Failure Modes of Reinforced Concrete Beams Strengthened in Flexure with Externally Bonded Aramid Fiber-Reinforced Polymer Sheets under Impact Loading

This paper focuses on the aramid fiber-reinforced polymer (AFRP) sheet bonding method to investigate the influences of the sheet volume and input impact energy on the failure modes of strengthened RC beams. The drop-weight impact loading tests were conducted on RC beams strengthened with AFRP sheets. The sheet volume was investigated, varying from 415 to 1660 g/m(2). The impact force was generated by dropping a 300 kg steel weight onto the midspan of the beams from different heights (0.5, 1.0, 2.0, 2.5, 3.0, and 3.5 m), and the weight's drop height was raised until the sheets were debonded or ruptured. As a reference beam, nonstrengthened beams were also evaluated. The following are the findings of this research. (1) In the event of impact loading, the impact resistance capacity of strengthened beams can be enhanced by up to 85% by applying the AFRP sheet bonding method; however, (2) in the case of relatively large impact energy, the impact resistance capacity may not always be remarkable. (3) Depending on the sheet volume, the failure mechanism of the AFRP-strengthened beams was classified into two types: sheet debonding and sheet rupturing. Furthermore, (4) increasing the sheet volume may not improve the debonding of the AFRP sheet of the strengthened beams.