Numerical Study on the Bending Performance of Steel-Ribbed Composite Slabs for Substations

This study investigates the bending behavior of steel-ribbed composite slabs for a 500 kV substation project in China through numerical simulation. The unidirectional bending performance of the slab was first analyzed and validated against theoretical calculations. After that, the bidirectional bending performance of double-spliced and triple-spliced composite slabs were evaluated against the monolithic slab, followed by a parametric analysis to identify the influence of key factors. The results indicate that the steel-ribbed composite slabs feature high cracking strength, post-crack stiffness, bearing capacity, and commendable ductility under both unidirectional and bidirectional loading conditions. Under unidirectional loading, the ultimate capacity of the slab reaches 57–58 kN/m2. Under bidirectional loading, the cracking load and bearing capacity of the dense-splicing composite slabs increase by more than 60% compared with unidirectional loading. Composite and monolithic slabs exhibit similar crack patterns and ultimate capacities under bidirectional loading; however, the presence of splicing joints results in a slight increase in the ultimate deflection of the double-spliced and triple-spliced composite slabs by 7.53% and 7.75% compared with that of the monolithic slab. The ratio of prestressing steel is identified as the most critical parameter for failure control, followed by the concrete strength. When the strength of the joint-connecting rebars exceeds 235 MPa and the diameter is greater than 4 mm, transversal force transfer across the joints is reliable. This paper provides valuable insights and practical guidance for the prefabricated construction of substations.