Sustainable precast composite deep beams including concrete with partial replacement (50%) of recycled coarse aggregate

Three new sustainable models of a hybrid deep beam have been proposed in this work, which are the curved (CRV) and the arched (ARC1) and the modified arched (ARC2) in addition to the conventional (HRL) hybrid model that used recycled coarse aggregates (RCA) instead of natural aggregates. This work included using the steel fiber concrete (SFC) is used in regions of high stress only. The effects of hybridization types and effect of inclination of stirrups have been considered as the parameters of the study. Results revealed that the failure capacity was increased by 8%, 22%, 21%, and 22%, for the for hybrid models respectively. On the other hand, the specimen (CTRL-SFC) showed a 19% enhancement. Regarding the flexural toughness, enhancement in 13%, 39%, 34%, 71% for the hybrid models respectively compared to the non-hybrid model (CTRL-R50). The respective enhancement for the specimen (CTRL-SFC) was 52%.For the effective stiffness, results showed small range of enhancement (1.5–9)%. It is evident that the specimens’ internal reinforcement detailing is adequate to stop the semi-diagonal mode of failure, which is an extremely brittle mode of failure. Furthermore, a replacement rate of up to 50% does not significantly affect the overall response. Moreover, the results of the tests indicated that the inclined alignment of the stirrups prevented diagonal cracking more than their vertical alignment. The proposed curved and arched models may be used with multi-concentrated loads, prestressed beam, precast walls. The proposed models aimed to produce lightweight/sustainable/low cost/high performance precast deep beams with compared to the horizontal hybrid model.