Behavior of beams strengthened with steel fiber RC overlays

Abstract

Strengthening of reinforced concrete beams using steel fiber reinforced concrete (SFRC) overlays has been investigated in the test program described in this paper. Two methods have been used to connect the overlays to the original beams, ie chemical and mechanical bonding. In the chemical bonding, 2-component epoxy resin bonding agent has been used. The mechanical bonding was achieved by welding the stirrups in the overlays to the stirrups in the original beams only near each support. In general, the weld bonded strengthened beams have achieved a better structural behavior in terms of load carrying capacity and failure mode compared to the epoxy bonded beams. The epoxy bonded beams have reached same load and ductility levels obtained from an identical monolithically cast control beam which was included in the test program for comparison purposes. However, at failure separation cracks have occurred at the common interface between the overlays and the original beams. On the other hand, the weld bonded strengthened beams have behaved in a flexural ductile manner and achieved higher load carrying capacity compared to the control beam. The interlaminar shear failure did not occur in these beams which have acted as a single unit up to the failure.