This document summarizes the design of a pre-tensioned prestressed concrete bridge and a post-tensioned two-way concrete slab. For the bridge, Tx70 girders were selected with 32 total girders and 1248 prestressing strands. The design met strength and serviceability requirements. For the slab, a 4-span slab with 24 prestressing strands in 6 bands of 4 strands each was designed. The final design stresses were below allowable limits. Work was distributed among group members for the bridge and slab designs, modeling, calculations, and reporting.

1. Prestressed Concrete
(CE 5309)
Term Project
Group 2
Spring 2016
University of Texas at Arlington

2. PART 1
PRE-TENSIONED PRESTRESSED BRIDGE
DESIGN

3. IH-35W Bridge 205

4. Design Information
 Overall width of bridge = 53 ft; roadway width = 51 ft
 Limit maximum Girder length to 120 ft
 TxDOT T551 rail – 382 plf
 Typical composite cast-in-place deck with 8” thick and f’c= 4 ksi, Ec = 3605 ksi
 Girders with ultra-high concrete strength – f’ci = 20 ksi,
f’c = 30 ksi, Ec = 9872 ksi
 PGSuper V 2.9.0.9
 TxDOT 2013 Bridge Design Manual

5.  Geometry
 8 Number of spans
 Exterior spans - 105 ft.
 Interior spans - 115.06 ft.
 Tx70 girders selected
 Most economical
 Least weight
 Least number of girders
 4 girders spaced at 16' on center
Design Parameters

6. PGSuper Model

7. Strand Layout, Span 8 Girder A
Section @ Mid-SpanSection @ Left-End Section @ ¼ Span

8. Shear Layout

9. Concrete Strength

10. Deck Properties and Overlay
Weight

11. Design Results of Various Girders
Model Num
ber
Girde
rs
Strand
Dia (in)
Weight
of
Beam
(kip/ft)
Number of strands
(Exterior spans)
Number of strands
(Interior spans)
Total
Number
of
Strands
Total
weight of
girders
(kips)
Total
number
of
girdersExternal
Girders
Internal
Girders
External
Girders
Internal
Girders
Tx 54 6 0.6 0.88 24 28 30 34 1496 38030.78 48
Tx 54 7 0.6 0.88 24 24 28 30 1572 44369.25 56
Tx 62 5 0.6 0.98 24 28 30 34 1236 35293.72 40
Tx 62 6 0.6 0.98 22 24 26 28 1264 42352.46 48
Tx 62 7 0.6 0.98 22 22 24 26 1376 49411.208 56
Tx 70 4 0.7 1.04 32 40 36 44 1248 29963.65 32
Tx 70 5 0.7 1.04 24 24 24 28 1032 37454.56 40
Tx 70 6 0.7 1.04 22 24 22 24 1120 44945.472 48

12. Final Design
 Tx70, total 32 girders
 1248 strands
 No de-bonding used
 Grade 270, Low-relaxation 0.7" strands
 Additional mild steel reinforcement used
 TxDot standard details used for shear design
 f‘ci = 20 ksi, f‘c = 30 ksi

13. Distribution of L.L for span 8
• From hand calculation = 1.256
• Difference = 8.7%

14. Moment Capacity at Mid-span
Exterior Girder – End Span

17. Comparison of Multiple Loads Moments
And Moment Capacity

18. Comparison of Multiple Loads
Shear And Shear Capacity

19. Multiple Loads Displacement

20. Ahmed, Haroon Rasheed
 Girder Design (Tx 40 and 46)
 Drawings,
 PowerPoint Presentation
Bichewar, Namrata
 Girder Design ( Tx 70)
 Live Load Moment Distribution Factor
Emami Saleh, Arash (Team Leader)
 General Model
 Moment Calculations,
 PowerPoint Presentation
Okagbare, Oghenekevwe Christabel (Team Leader)
 Girder Design ( Tx 28 and Tx 34)
 Drawings
 Project Report
 PowerPoint Presentation
Shaltoof, Mohammad Abed Mohammad
 Girder Design( Tx 54 and 62)
 Moment Calculations
 PowerPoint Presentation
Distribution of Work

21. PART 2
POST-TENSIONED TWO-WAY SLAB DESIGN

22. Overall Second Level Plan

23. Design Parameters
Concrete Properties
 Slab Thickness = 8 inches
 F’c = 4,000 psi, Ec = 3605 ksi
Prestressed Steel Properties
 ½” dia. Grade 270 low-relaxation strands
 Initial Prestress = 0.8 * fpu
Loading
 Superimposed Dead Load = 20 psf
 Superimposed Live Load = 40 psf
ACI 318-11 used as design code

24. Design Consideration
 4 – span condition utilizing wall as an exterior
support
 Equivalent Frame Method
 Software Inputs

25. Software Input
 12’ floor to floor heights above & below
 24” square columns
 Exterior shear walls modeled to same width of design strip
 Slab assumed to be fixed-fixed at boundary condition
 Average Precompression range 125 psi to 300 psi
 Percentage of Dead Load to balance 25% to 200%
 Post-Tension Strand Cover: 1.5” top
2.0” bottom
 Mild Reinforcement Cover: 1.0” top & bottom

26. Tributary Area

27. Tributary Area (Cont…)

28. Loading on the slab

29. ADAPT Rendering

30. Final Design Stresses
Max Tensile Stress = 0 x √(f’ci) < 3 x √(f’ci) OK
Max Compressive Stress = 0.164 x f’ci < 0.6 x f’ci OK
Number of tendons : 24 ( 6 – bands with 4 in each )

31. Final Design Stresses
Sustained Load Stresses
Total Load Stresses

32. Stress Diagram
-450
-400
-350
-300
-250
-200
-150
-100
-50
0
50
100
150
200
SPAN1 SPAN2 SPAN3 SPAN4
Stress Diagrams
Project: "TermProject" / LoadCase:SERVICE_1_Max_LL
+1.00SW+0.30LL_Max+1.00SDL+0.30XL +1.00 PT +0.00HYP+0.00LAT
Tensile Stress Positive
Stress[psi]
AllowableStresses Top

33. Tendon Profile
FINAL DESIGN: 15 – ½”, Grade 270 Low-Relaxation strands

34. Mild Steel Profile

35. Tendon layout
24 strands – 4/band
Shear
stud layout

36. Distribution of Work
Al Mutar, Sudad Saeed
• Model,
• Hand Calculations
• Project Report
• Presentation
Kadam, Kshitij Chandrakant
• Model
• Hand Calculations
• Project Report
• Presentation
Mazumder, Md Shahadat Hossain –
• Building Model and Bridge General Model
• Shop Drawings
• Project Report
• Presentation