Prestressed/post-tensioned concrete bridges - Computational Analysis and Design of Bridge Structures - page 142

A B C

Midspan

T4

T3

T3

T1

A B C

(a)

Flat square
anchor plate
system

T3

T3

T2

T2

T1

T1

T4 T4

T3

T2

T1

(b) End view A-A Section B-B Section C-C

Figure 5.15 Post-tensioning (a) layout and their (b) cross sections at the end span of a
continuous precast prestressed/post-tensioned concrete bridge.

1. Erect precast prestressed beams on early-made concrete abutments
and supports

2. Install duct splices for post-tensioning tendons and pour beam splices
and diaphragms at piers. At this stage, stress and grout tendons T1

3. Pour in-span diaphragms. At this stage, stress and grout post-tension
tendons T2

4. Pour deck. At this stage, stress and grout tendons T3 for full
post-tensioning

5. Construct sidewalk and barrier/railing and complete the job

In the process three 2D beam models with different section properties are
built. The first noncomposite sectional model with different levels of ten-
don forces is used for stages 1, 2, and 3. The second short - term composite
sectional model with full tendon forces is used for stage 4, whereas the
third long - term composite sectional model with full tendon forces is used
for stage 5. Note here that short - term and long - term composite sections are
used by AASHTO to refer to the section properties of n and 3 n , respectively,
where n is the modulus ratio between steel and concrete materials. For the
consideration of pretensioning/post-tensioning tendon modeling and its