scope:

This guide provides recommendations for the selection and design of FRP systems limited to externally bonded FRP laminates and near-surface-mounted (NSM) FRP bars/strips for increasing or restoring the in-plane and out-of-plane strength of undamaged or damaged URM and RM walls and columns. Infill walls are not included in this guide.

The guide is applicable to masonry structures made of clay bricks, concrete masonry units, and natural stones using conventional types of mortar. The effectiveness of FRP systems is highly dependent on the adequate surface preparation of the masonry substrate. Masonry elements have different textures and uneven surfaces due to units and mortar joints that can affect the effectiveness of FRP systems if the masonry surface is not properly prepared.

For masonry with significant deterioration, questionable mortar bond, as well as cracking, element displacement, or both, traditional repair procedures may be required to be used in combination with FRP strengthening. Procedures and requirements for traditional methods for repair and strengthening of masonry are not covered in this guide. Assessment and Retrofit of Masonry Structures (Hamid and Schuller 2019) provides background and guidance for other methods for repair and strengthening.

Before starting the project, the licensed design professional should determine the design basis code (DBC) under which the evaluation, repair, and rehabilitation will be implemented. The DBC will establish the extent of the repairs and rehabilitation, evaluation methods, and design loads. The DBC is the code legally adopted by a jurisdiction, under which the assessments, repairs, and rehabilitations are designed and constructed. Depending on the jurisdiction and project conditions, the DBC can either be the International Existing Building Code (IEBC) or a local existing building code. This guideline does not cover code compliance requirements. Refer to ACI 562 for guidance on how to determine the DBC.