Seismic retrofit of RC frames through beam-end weakening in conjunction with FRP strengthening

The strong column/weak beam requirement is now widely accepted in the design of reinforced concrete (RC) frames to achieve good seismic performance. However, many existing RC frames violate this requirement as they were designed according to inadequate design codes (generally previous codes). In particular, RC frames designed according to the previous Chinese codes for seismic design are likely to violate this requirement as the contribution of a cast-in-place floor slab in tension is not included in assessing the moment capacity of the beam in negative bending. This paper proposes three promising beam weakening techniques in combination with FRP strengthening to achieve this strong column/weak beam hierarchy and presents the preliminary results of an ongoing study into the effectiveness of and design procedures for the proposed techniques.