Title: An Investigation on Transversely Prestressed Concrete Bridge Decks
1An Investigation on Transversely Prestressed
Concrete Bridge Decks
2Objective
- Study of transverse post-tensioning of concrete
bridge decks as an alternative to improve
durability.
3Types of Bridges in Indiana
4Scope
- Develop design specifications applicable to
- Slab bridges
- Slab-on-Girder bridges
5Problem Statement
q F/L
s?
Assumption Linear behavior
6Specimen for Experimental Phase of Texas Study
Location of strain gages
1.2ksi
0.6ksi
1.2ksi
7(No Transcript)
8Comparison of Analytical (SAP2000) Experimental
(Texas Study) Results
Modeling Type
Top Stresses
3D(III)
3D(II)
3D(I)
2D
14
14
14
16
m
42
38
38
40
Max
m mean(ss/sexp)-1x100
Max Max(ss/sexp)-1x100
9Analysis using ANSYS 5.7
- Alternative modeling
- Use brick and shell elements
10SAP2000 vs. ANSYS 5.7(Texas Model)
11Variables of Interest
- Girders (spacing, stiffness)
- Diaphragms (spacing, stiffness, location)
- Boundary conditions
- Post-tensioning spacing
- Slab thickness
12Base Case
22 in.
13Preliminary Evaluation of Variables (2D Modeling)
14Preliminary Evaluation of Variables (2D Modeling)
a) Half Spacing
b) Quarter Spacing
15Preliminary Evaluation of Variables (2D Modeling)
- Effect of Girder (No diaphragms)
a) Concrete girders
b) Steel girders
16Preliminary Evaluation of Variables (2D Modeling)
Top half diaphragms present
Bottom half diaphragms no present
17Preliminary Evaluation of Variables (2D Modeling)
- Effect of boundary conditions
18Preliminary Evaluation of Variables (2D Modeling)
- Effect of Post-tensioning Spacing
a) Forces at every other node
b) Forces every four nodes
_at_ 4
_at_ 8
19Preliminary Evaluation of Variables (2D Modeling)
8 slab
6 slab
20Preliminary Identification of Relevant Variables
(2D Modeling)
- Diaphragms (stiffness, location, spacing)
- Boundary conditions
- Post-tensioning spacing
21Effect of Diaphragms
- Distribution of transverse stresses is mainly
affected by diaphragm size and location.
22Notation
Normalized stress ss/q
y
x
23Effect of Diaphragm Size
y
y
Stripe 1
Stripe 2
24Effect of Diaphragm Location(Exterior Diaphragms
Only)
y
y
Stripe 2
Stripe 1
25Minimum Stress vs. Diaphragm Position
26Effective Width of T Beam vs. Top Stress
Beff
27Diaphragm Location vs. Effective Width
28Conclusions at this Stage
- Distribution of transverse stresses mainly
influenced by - Diaphragm axial stiffness and position
- Boundary conditions
- Influence of diaphragm position Rationalized
using T-beam analogy