Behaviour under cyclic loading of strengthened beams

All the beams, after receiving two cycles of static loading in order to create a pre-cracking condition, were strengthened in bending by partial jacketing and then subjected to cyclic loading until the completion of 2x106 cycles or the occurrence of fatigue failure. Following the cyclic loading, the beams that did not fail by fatigue were subjected to a static load up to failure. The main variables were the beam-jacket interface condition (smooth or rough), the flexural reinforcement ratio in the beam and in the jacket, and cyclic load amplitude.

On the basis of the obtained test results and the results of previous studies of similar beams tested only under static loading, the behavior of the strengthened beams is discussed and a proposal for the beam-jacket connection design is presented, for the cases of predominantly static and cyclic loading.