Research on Flexural Performance of Truss-Reinforced Composite Slabs with a Single Rectangular Rib

Truss-reinforced concrete composite slabs (TRCs) are extensively applied in prefabricated construction, but the limited stiffness of precast base plates may lead to excessive deformation and cracking during construction. This study investigates the truss-reinforced concrete composite slab with a single rectangular rib (TRC-SR) to improve flexural performance. A three-dimensional nonlinear finite element model was developed and verified through experimental results. The validated model was then used to compare the staged responses of TRCs and TRC-SRs and to evaluate the effects of rib height, rib width, precast base plate thickness, truss reinforcement diameter, and truss reinforcement height during the construction and service stages. The results show that the rectangular rib significantly enhances construction-stage stiffness under construction live load, and the maximum mid-span deflection decreases from 26.7 mm for TRC to 9.6 mm for TRC-SR, corresponding to a reduction of 64.0%, while plastic strain is also reduced and more localized. Rib height and precast base plate thickness are the dominant parameters governing construction-stage deformation, whereas the service-stage flexural performance is particularly sensitive to base plate thickness. A simplified method for calculating short-term flexural stiffness was further proposed based on transformed section theory and the average stiffness approach. For 12 parametric models, the mean ratio of finite element to theoretical deflection was 1.027, with a coefficient of variation of 7.57%. The results demonstrate the effectiveness of the rectangular rib in improving construction-stage flexural performance and provide useful references for the design optimization of TRC-SR precast base plates.