High-load multi-rotational disc bearings for highway bridges: A review of design criteria, material behavior, and existing testing protocols

High-Load Multi-Rotational (HLMR) disc bearings are essential in modern highway bridge systems, providing the capacity to transmit large vertical reactions while accommodating the rotations and translations induced by thermal movements, traffic loading, wind, braking, and seismic effects. Despite their extensive use throughout the United States, current design provisions in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications remain largely based on National Cooperative Highway Research Program (NCHRP) Report 432 (1999), a document developed using data from a single manufacturer. As a result, today’s diverse range of disc bearing products, material formulations, and manufacturing practices are not adequately represented in national standards. This paper presents a comprehensive review of existing practices and standards, with a primary focus on the U.S. regulatory and design framework, drawing upon a broad set of technical sources that include national specifications (AASHTO LRFD and the AASHTO Steel Bridge Bearing Guidelines), foundational research documents (NCHRP Report 432), engineering manuals (American Iron and Steel Institute (AISI) Steel Bridge Design Handbook), state Department of Transportation (DOT) design manuals and bulletins, available published academic research, and proprietary manufacturer design and testing documentation. The review highlights substantial structural and material limitations within existing guidance, including outdated design expressions, the absence of product-neutral qualification and acceptance testing standards, insufficient treatment of viscoelastic deformation and sliding interface deterioration, and a lack of comprehensive material property data needed to calibrate and validate modern LRFD-based analytical and numerical models. While the identified gaps and proposed recommendations are predominantly grounded in U.S. design practice, the underlying technical challenges, including the need for standardized testing, material characterization, and performance-based design criteria, are broadly applicable to international bridge bearing practice.