Ultimate strength behaviour of reinforced concrete beams strengthened by aluminium-alloy plates

Abstract

This paper firstly proposed the new strengthening methods on reinforced concrete (RC) structures using the aluminium alloy (AA) plates. Then, the flexural behaviour of RC beams strengthened by externally bonded (EB) and mechanically fastened (MF) AA plates were studied through13 four-point bending tests. Four parameters were studied that included the strengthening method, thickness of AA plate, grade of AAs, and reinforcement ratio. Test results showed that the MF AA beams failed in flexure with concrete crushing, and the EB AA beam exhibited the bonding failure. Compared with EB AA beams, the MF AA beams exhibited larger load carrying capacity and ductility, but lower initial stiffness. Increasing the thickness of AA plate significantly improved the load carrying capacity, but slightly decreased the ductility of MF AA beams. The grade of AA plates exhibited weak influence on MF AA system since the strain of AA plate was significantly limited by the AA plate hole-anchor gap. The strengthening effect was more significant for RC beams with a relatively lower reinforcement ratio. Moreover, theoretical models were proposed to evaluate the ultimate carrying capacity of MF AA beams that considered the strengthening AA plate-concrete slips. Validations of the theoretical predictions against test results showed that they predicted reasonably on the ultimate load carrying capacity of strengthened RC beams by AA plate.