Shear behavior of RC slender beams without stirrups by using precast U-shaped ECC permanent formwork

ECC characterized by its strain-hardening behavior in tension, high tensile and compressive strain and cracking control capacity is an ideal material for permanent formwork of reinforced concrete (RC) beams. This study investigated the shear behavior of RC slender beams without shear reinforcements by using precast U-shaped ECC permanent formwork. A total of 10 beams, including 1 RC beam for reference and 9 beams using U-shaped permanent formwork with different thicknesses and interfacial properties were fabricated and tested. ECC permanent formwork with three different thickness, namely 15, 20 and 25 mm, respectively were precast. At each thickness of permanent formwork, three different interfacial properties, namely smooth interface, anchored interface and rugged interface, respectively were prepared to investigate the effects of interfacial properties. All beams were tested by four-point loading tests to investigate the shear behavior and failure mechanism. The experimental results revealed that the shear carrying and deformation capacities of RC slender beams without stirrups could be enhanced significantly by using U-shaped ECC permanent formwork. The predictive equations for shear carrying capacities of RC beams without stirrups by using precast U-shaped ECC formwork were also proposed based on modified truss model and it agreed well with experimental result. (C) 2020 Elsevier Ltd. All rights reserved.