Structural Engineering Slide Library
Bridge trusses: Lift bridge
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Image-GoddenD8 Lift bridge, Sacramento River Delta. This simple bridge is used to introduce many aspects of truss bridge design. Details are shown in GoddenD9-D17. A Warren truss with verticals is used throughout. Lift span is simply supported. The double spans on each side are determinate due to internal pins. (Near Rio Vista, California) | |
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Image-GoddenD9 Lift bridge, Sacramento River Delta. Lift span shown partially raised. Note the counterweights that balance the lift span have dropped to the mid-height of the towers. (Near Rio Vista, California) | |
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Image-GoddenD10 Close-up of the towers. In a direction parallel with the bridge axis the bracing consists of a Warren truss, and in the other direction it is a K-truss. (Near Rio Vista, California) | |
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Image-GoddenD11 Lift bridge, Sacramento River Delta. Side spans consist of a 2-span Warren truss. There are three pins in the truss on the near side of the central pier which make the spans determinate. (Near Rio Vista, California) | |
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Image-GoddenD12 Lift bridge, Sacramento River Delta. View through the Warren truss. This shows the overhead transverse bracing and its connection to the Warren truss. Overhead members in the horizontal plane consist of transverse sway frames and oblique members completing a K top lateral truss. This bracing makes the truss torsionally stiff, and stiffens the top chords of the Warren truss against lateral buckling. (Near Rio Vista, California) | |
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Image-GoddenD13 Lift bridge, Sacramento River Delta. Close-up of the side span at the central pier support. Note the 3 pin connections in the truss to the right of the support; two in the top chord and one in the bottom chord. The left pin in the top chord is also a sliding connection, hence the two trusses are hinges about the lower pin. It is an example of cantilever and suspended span construction. (Near Rio Vista, California) | |
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Image-GoddenD14 Lift bridge, Sacramento River Delta. Lower chord connection. Typical riveted connection between lower chord and three web members meeting at this node point, using gusset plates on both sides of the truss chord. (Near Rio Vista, California) | |
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Image-GoddenD15 Lift bridge, Sacramento River Delta. Joint detail between Warren truss and overhead sway frame. This slide also shows one of the pin-connections. (Near Rio Vista, California) | |
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Image-GoddenD16 Lift bridge, Sacramento River Delta. Detail of fixed hinge bearing in the bridge. (Near Rio Vista, California) | |
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Image-GoddenD17 Lift bridge, Sacramento River Delta. Detail of rocker bearing at the abutment end of the side span. (Near Rio Vista, California) |
Set D: Truss Structures
