No abstract

Lightweight (LW) concrete is finding increasing use primarily to decrease the dead load, reinforcements needed and member sizes. The beneficial effect of flexural fiber reinforced polymer (FRP) laminates in enhancing the capacity of normal-weight concrete has been well-demonstrated. However, such application on LW has not been explored in depth, especially with confining anchorage systems that can prevent premature debonding of the flexural laminates. This study investigated the effect of utilizing mechanical anchorage and FRP U-wrap anchorage on the performance of LW concrete beams. The carbon FRP laminate enhanced the flexural capacity of all strengthened beams by up to 12%. The CFRP U-wrap was found to be more effective than the mechanical anchorage in delaying the debonding failure of the flexural laminate and increasing its tensile strain by as much as 81%. However, the mechanical anchorage was more effective in increasing the elastic stiffness of the beams. Strengthened beams are likely to have increased durability due to the decreased crack width, length and spacing. The demonstrated failure modes of cover delamination and U-wrap debonding contradicted the theoretical failure mode from the American Concrete Institute (ACI) guidelines. Such guidelines do not currently include the contribution of FRP anchorage systems for concrete structures.