridge girders. Results generated from experiment and numerical studies show that the flexural destruction behavior in unbonded PC T bridge girders experiences elastic, elastic-plastic, and ductility stages, similar to that of PC T bridge girders. The prestress degree and load location have significant influence on the destruction process in unbonded PC T bridge girders. A lower effective prestress degree can reduce the distribution range in cracks and also increase the width of cracks. Stress in prestressing strands under anchor increases rapidly after concrete presents obvious cracks, and the fracture area within prestressing strands increases with the elevation of prestress degree. The aim of this study is to provide a reference for the design and practical application of unbonded PC T bridge girders.