Small-Scale Modeling of Reinforced Concrete Structural Elements for Use in a Geotechnical Centrifuge

This paper discusses the modeling of reinforced concrete structural elements for use in geotechnical centrifuge modeling of soil-structure interaction problems. Centrifuges are employed in geotechnical modeling so that the nonlinear constitutive behavior of soil in small-scale models can be correctly modeled at prototype scale. Such models typically necessitate large scale factors of between $1:20$ and $1:100$, which is significantly larger than most conventional small-scale structural modeling. A new model concrete has been developed consisting of plaster, water, and fine sand as a geometrically scaled coarse aggregate that can produce a range of model concretes with cube compressive strengths between 25–80 MPa. Reinforcement is modeled using roughened steel wire (beams) or wire mesh (slabs). To illustrate the validity of the modeling technique, a series of three- and four-point bending tests were conducted on model beams designed to represent a $0.5\times 0.5\mathrm{m}$ square section prototype beam at $1:40$ scale, and model slabs designed to represent a prototype slab with plan dimensions of $4.8\times 4.8\mathrm{m}$ and 0.4 m deep (also at $1:40$ scale). The amount of longitudinal reinforcement was varied and tests both with and without shear reinforcement were conducted. The models were able to accurately reproduce both shear and flexural (bending) failures when loaded transversely. The load capacity (strength), bending stiffness, and ductility were shown to be simultaneously and appropriately scaled over a range of scaling factors appropriate for geotechnical centrifuge testing, and the technique therefore provides a significant improvement in the ability to accurately model soil-structure interaction behavior in centrifuge models.