During their lifetime, civil structures are expected to provide safety against failure as well as appropriate serviceability under expected workloads and conditions of use. As the load-carrying characteristics and serviceability of the structure may diminish with time due to ageing and to environmental influences, the structures may lose their designed functions partially or wholly. Appropriate actions should then be implemented to improve the performance of structures and restore the desired function of structures. Toward this end, repair and strengthening are the two major approaches. There are several definitions of repair and strengthening of structures given by different professional organizations.