Modular Joint for the Accelerated Fabrication and Erection of Steel Bridges

This paper introduces a new strategy for the accelerated fabrication and erection of steel bridges: a modular joint. The modular joint is a prefabricated, nodal connector composed of a weldment/built-up section of webs and flanges that includes a starter segment for each connecting member. It joins standard rolled wide flange sections through bolted splice connections in double shear. Flanges and webs are connected independently, forming a moment-resisting connection. This provides flexural stiffness for truss-like or beam-like behavior and provides the potential for the structure to tolerate member loss. The flange splice plates connecting the joint and any member can be bent to varying angles to achieve a variable depth geometry. This is a “kit-of-parts” approach, where members are standard sections and the prefabricated modular joint can be repeated throughout a single structure and also used for many structures. Although this approach retains all the advantages of modular construction (e.g., prefabrication, mass production, rapid erection, and reusability), it overcomes the prime deficiency of the existing technologies that a fixed panel size limits the span length. This paper investigates this approach through (1) developing a methodology to achieve rational constant- and variable-depth bridge forms, (2) performing structural optimization for minimum self-weight while meeting structural performance demands and transportability criteria, and (3) demonstrating the promise of this approach through detailed finite element numerical analyses.