The vast majority of precast segmental bridges are erected span-by-span with overhead and underslung self-launching gantries. Twin-girder overhead gantries provide unrivalled flexibility of operations in large-scale highway bridges, light-rail transit bridges with box girders and dual-track U-spans, urban bridges in median, marine operations, and other conditions of reduced clearance under the bridge.
In 31 pages in full A4/letter format, Span-by-Span Erection of Precast Segmental Bridges: Twin-Girder Overhead Self-Launching Gantries explores the main components of a twin-girder overhead gantry, the pros and cons of modular trusses and box girders, the use of hangers and spreader beams to hold the segments in-place during application of epoxy, and the support and launch systems of the gantry. The eManual also discusses loads, self-launch kinematics, performance, productivity, span cycle times, the labor demand of different temporary static schemes of staged construction, and the pros and cons of simultaneous erection of adjacent decks by side shifting the gantry from bridge to bridge on wide pier crossbeams.
The eManual explores the stability of tall bridge piers under the loads applied by brackets supporting the front pendular leg of the gantry, the stiffness interactions to consider for the design of bridge piers and superstructures, and staged application of post-tensioning to avoid opening of the epoxy joints and the risk of brittle span failure.
The eManual provides exhaustive coverage of the topic for bridge owners, designers and construction professionals interested in span-by-span construction of precast segmental bridges. Other monographs of the eManuals Project discuss segment fabrication, the span assembly operations common to all families of self-launching gantries, and the other types of self-launching gantries used for span-by-span construction.
The collection Span-by-Span Construction of Precast Segmental Bridges (134 pages) provides exhaustive coverage of the entire span-by-span construction process, ranging from segment fabrication by short- and long-line casting to the different types of self-launching gantries used for span erection, and is offered with a 10% discount on the cover price of the five eManuals.