Development, Optimization and Testing of an Innovative Wedge Anchorage for CFRP Plates

Abstract

Replacing degraded concrete structures can be quite expensive and time consuming; thus, strengthening these structures with fiber reinforced polymer (FRP) elements, such as carbon FRP (CFRP) plates, is more practical. Prestressing FRP elements is one of the most economical used solution due to its effect on utilizing the high strength of the FRP materials while improving the performance of structural elements. In order to prestress the FRP component, gripping using anchorages must be provided at both ends. However, anchoring FRP plate is challenging due to its vulnerability to lateral loading; therefore, specially designed anchorage systems are required to grip FRP plates effectively to avoid any premature failure.

The presented work investigates the development and optimization of an innovative anchorage that is reliable, reusable, compact and light in weight for gripping CFRP plates. To fulfil these requirements, a wedge anchorage system is chosen as the most suitable for gripping CFRP plates Material selection process is conducted to select the optimal materials for the sleeves, the wedges and the barrel of the anchorage.

An FEM model of the wedge anchorage is developed using ABAQUS finite element package. An optimization process is performed to find the optimal dimensions of the anchorage through which the anchoring strength and the reusability of the anchorage are improved. The effect of the presetting distance on the performance of the optimized anchorage is investigated. Several failure theories are used to investigate the likelihood of CFRP premature failure. Two new analytical models are developed to verify the accuracy of the FEM model. The results of the analytical models are compared well to the FEM results.

The optimized wedge anchorage is then manufactured and experimentally tested. Eight tensile tests are performed to evaluate the performance of the optimized anchorage by gripping the sides of the CFRP plates using the optimized anchorage and a larger dead-end anchorage. Five tests are performed by presetting the optimized anchorage using presetting rig, two of which use hard copper sleeves. The other three tests are conducted by hammering the optimized anchorage. The dead-end is presetted in every test to avoid CFRP slipping. The optimized anchorage system is capable to carry the guaranteed ultimate tensile strength of the CFRP plate when soft sleeves are used. The effect of presetting distance on the CFRP slipping is investigated. Damage analysis is performed after conducting eight tensile tests to examine the reusability of the optimized wedge anchorage.