Mechanical anchorage for shear rehabilitation of reinforced concrete structures with FRP: An appropriate design approach

The focus of this dissertation was to not only show that mechanical anchorage was required for shear strengthening, but also to develop an appropriate design methodology for the anchorage system. The study provided both the global and local load path requirements of an anchored externally bonded FRP shear stirrup. A novel fiber anchor system was developed to promote attachment of the FRP after debonding, and limit the strain relaxation found with the use of other anchor systems.; Component level tests on single anchored and unanchored FRP stirrups were conducted through the Small Crack Shear Pull-off Experimental Program. This study primarily compared the forces across a crack throughout the complete load history of a stirrup due to crack bridging. The study was used to investigate the efficacy of various mechanical anchorage configurations.; Structural level tests were completed on half scale cantilever beams using both anchored and unanchored FRP stirrups. These tests showed that multiple unanchored FRP stirrup contributions could not be relied on throughout the full development of flexural failure. Additionally it showed that proper detailing of the fiber anchorage system could provide a conservative design estimate without increasing the amount of external strengthening.; A Discrete Grounded Spring Model was used to predict the debonding limit of a single FRP stirrup. A Strain Drop/Crack Jump Model was used to show how an unanchored and anchored stirrup responds after debonding. A Frictional Sliding Model was used to develop the local demands placed on the fiber anchorage system, and insure that the uncoupled limit states of the concrete, steel, and FRP could be attained in each element across the critical shear crack. A Fiber Pull-out Model was used to predict the actual local fiber anchorage capacity. Lastly, an Arching model was used to describe the global concrete demands required of the anchored FRP stirrup. All of these models were used in the development of appropriate design recommendations for FRP shear stirrups.