Static and fatigue behaviour of prestressed concrete beams strengthened with prestressed CFRP sheets

To the knowledge of the author, the fatigue behaviour of prestressed concrete (PC) beams strengthened with prestressed carbon fibre reinforced polymer (CFRP) sheets has not been adequately addressed. To address this deficiency, the fatigue behaviour of a PC beam externally strengthened with prestressed CFRP sheets has been investigated with a certain prestress level in the CFRP sheets. The research work of this thesis also examined the efficiency of a CFRP sheet strengthening system for strengthening understrength beams to a designed strength level and the performance of the system in fatigue loading.; Four large-scale prestressed concrete beams (3.6m) were tested. Two of them were unstrengthened control beams and the other two were strengthened with prestressed CFRP sheets. One of the control beams had two steel strands and was regarded as the standard beam that did not need to be strengthened; the other had only one steel strand and served as the understrength beam that needed to be strengthened to a strength level comparable to the two-strand standard beam. Both of the strengthened beams had only one steel strand. One of the strengthened beams was tested in monotonic load; the other was tested in fatigue load. (Abstract shortened by UMI.)...