Prestressed/post-tensioned concrete bridges - Computational Analysis and Design of Bridge Structures - page 168

1640/2 1640/2

45

375

100

Section at midspan

Section at piers

375

Figure 5.48 Typical section of the box girder (cm).

T31 Cantilever tendons in top slabs T1s T1

T31

F31

F27 F27 F31

T32 T33

Z15

F1 F1

B5 Z1

B7

B7

B1

Cantilever tendons in webs

Piers

B1~4,B6 Closure tendons in central span

Closure tendons in side span
Figure 5.49 Segments and layout of tendons in the continuous rigid frame of Sutong
Bridge approach spans.

W3 W2 W1

13.500 200 13.500

Figure 5.50 Layout of the preparatory external tendons in the continuous rigid frame of
Sutong Bridge approach spans.

Two sets of additional tendons are designed to avoid excessive deflections
due to uncertainties including material properties, concrete creep and shrink-
age, and prestress losses. The first set is the internal tendons preset in the
bottom slabs, and the other set is the external preparatory tendons. Both sets
would be applied after closure or during service if necessary. As shown in
Figure 5.49, there are a total of 15 internal tendons (Z1-Z15) in the bottom
slab in the main span. Z1 through Z5, Z7 through Z9, Z11 through Z13,
and Z15 are applied immediately after closure, and the rest are anticipated
to be applied one year after the bridge is in service. As shown in Figure 5.50,