Longitudinal Stress-Laminated Girder Bridges

Longitudinal stress-laminated girder bridges consist of a number of horizontally glued laminated girders, placed side by side over supports, then compressed transversely by high-strength prestressing rods.

Load transfer between girders is by compression and friction rather than by adhesive or mechanical connections. Prestressing rods are at regular intervals through prebored holes at the neutral axis of the girders; each rod may be stressed in tension to 80,000 to 100,000 pounds using a hydraulic jack.

Such stress-laminated girder bridges behave as a continuous slab. The girders are of kiln dried lumber, finger jointed into laminations full span, then assembled with stronger and stiffer laminations on the tension and compression flanges. Such bridges are an excellent economical design for 30-60 ft. spans. Dry use stresses are used for design of girders.

Camber can easily be built into the span by placing camber in the individual girders at time of manufacture. More than a single wood species can be used, with the stronger and stiffer wood being placed on the tension and compression flanges.


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Bridges Page 4