Since the wide cracks or large deflections can have a significant effect on the appearance of concrete elements and may cause some uncommon behavior, therefore, serviceability of concrete structures requires investigation. The main objective of this paper is to study experimentally the serviceability of continuous reinforced concrete (RC) beams strengthened by Ni-Ti strands. In addition, some building code provisions were used to calculate crack width and deflection. The current study presents the experimental results to verify the accuracy of building codes’ provisions for continuous RC beams strengthened by SMA strands. Although a pattern of smaller width cracks was monitored for strengthened beams, more than 50% of the crack widths were recovered because of super elastic SMA strands. The performance of crack width provisions illustrates an overestimated crack width for SMA RC beams. Moreover, the predicted values for immediate deflections based on building codes provided a good agreement, although the effective reinforcement ratio (steel reinforcement and SMA strands) had a significant effect on immediate deflections of reinforced concrete beams strengthened by SMA strands under service loads.
Although cracking is normal in reinforced concrete structures, caution should be exercised to prevent impairment of the proper function or durability of the structures or cause an unacceptable appearance in the structures. Consequently, crack width calculations have been especially observed in service limit states. Recently, smart materials such as shape memory alloys (SMAs) are considered in civil engineering. SMAs are a class of metallic alloys that have the unique property of being able to undergo large amounts of plastic strain while remaining elastic. The main objective of this paper is to investigate the crack pattern of continuous reinforced concrete (RC) beams strengthened by Ni-Ti strands. Experimental service crack widths were compared with theoretical values obtained from building codes provisions and formula proposed by previous literature. It was shown that superelastic strands had a significant effect on the occurrence of cracks and so the cracking moment of SMA RC beams increased. Verification of theoretical equations virtually resulted in overestimated crack widths for strengthened beams. Besides, the high recovery capacity of crack widths is the most important superiority of SMA RC beams.
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