General Information

Figure 1 shows a beam bridge.

Beam bridge.
Beam bridge over a river
Main span ≅ 20 m
Girder Prestressed concrete box-beam

Double-Column Pier

Figure 2 shows a schematic lateral view of the pier arrangement.

Lateral view.
Arrangement of piers of a prestressed box-beam bridge.

The total bridge length (l) is about 220 m. There are eleven spans and ten double-column piers (1 to 10), and the foundation consists of a pile cap and piles. The pile caps are placed on two elevation levels (A and B). The pier configuration is based on its height and includes tie beams and RC members; the latter are installed on piers 5 to 9 on elevation A . Figure 3 shows pier 10, figure 4 shown pier 4, and figure 5 shows pier 5.

Pier 10 (short double-columns).
Double-column pier with short columns

The columns have a height h ≅ 40 cm, and the piles are partially embedded in the ground.

  • What are some possible reasons to install the pier cap and the short double-columns instead of the pile cap under the girders?

  • Pier 4.
    Double-column pier with tie beams

    A pile cap uses about eighteen cubic meters of reinforced concrete.

    Pier 5.
    Double-column pier of a prestressed box-beam bridge

    The column height (h) is about 6.5 m. The RC members are installed between the pile caps and the pier caps and have the same geometry as a pile cap; that gives a mass of 45 tons per RC member (RC density assumption of 2500 kg/m3).

  • What is the purpose of the RC members installed on piers 5 to 9?