Retrofitting reinforced concrete beams by bolting steel plates to their sides. Part 1. Behaviour and experiments

A procedure has been developed for bolting steel plates to the sides of exi sting reinforced concrete beams which can be used to increase the shear str ength of beams, increase the flexural strength of beams with enhanced ducti lity or with only a small loss of ductility, and increase the stiffness of beams in order to reduce deflections and crack widths. It will be shown in this paper, through a qualitative analysis and through the results of testi ng eight large scale beams, that standard rigid plastic analysis techniques which are commonly used in the design of reinforced-concrete, steel, and c omposite steel and concrete beams cannot be used directly to design composi te bolted-plated reinforced-concrete beams. In the companion paper, quantit ative procedures will be used to adapt the standard rigid plastic analysis techniques for this relatively new form of retrofitting.