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This paper presents a numerical investigation of the behavior of steel bridges composed of modular joints during erection by incremental launching. The modular joint is a nodal connector made up of flat and cold bent steel plates that are joined to standard wide-flange members to form a truss-type bridge. Members and modular joints have flanges and webs that are connected independently by bolted splices, resulting in moment-resisting connections. This capability of the nodal connectors to transmit flexure enables a truss-type system to be incrementally launched and provides enhanced resiliency through system redundancy (i.e., the structure can tolerate the loss of a diagonal member). This paper specifically investigates logistics related to this kit-of-parts approach, focusing on transportation to site, “shaking out” of the steel components for erection, and erecting components while minimizing the need for high-capacity cranes. A high-fidelity, three-dimensional Finite Element (FE) model using shell elements that incorporates staged construction is used to understand the behavior of a 119-m (390-ft) two-lane vehicular bridge during incremental launching and in service. The focus is on evaluating the global behavior of the system and local behavior of the modular joints and the members. Results demonstrate the erection advantages of this novel modular approach. The detailed FE modeling approach is compared with a design-level model using frame elements, culminating in guidelines for design and analysis. 

This paper presents the development and numerical investigation of a novel form for resilient lattice bridges inspired by the Système Eiffel. While Gustave Eiffel is known for his major works of structural art (e.g., Maria Pia Bridge), he was also a pioneer in modular and rapidly erectable bridges that were used worldwide. His Système Eiffel consists of triangular modules, with each module being made up of angle sections. These are joined to one another in an alternating fashion, with adjacent modules rotated 180 degrees. The same module could achieve a variety of spans (6-21 m), and deeper versions were used for longer spans (up to 30.8 m). Inspired by Eiffel, but factoring in today’s economic and labor market, this research has developed a novel approach to modular lattice bridges. Specifically, this research harnesses Eiffel’s approach of rotating adjacent modules, but instead focuses on the connector as the module that joins standard sections. Importantly, the lattice-type layout provides the structure with system redundancy, meaning that the fracture of one member does not cause collapse. This paper presents the numerical investigation of these modular lattice bridges through finite element analyses, considering behavior under dead and live load, global stability, and performance when subjected to member loss.