General Information

Figure 1 shows a two-lane road beam bridge.

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

Piers and Bents

Figure 2 shows a side view of a bridge sector.

Beam bridge.
Beam bridge with different superstructure support types

There are two types of superstructure supports: A and B. Type B appears only once. Supports type A and B are shown in figures 3 and 4, respectively.

Support type A.
Beam bridge: single column pier

Support type A consists of a single column pier and a pier cap; the foundation consists of a pile cap and piles.

Support type B.
Three-column bent and bent cap with two units

Support type B consists of a three-column bent—the central column is shorter—and a bent cap, which is made of an upper and a bottom unit. The foundation of each column consists of a pile cap and piles.

  • What are some possible structural reasons for support type B?