Experimental investigation on anchoring and bonding properties between Fe-SMA strip and concrete

Abstract

In the technical system of the previous investigations, the prevalent method for external prestressed strengthening of concrete structures with iron-based shape memory alloy (Fe-SMA) strips is mechanical anchoring (without bonding). However, there is currently a lack of research on the adhesively bonded situation. In order to enhance the comprehension of the mechanical behavior of Fe-SMA/concrete joints, a total of 18 lap-shear test specimens were meticulously prepared, encompassing three distinct anchorage methods (single anchor-bolt anchorage, single-adhesive anchorage, and hybrid anchorage). The test series encompasses three varying bond lengths (300 mm, 350 mm, and 400 mm), three different activation temperatures (non-activated state, 200 ℃, and 300 ℃), as well as three diverse numbers of anchor bolts (1 bolt, 2 bolts, and 3 bolts). The bond-slip relationship before and after thermal activation was analyzed based on the data obtained from digital image correlation (DIC) tests. The results indicated that two or more anchors ensured strip rupture, exerting 40 % of its tensile strength. Single-adhesive bonding results highlighted the necessity for preventing debonding. The hybrid-anchorage method with anchor bolts and adhesive exerted 47 % strip strength and higher bond-slip stiffness. At 200 ℃ activation temperature, the interface rupture energy of the single-adhesive bonded specimen increased by approximately 30 %, but decreased by 22 % at 300 ℃. This paper provided an important reference for external prestressed strengthening of concrete structures with Fe-SMA strips under different situations.