A new approach to testing anchorage mechanisms: Applications and limitations

The use of externally bonded Fiber Reinforced Polymer (FRP) laminates for flexural strengthening has become increasingly popular in recent years. Yet, under critical loads strengthened members suffer from premature failure via debonding of the composite laminate from the concrete substrate. Research studies have shown that if sufficient anchorage can be provided to concrete then debonding can be slowed or eliminated completely. To this point plate-end anchorage mechanisms have been tested using full scale beam or slab specimens. Although this method is effective it is time consuming and expensive. This paper presents a conceptual outline of a new approach for testing plate-end anchorage mechanisms for strengthened beams and slabs in flexure with externally bonded FRP laminates. Small-scale concrete prism specimens are used to test anchorage. The behavior at the plate-end region is modeled using a single lap pull test. Laboratory testing of two anchorage designs using the proposed method was completed to validate the approach. Two finite element models are also presented to compare the stress states in specimens used for experimental work and modified test specimens that incorporates tension in concrete due to beam bending. Results from experimental tests, FEM, and applications and limitations of the proposed method will be presented.