Enhancing the performance of precast hybrid concrete deep beams using curved and arched designs : experimental investigations

In recent years, deep beam performance improvement has garnered significant interest, leading to several proposed solutions. This study introduces and compares two new models of hybrid concrete deep beams, aiming to outperform conventional designs. Nine experimental specimens were subjected to one-point and two-point static loadings. The specimens shared identical dimensions, with an overall span of 1700 mm, width of 180 mm, and overall depth of 450 mm. Response parameters such as cracking and failure loads, failure modes, crack propagation rates, toughness, stiffness, and ductility were evaluated. Results indicated substantial enhancements compared to the conventional hybrid model. The curved model achieved a 5 % and 12 % increase in failure load under one-point and two-point loading, respectively. The corresponding enhancements for the arched model were 13 % and 20 %. Notably, toughness improvements ranged from 32 to 39 % and 97 % under two-point loading for the curved and arched models, respectively. Ductility gains were 39 % and 45 % under two-point loading and (45-57)% and 74 % under one-point loading for the respective models. The findings highlight the potential of the curved model with reactive powder concrete-normal strength concrete (RN) composition, offering increased load-carrying capacity and the possibility of using low-strength concrete for cost and weight reduction. The arched model also demonstrated significant enhancements. Changing the loading configuration from two-point to one-point resulted in reduced capacity, but the proposed models mitigated this reduction. This study contributes valuable insights into the behaviour of precast hybrid concrete deep beams, showcasing the superior performance of the proposed curved and arched models.