Adjustable module for variable depth steel arch bridges

• A new strategy for modular, steel construction is developed: an adjustable module.
• Methodologies for form development of rational variable depth arches are presented.
• Geometry of the adjustable module to scribe variable depth forms is evaluated.
• Three dimensional finite element models demonstrate the promise of the module.
• Results show adjustable module increases material efficiency and has a reduced weight.

This paper presents a new strategy for modular steel construction: an adjustable module. Existing rapidly erectable, steel panelized bridge systems (e.g., Bailey, Acrow, Mabey-Johnson) have limited material efficiency (span squared per weight) as they are comprised of rigid modules in a girder-type configuration. This paper addresses this limitation by developing a new adjustable, steel module comprised of a four-bar linkage which can form more efficient variable depth arch bridges. The objectives of this study are to (1) present methodologies for the development of rational variable depth three- and two-hinged arch forms, (2) evaluate the geometry of the adjustable module to scribe these rational forms, and (3) demonstrate the promise of the adjustable module through three-dimensional finite element analyses. Results show that a lightweight, adjustable module can form variable depth three- and two-hinged arches which increase the material efficiency by a factor of approximately 3 compared to existing systems. The module and other arch components can be comprised of American Institute of Steel Construction Steel Construction Manual standard rolled section sizes, thereby forming a versatile, kit-of-parts systems. The module weighs 1.41 times less than a conventional module, suggesting significant advancement compared to existing practice.