A method and an article of manufacture are disclosed for reinforcing various structures with only partially accessible circumference, such as columns closely adjacent to or protruding out of a wall or beams holding a ceiling. Some of these structures may be partly or completely submerged in water, such as retaining walls on the sides of rivers and water-ways. In some embodiments a prefabricated shell will fully or partly cover the exposed and reachable part of the structure and will be secured in place by various means. The shell may hug the structure tightly or loosely and the space between the shell and the structure may be filled with such curable materials as glue, epoxy, grout, concrete and the like. In various embodiments additional reinforcement such as rebar may be placed in the space between the shell and the structure.