This thesis investigates the shear capacity of concrete T-beams prestressed with CFRP cables (CFCC) and contributes to the scarce research available for shear behavior of FRP prestressed concrete beams. Four beams are tested under distributed load, while twelve beams are tested under four point bending. Three different a/d ratios of 1.5, 2.5 and 3.5 are investigated. The results show that the shear capacity of the beams increases significantly when a/d is reduced below 2.5. The effect of FRP stirrups on the shear capacity of the beams is investigated and it is shown that the minimum required stirrups according to CSA-S6-10 are ineffective in deep beams with a/d = 1.5. The accuracy of current North American shear design formulas for FRP prestressed concrete beams subjected to four-point bending and distributed load is evaluated. The available strut and tie models are studied for determining the shear capacity of FRP prestressed deep beams.

This thesis investigates the shear capacity of concrete T-beams prestressed with CFRP cables (CFCC) and contributes to the scarce research available for shear behavior of FRP prestressed concrete beams. Four beams are tested under distributed load, while twelve beams are tested under four point bending. Three different a/d ratios of 1.5, 2.5 and 3.5 are investigated. The results show that the shear capacity of the beams increases significantly when a/d is reduced below 2.5. The effect of FRP stirrups on the shear capacity of the beams is investigated and it is shown that the minimum required stirrups according to CSA-S6-10 are ineffective in deep beams with a/d = 1.5. The accuracy of current North American shear design formulas for FRP prestressed concrete beams subjected to four-point bending and distributed load is evaluated. The available strut and tie models are studied for determining the shear capacity of FRP prestressed deep beams.

The actual shear capacity of existing concrete structures is often unable to meet current standard requirements. This may be attributable to increased load requirements, inadequate shear provisions in the original design or increased demand in shear capacity owing to flexural strengthening. However, available methods of assessment are often conservative, and the actual strength may be sufficient to sustain the specified assessment load. Therefore, it is important that realistic assessment methods are employed. This research comprises an investigation into the shear capacity of prestressed concrete bridges and into the feasibility of a novel strengthening approach, both through comprehensive laboratory experimentation and theoretical analyses. The laboratory testing indicates that the shear capacity of prestressed concrete bridges, post-tensioned transversely to form a deck, can be significantly greater than suggested by the relevant standards. The strengthening method proposed, namely deep embedment of steel or fibre-reinforced polymer (FRP) bars, is found to be feasible and very effective for reinforced concrete (RC) and prestressed concrete (PSC) beams of any size. Analytical models based on the upper-bound theorem of plasticity theory are successfully developed and applied, resulting in much more realistic predictions than those from current standards and codes when assessing shear capacity. For the strengthened beams, in addition to an upper-bound model, a strengthening design method based on a truss analogy is developed, which can be directly implemented into codes of practice. The analytical methods permit the assessment of existing longitudinally and laterally prestressed concrete bridges for shear capacity in a rational manner, and then to determine the capacity of a practical shear strengthening system if the bridge turns out to actually be understrength. Use of the proposed methodology will allow significant savings, as the costs associated with replacing or strengthening the structure can be avoided or minimised, encouraging a sustainable approach.