Flexural performance of unreinforced ECC I-beams with steel plate-bolts and FRP sheets connection: Experimental and numerical analysis

Engineered Cementitious Composites (ECC) exhibit excellent tensile ductility, cracking resistance, and high durability, holding great promise for applications in the field of unreinforced construction. Compared to conventional reinforced concrete structures, ECC in unreinforced construction can significantly improve construction efficiency and reduce labor costs. Therefore, it is imperative to validate the feasibility of ECC in unreinforced structures. Unlike conventional reinforced concrete structures, which rely on rebars to transfer tensile loads, ensuring robust connections between unreinforced ECC components becomes a critical challenge for structural safety. To investigate reliable connection methods for unreinforced ECC components, experimental tests were carried out in this study on the flexural behavior of unreinforced ECC I-beams connected with fiber reinforced polymer (FRP) sheets and steel plates-bolts assemblies in the midspan and shear-span regions. The results indicated that for I-beams with midspan FRP connections, when the FRP width was increased from 50 mm to 200 mm, the cracking load of the specimens increased by 28.8 %, mainly due to the confinement effect of the FRP on the ECC. The influence of the shear-span connections on the ultimate deflection of the specimens was less significant than that of the mid-span connections, and the location of the connection had a minimal effect on the load-bearing capacity. Due to the presence of clearance between the bolt holes and bolts, the initial stiffness of specimens connected using steel plates-bolts assemblies was generally lower than that of specimens connected with FRP sheets. The flexural capacity of the I-beams connected using FRP sheets and steel plates-bolts assemblies typically exceeded 90 % of that of cast-in-place beams, demonstrating the reliability and feasibility of the proposed connection method. Furthermore, a refined numerical model of the beam was developed using ABAQUS, and the simulated failure modes and load-displacement curves demonstrated close agreement with the experimental results, thereby validating the accuracy and feasibility of the finite element simulations.