General Information
Figure 1 shows a truss bridge that is used by motorcycles, bicycles and pedestrians.
| Main span | ≅ 10 m |
| Type | Underslung truss bridge |
| Truss material | Steel |
| Truss height | ≅ 0.3 m |
| Deck width | ≅ 1.2 m |
Truss Geometry
Figure 2 shows a side view of the main span.
The truss is made of rectangular hollow sections, the height h ≅ 0.3 m, and the verticals' spacing b ≅ 1 m. The diagonals are connected to the verticals, and the inclination angle α ≅ 9°.
Would there be a structural safety or serviceability problem without the diagonals?
Cross-Frame
Figure 3 shows a bottom view of the bridge.
The deck is made of timber planks; they are connected to the upper chords and a stringer, which is connected to a cross-frame that consists of five members: two horizontals (1 and 2) and three verticals (3 to 5). The horizontals (1 and 2) are connected to the verticals and bottom chords of the trusses. Figure 4 shows a bottom view of a cross-frame to truss connection.
The horizontals (1 and 2) and the truss are connected by welding; the former does not touch the latter.
What is the purpose of members 2, 3, 4, and 5?
Alternative Variant
Figure 5 shows a schematic three-dimensional view of the used bridge and a beam bridge variant with I-section girders.
The truss is continuous, while the beam bridge model consists of three simply supported beams. The deck and the stringers are equal on both bridges, while cross-beams are installed in the beam bridge instead of cross-frames.