Built-Up Press Brake-Formed Tub Girders

Abstract

This paper presents built-up press brake-formed tub girders (PBTGs) as a new approach for the fabrication of resilient, short-span steel bridges. In contrast to existing PBTGs that are cold bent from a single steel plate, this is a built-up system in which webs are cold bent and bolted to separate, flat bottom and top flange plates. It offers enhanced versatility, as this is a “kit-of-parts” where different sizes of components can be used to achieve required capacities or span lengths (e.g., thicker bottom flanges for negative moment regions, deeper webs for longer spans). Using built-up sections joined by bolts provides internal member redundancy, as crack propagation between components is arrested. The objectives of this paper are to: (1) introduce the system including design details; (2) numerically demonstrate its feasibility through the finite element modeling of two demonstration bridges; and (3) investigate the internal redundancy by evaluating behavior when a flange or web is abruptly lost. Results indicate the viability and redundancy of the system for simple and two-span continuous bridges.