Abstract
Owing to their high corrosion resistance, aluminium alloy (AA) plates bonded with magnesium phosphate cement (MPC) are considered as a viable candidate for reinforcing inshore infrastructures that are subject to severe environmental conditions and vapor atmospheres. Therefore, the aim of this study is the evaluation of the flexural behaviour of simple beams that are strengthened using this technique. Six unbonded posttensioned concrete (UPC) beams with different reinforcement ratios are damaged by static loads and then repaired and strengthened using AA plates. The failures under two-point loading are then investigated. Thereafter, a simplified method is proposed for the evaluation of the flexural strength of a UPC beam strengthened by an AA plate with MPC. The flexural strengths of the six specimens increase by an average of 14%, and the displacement ductility factor decreases by an average of 34.14%. Moreover, the increase and decrease ratios are proportional and inversely proportional to the comprehensive reinforcement index, respectively. The influences of the three main factors on the flexural strength of the AA plate are determined: the increase in the stress of the unbonded tendons, stress at the midspan and slippage at the ends of the AA plate, and increase ratio of the flexural strength. It shows that the AA plates bonded with MPC can be used successfully in concrete strengthening.
Highlights
Concrete structures are generally subject to significant external stimuli such as shock, vibration, and overload, which result in local damages to buildings during flexural or shearing processes
Numerous experiments and analyses have verified the effectiveness of thin steel plates and fibre-reinforced polymer (FRP) sheets in the mechanical strengthening of concrete structures
Compared with steel and FRPs, the aluminium alloy (AA) plate is preferable due to its lower weight than steel, with a similar tensile strength and ductility, in addition to a higher ductility than FRP, similar flexural strength, and comparable corrosion resistance. erefore, the AA plate is considered as an excellent material for external bonding and strengthening
Summary
Concrete structures are generally subject to significant external stimuli such as shock, vibration, and overload, which result in local damages to buildings during flexural or shearing processes. A common countermeasure involves the external bonding of these concrete structures with composite materials, thin steel plates, or other reinforcements. Numerous experiments and analyses have verified the effectiveness of thin steel plates and fibre-reinforced polymer (FRP) sheets in the mechanical strengthening of concrete structures. Given that steel is susceptible to corrosion in wet or vapor atmospheres, the bonding strengths at the interfaces of steel plates and concrete may be degraded, weakening the strengthening effect. Erefore, the AA plate is considered as an excellent material for external bonding and strengthening. It is limited by the use of epoxy as the adhesive, which is disadvantageous due to its low temperature and aging resistance, in addition to its pungent odour and toxicity. Magnesium phosphate cement is preferable as a potential replacement of epoxy as the main adhesive for structural strengthening in the high-temperature
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