Prestressed Carbon Fibre Reinforced Polymer (CFRP) system is generally used for strengthening
reinforced concrete beams where CFRP laminate can improve both the strength and serviceability behaviour of
reinforced concrete beams via increasing the overall member stiffness. However, the applicability of this technique
to strengthening steel structures is still lagging behind its application to concrete structures. In this study,
the flexural behaviour of steel I-beams strengthened with prestressed CFRP laminate using a mechanical anchorage
system is experimentally investigated. A total of nine steel beams subjected to flexural loading are
tested in various conditions to evaluate the effectiveness of the proposed strengthening system. The experimental
investigation confirmed that CFRP prestressing increases the ultimate load of the strengthened steel
beams and moderately delays the premature debonding failure of the CFRP laminate. Even with low level of
CFRP prestressing, significant enhancement in the ultimate load of the strengthened beam was recorded. Beams
strengthened using non-prestressed CFRP laminate mainly failed due to premature debonding of the laminate
with a slight increase in the failure load. Mechanical end anchorages maintain the CFRP laminate prestress after
releasing the jacking force without encountering any debonding of the CFRP laminate till final failure of the
strengthened steel beam. The results of the experimental programme and its outcomes are presented and discussed.