Development and capabilities of the universal panel tester for large-scale testing and constitutive characterization

Yousef Abu Amneh, Abdulrahman Salah, Dimitrios Kalliontzis, Tito Gómez

The Universal Panel Tester (UPT) at the University of Houston is a large-scale facility designed to investigate structural element behavior under multi-axial stress states. Since its establishment in 1988, the UPT has supported pioneering research that advanced shear and torsion theories as well as constitutive models for reinforced concrete, prestressed members, FRP-strengthened systems, and, more recently, fiber-reinforced cementitious composites (FRCC). By applying shear, torsion, axial load, and bending individually or in combination, the UPT can replicate the complex stress states present in large-scale elements of shear walls, bridges, nuclear containment vessels, and offshore platforms. This review paper consolidates the configuration and current capabilities of the UPT and documents a 2025 upgrade to its control and data acquisition systems, which introduced high-precision displacement control, synchronized multi-actuator operation, and improved signal processing. A mock panel test demonstrated the upgraded system, tracking commanded UPT actuator loads with a median within-bank standard deviation of 1.07% from the commanded target. The paper also reviews how UPT experiments have shaped constitutive theories for reinforced concrete, underscoring their role in model validation. Building on this history, the upgraded UPT is being prepared to support digital-twin modeling workflows for emerging infrastructure systems.