Structural Behavior of Rubberized Engineered Cementitious Composite Beam-Column Joints under Cyclic Loading

This study investigates the structural behavior of rubberized engineered cementitious composite (ECC) beam-column joints wider cyclic loading. The e f fect of using different supplementary cementitious materials (SCMs) and different sand types on the cyclic behavior of ECC joints is also investigated. The main parameters were the percentage of crumb rubber (CR) (0%, 5%, 10%, and 15% by volume of sand), type of Sails (metakaolin [MK], silica fume [SLF], and fly ash [FA]), and type of sand used (silica sand and natural sand). The investigation also tested a conventional normal concrete with 10 mm (0.39 in.) coarse aggregate size for comparison. The beam-column joint in this study was designed according to strong-column/weak-beam concept to put more focus on the ductile failure rather than brittle failure. The structural performance of tested beam-column joints was evaluated based on the load-deflection envelope response, hysteresis behavior; initial stiffness, deformability, cracking behavior; displacement ductility, brittleness index, energy dissipation, first cracking load, and ultimate load. The results indicated that increasing the percentage of CR up to 15% significantly increased the joint deformability, cracking behavior; ductility, and energy dissipation, while the initial stiffness, first crack load, and ultimate load were decreased. Replacement of E4 (commonly used in standard ECC) with MK/SLF slightly reduced the beam-column joints' defirmability, ductility, and energy dissipation while the first cracking load, initial stiffiless, and ultimate load significantly increased. The results also revealed that although replacing silica sand with natural sand had an insignificant effect on the compressive and splitting tensile strengths of ECC, it showed a negative effect on the deformability, ductility, energy absorption, first cracking load, initial stiffness, and ultimate load of beam-column joints.