Cyclic behaviour of squat reinforced concrete shear walls strengthened with ultra-high performance fiber reinforced concrete

Abstract

Ultra-high performance fiber reinforced concrete (UHPFRC) is now available as an advanced building material for strengthening applications. It is characterized by high strength, ductility, fracture toughness, and good durability. This paper presents an experimental investigation conducted on seismically shear-deficient squat reinforced concrete (RC) shear walls strengthened with casting UHPFRC layers/jacket subjected to lateral quasi-static reversed cyclic loading and a constant axial load. The experiment was conducted on four identical rectangular RC shear walls with a scale of ⅓, an aspect ratio of 1.5 and having low concrete strength. As a reference sample, one of the shear walls was not strengthened with UHPFRC while the other three were strengthened with UHPFRC using different configurations as (i) one layer only on one long side, (ii) two layers on the long sides, (iii) all sides of the wall (jacket). Digital image correlation (DIC) technique was utilized for assessment of the damage mechanism of all specimens. According to the results, the strengthening techniques significantly improved the lateral load strength, ductility, and energy dissipation capacities especially for RC walls strengthened with UHPFRC jacketing. Results indicated the occurrence of debonding failure for the wall strengthened with two UHPFRC layers. The shear and flexural strength capacities of identical wall specimens strengthened with reference concrete were evaluated according to ACI 318 code and their efficiency was compared with test results of UHPFRC strengthened walls. The UHPFRC strengthened techniques increased the lateral load carrying capacities by 70% to 227% of the original wall.