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.