1. ETCULVERT EXAMPLE

2. ETCULVERT Design Process
Project Data
Update Reinforcing
Design Mode
Optimize
Geometry & Matls
Print / Review
Loading
Design Parameters
Review / Optimize
Switch to Analysis

3. STEP 1 – PROJECT DATA SCREEN 3-3 New Project AASHTO LRFD ASTM C1577
Select Culvert Type
Rebar and Mesh are both allowed; User preference based on manufacturing requirements
Single Cell Precast w/ 4 Sides. Per Section 6.5, the standard RCB designs provided in Table 1 are based on mesh with 4” maximum spacing of circumferentials. Sections 6.5 and 11.6 allow for Grade 60 rebar for longitudinal distribution reinforcement. Section 6.5 and 11.6 also allow the use of Grade 60 rebar provided the design values of Table have been increased accounting for yield strength, steel spacing, concrete cover and crack control.

4. Enter in Project or Job information and description into ET Culvert.
STEP 1 – PROJECT DATA
SCREEN 3-4
Enter in Project or Job information and description into ET Culvert.

5. Select LRFD Specification Select LRFD Specifications
STEP 2 – DESIGN MODE
SCREEN 3-5
Project Settings
AASHTO LRFD
ASTM C1577
Specifications
Select LRFD Specification
Select LRFD Specifications

6. State /Agency/Locality
STEP 2 – DESIGN MODE
SCREEN 3-5
Project Settings
AASHTO LRFD
ASTM C1577
State /Agency/Locality
Allows the user to pre-define design criteria for specific agencies that have established criteria that differs from AASHTO LRFD or ASTM C1577.

7. STEP 2 – DESIGN MODE SCREEN 3-5
Always do the initial design in “DESIGN MODE”, then toggle over to “ANALYSIS MODE” to tweak the design

8. ASTM C1577 is a precast box culvert specification.
STEP 2 – DESIGN MODE
SCREEN 3-5
ASTM C1577 is a precast box culvert specification.

9. Select units based on project requirements.
STEP 2 – DESIGN MODE
SCREEN 3-5
Select units based on project requirements.

10. STEP 3 – GEOMETRY & MATLS SCREEN 3-6 Culvert Properties AASHTO LRFD
ASTM C1577
No. Boxes:
Project Specified
Per 1.1, Single-celled RCB only.
Clear Span, ft.
Project Specified, Standard designs for even ft. increments.
Clear Height, ft.
Length, ft.
Sections & , RCB sections having a length less than 4 ft., edge beams required; User preference per mfg. equipment
Not specified; User preference per mfg. equipment
Fill Depth, ft.
(Maximum)
Project Specified. Standard designs provided for 20 ft. to 35 ft. depending on RCB size.
Minimum Fill Depth, ft.
Project Specified. Standard designs provided for 0 ft to 2 ft. of fill.
Increment, ft.
Project Specified. Standard designs for: 0’<2’; 2’<3’, 3’-5’, 10’, 15’, etc.

11. Slab and Wall Dimensions, in. Added Thickness for V-Bottom Slab
STEP 3 – GEOMETRY & MATLS
Slab and Wall Dimensions, in.
AASHTO LRFD
LRFD Table
ASTM C1577
Top Slab
Min. = (S+10)/30 >/= 0.54 ft. & , Precast Box Culverts, Span : Slab Thickness = (s/t) </= 18. (Note: In-lieu of stated criteria, deflection analysis required.)
See Tables for standard thickness. Special and Modified thickness allowed per Section 7.2.
Bottom Slab
----
See Tables for standard thickness. Special and Modified thickness allowed per Section 7.2
Exterior Wall
Added Thickness for V-Bottom Slab
Top Haunch
Bottom Haunch
SCREEN 3-6

12. STEP 3 – GEOMETRY & MATLS

13. STEP 3 – GEOMETRY & MATLS SCREEN 3-6 Skew Angles, deg. AASHTO LRFD
ASTM C1577
Culvert:
Section & considers parallel and perpendicular applied LL. However, LL distribution need not be corrected for skew effects per
Per X1.2.3, If the live load travel is at an angle greater than 30 deg from parallel to the span and the fill height over the RCB is 5 feet and less, a separate skew analysis must be performed.
All C1577 standard designs based on a 0 degree culvert skew angle.
Left End:
NA – For Cast In Place RCB Only.
Right End
SCREEN 3-6
Bottom Slab Support
AASHTO LRFD
ASTM C1577
Full Bottom Slab
Section applies to box culverts (cast in place & precast) and cast-in-place reinforced concrete arches.
Section 1.1, applies only to single-cell precast reinforced concrete box sections (4 sided) cast monolithically.
No Bottom Slab, Pinned Supports
NA for four sided RCB
No Bottom Slab, Fixed Supports

14. SKEW ANGLE IN ETCULVERT ONLY IMPACTS THE
AASHTO DOES NOT DEFINE THE SKEW ANGLE, AASHTO ONLY CONSIDERS PARALLEL AND PERPENDICULAR APPLIED LIVE LOADS.
PERP (>60)
SKEW ANGLE IN ETCULVERT ONLY IMPACTS THE
SKEWED PORTION OF A CULVERT WHERE THE
EFFECTIVE SPAN LENGTH CHANGES
30 < CHECK BOTH < 60
PARALLEL (<30)

15. STEP 3 – GEOMETRY & MATLS SCREEN 3-7 Concrete AASHTO LRFD ASTM C1577
Strength (f’c)
Per Section –
2.4 ksi to 10.0 ksi for normal weight concrete
5,000 psi minimum
Density
Per Table & Comentary C3.5.1, Varies Linerly with concrete strength; 5.0<f'c</=15.0 ksi; Density = (f'c)
150 pcf (min.)
Elasticity, Ec
LRFD ; Varies as a function of concrete unit weight;
Ec = 33,000(K1)Wc^1.5(f'c)^0.5
Per LRFD
Concrete Type
Per Table Normal weight concrete

16. STEP 3 – GEOMETRY & MATLS SCREEN 3-7 Reinforcement Cover AASHTO LRFD
LRFD & 2013 Interim
ASTM C1577
Exterior of Top Slab
Per Specifications Table Top slabs used as a driving surface minimum reinforcement cover = 2.5"; top slabs with less than 2.0' of fill, minimum reinforcement cover = 2.0"; top slabs with under fills greater than 2.0' otherwise 1.0"
ASTM C inches of concrete cover for top slabs under fills of 0' to 2' in depth; 1.00 inch for slabs under fill greater than 2'
Exterior of Bottom Slab
1.0”
Exterior of Exterior Wall
Interior of Top Slab
Interior of Bottom Slab
Interior of Exterior Wall

17. Reinforcement Diameter, in User input initial estimate
STEP 3 – GEOMETRY & MATLS
Reinforcement Steel
AASHTO LRFD
Section
ASTM C1577
Yield (fy) ksi
Reinforcing bars, deformed wire, cold-drawn wire, welded plain wire fabric, and welded deformed wire fabric shall conform to the material standards as specified in Article 9.2 of the AASHTO LRFD Bridge Construction Specifications. The nominal yield strength shall be the minimum as specified for the grade of steel selected, except that yield strengths in excess of 75.0 ksi shall not be used for design purposes. Bars with yield strengths less than 60.0 ksi shall only be used with the approval of the owner. Per Section – smooth WWF the yield strength may be taken at 65 ksi; for deformed the yield may be taken at 70 ksi.
Standard Design Tables of ASTM C1577 based on reinforcement yield strength, fy = 65,000 psi
Allow Stress, ksi
NA - per C
100% of yield stress
Elasticity (Es) ksi
29,000 ksi per LRFD
---
Reinforcement Diameter, in
User input initial estimate
Shear Steel Yield, ksi
Up to 100 ksi per LRFD
SCREEN 3-7

18. Industry standard is 120 pcf per ASTM C1577
STEP 3 – GEOMETRY & MATLS
SCREEN 3-7
Soil
AASHTO LRFD
LRFD &
ASTM C1577
Density
In the absence of precise project information, Table may be used. Soil min. = 100 pcf.
Industry standard is 120 pcf per ASTM C1577

19. STEP 3 – GEOMETRY & MATLS SCREEN 3-7 Exposure Factor AASHTO LRFD
ASTM C1577
Class 2 Exposure
0.75 for Class 2 exposure unless other wise specified.
Select 0.75 for Class 2 exposure (see C )

20. STEP 3 – GEOMETRY & MATLS SCREEN 3-7 Soil Structure Interaction
AASHTO LRFD
LRFD
ASTM C1577
Compacted Fill
Fe = (H/Bc), however Fe shall not exceed 1.15 for installations with compacted fill along the RCB sides, LRFD
(Project specific-user input required)
ASTM C1577, Table X1.1 assumes compacted
side fill,
Fe = (H/Bc)
Fe Max. = 1.15
Uncompacted Fill
Fe = (H/Bc), however Fe shall not exceed 1.40 for installations with uncompacted fill along the RCB sides LRFD
---
User Defined
Per LRFD Trench varies as a function of trench width; Installations other than embankment or trench based on previous experience, tests, or soil-structure interaction analysis.

21. Section X1.1.2, X1.3.3 & Table X1.1, granular soil,
STEP 3 – GEOMETRY & MATLS
SCREEN 3-7
Slope Factor
AASHTO LRFD
Table a-1
2013 Interim Spec
ASTM C1577
Granular Soil – All culverts and buried structures, except concrete pipe
1.15
Section X1.1.2, X1.3.3 & Table X1.1, granular soil,
LL Dist. = 1.15

22. STEP 4 – LOADING SCREEN 3-8 Live Load AASHTO LRFD ASTM C1577 Truck
Per LRFD to , to , & Design truck, design tandem and design lane load. These may be modified by a given jurisdiction when: legal loads are significantly greater than typcial HL93; roadway is expected to carry unusually high percentages of truck traffic; traffic flow controls are in place; Special industrial loads are common.
HL93

23. SCREEN 3-9 Live Load AASHTO LRFD ASTM C1577 HL93
LRFD Figure
Figure X1.1
SCREEN 3-9

24. Box needs to be checked to include Tandem Load
Live Load
AASHTO LRFD
ASTM C1577
HL93
Box needs to be checked to include Tandem Load
SCREEN 3-9

25. Standard Designs do not include lane load
Live Load
AASHTO LRFD
ASTM C1577
HL93
AASHTO LRFD does not require a lane load. However, some DOT agencies specify that lane load is to be applied
Standard Designs do not include lane load
SCREEN 3-9

26. SCREEN 3-9 Only Matters if Lane Load is Included Live Load AASHTO LRFD
ASTM C1577
HL93
AASHTO LRFD requires that both the Truck and Tandem loads be checked.
SCREEN 3-9
Only Matters if Lane Load is Included

27. (Project specific-user input required)
STEP 4 – LOADING
SCREEN 3-8
Live Load
AASHTO LRFD
ASTM C1577
Traffic Direction
Per LRFD Section Parallel & Perpendicular to span
(Project specific-user input required)
Section X1.2.3 –Std. designs based on parallel to culvert span – perpendicular to span when The skew angle is greater than 30 degrees and the fill is less than 5 feet.

28. (Project specific-user input required)
STEP 4 – LOADING
SCREEN 3-8
Live Load
AASHTO LRFD
ASTM C1577
Max. Number of Lanes
Per LRFD Section , in general are determined by taking the integer of w/12, where w = width of clear roadway.
(Project specific-user input required)
So long as the direction of traffic is parallel to main reinforcement, input the number of lanes = 1

29. STEP 4 – LOADING SCREEN 3-8 Live Load AASHTO LRFD ASTM C1577
Override MPF
Section
Don’t override MPF
Per Section X1.1 MPF = 1.2 for one lane
Depth of LL Surcharge
Table <2‘
(enter depth of SC if different for agency)
enter depth of SC if different for agency
Apply LL Surcharge at Fill Depth Greater Than 2 Foot?
Table YES, Apply LL surcharge at fill depths greater than 2 feet
(Check Box)
Include Lane Load?
Per LRFD Section , box culverts are exempted from lane loads regardless of span and regardless of span orientation (transverse or longitudinal) to the direction of traffic
(Do not check box)
See Section X1.2.2
Neglect LL for Fill Depths Greater Than 8 Feet and Greater Than Span Length
Per LRFD Section , for single span culverts, the effects of live load may be neglected where the depth of fill is more than 8 feet.
(User’s preference)
C1577 considers live load for the full depth, Appendix X1.

30. STEP 4 – LOADING SCREEN 3-8 Dead Load AASHTO LRFD ASTM C1577
Additional Uniform DL, klf
Per Section 3.5.1, Dead Loads, the dead load shall include the weight of all components of the structure, appurtenances and utilities attached thereto, earth cover, wearing surface, future overlays and planned widening.
(Project specific-user input required)
Earth Load Only
Future Wearing Surface,
klf
For bituminous wearing surfaces, kcf
(Table )

31. (Project specific-user input required)
STEP 4 – LOADING
SCREEN 3-8
Concentrated Loads
AASHTO LRFD
ASTM C1577
Loads 1 to 3
The width of the top slab strip used for distribution of concentrated wheel loads, specified in Article shall also be used for the determination of moments, shears and thrusts in the side walls and the bottom slab.
(Project specific-user input required)

32. STEP 4 – LOADING SCREEN 3-8 Lateral Soil Loads AASHTO LRFD 3.11.5.1;;
ASTM C1577
Soil Equivalent Fluid Pressure, pcf
The equivalent-fluid method may be used where Rankine Earth Pressure Theory is applicable where the backfill is free-draining.
(Project specific-user input required)
User to Input:
Max. = 60
Min. = 30

33. STEP 4 – LOADING SCREEN 3-8 Fluid Pressures AASHTO LRFD ASTM C1577
Consider Internal Water Pressure
Include fluid weight contained in the box culvert.
TYPICAL

34. Live Load Strength Factor
STEP 5 – DESIGN PARAMETERS
Load Factors
AASHTO
ASTM C1577
LRFD Table
Table X1.1
DC (max./min.)
1.25 / 0.9 “
DW (max./min.)
1.5 / 0.65
EV (max./min.)
1.3 / 0.9
EH (max./min.)
1.35 / 0.9 WA 1
 Live Load Strength Factor
LRFD Table
LL-Strength I
1.75
LL-Strength II
1.35
SCREEN 3-12

35. Operational Importance LRFD Section 1.3.5 & Section 12.5.4
STEP 5 – DESIGN PARAMETERS
Load Modifiers
AASHTO
ASTM C1577
Ductility LRFD
Section & Section
1.00 for conventional design and details complying with LRFD specifications
Redundancy LRFD
Section & Section
Non-redundant under earth fill = 1.05; Redundant under live load and dynamic load allowance = 1.0
Operational Importance LRFD Section & Section
1.00 for typical bridges
SCREEN 3-12

36. STEP 5 – DESIGN PARAMETERS
Capacity Modifiers
AASHTO
ASTM C1577
Condition
1.00 for conventional design and details complying with LRFD specifications
---
System
Non-redundant under earth fill = 1.05; Redundant under live load and dynamic load allowance = 1.0
SCREEN 3-12

37. STEP 5 – DESIGN PARAMETERS
Resistance Factors
AASHTO 
ASTM C1577
Shear
0.9 per LRFD Table
0.90
Moment
1.00 per LRFD Table
1.00
P-M Diagram
Compression
Tension
SCREEN 3-12

38. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Member Thickness
AASHTO
 ASTM C1577
Top Slab
LRFD Table : Traditional Depths for Constant Depth Structures, Minimum Depth = (S+10)/30 >/= 0.54 ft. & Section , Precast Box Culverts, Span to Slab Thickness (s/t) </= 18.
Fixed
Bottom Slab
---
Exterior Wall
Interior Wall

39. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Live Load Analysis
 AASHTO LRFD
 ASTM C1577
Automatically Set Direction to Account for Skew Effects?
No LRFD
Include Impact on Bottom Slab
Yes, Per LRFD the width of the top slab strip used for distribution of concentrated wheel loads, shall be used for the determination of moments, shears and thrusts in the side walls and bottom slab.
Override DLA Dynamic Load Allowance?
No Table
DLA Dynamic Load Allowance
Per LRFD Section Buried Components covered by Section 12, in percent, shall be taken as IM=33( De)> 0%

40. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Live Load Analysis
 AASHTO LRFD
 ASTM C1577
Limit Distribution Width to Culvert Length for Fills Less Than 2 Feet?
YES, per LRFD Section – Interim Spec.
Check Box
Limit Distribution Width to Culvert Length for Fills Greater Than 2 Feet?
NO, per LRFD Section –Interim Spec. Do Not Check Box.
Do Not Check Box.
Combine Axle Overlaps for Fills Greater Than 2 Feet
User –
Check Box.
Always Distribute Wheel load?
????????
Axle Increment for Analysis
See ET Culvert User Manual
----

41. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Reinforcement
 AASHTO LRFD
  ASTM C1577
Individual Top and Bottom Slab Design?
Yes 
Yes
Individual Interior and Exterior Wall Design?
 NA NA
Always Include Distribution Steel?
Do not check
Max. As Used
in Vc Calcs,

42. Miscellaneous Options
STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Miscellaneous Options
 AASHTO LRFD
  ASTM C1577
Use Strength II
Do Not Check Box

43. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Live Load Deflection Criteria
 AASHTO LRFD
ASTM C1577 
1/800,1/1000, User Defined
LRFD Section , Criteria for Deflection
1/800 – Non Pedestrian App.
1/1000 – Pedestrian App.
(Project Specified)
----

44. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Slenderness
 AASHTO LRFD
ASTM C1577 
Check Slenderness
LRFD
----

45. Bottom Left Node on Rollers
STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Structural Modeling
 AASHTO LRFD
ASTM C1577 
Use Haunches
Yes – Check Box
Bottom Left Node on Rollers
User Preference

46. Extend Critical Sections Use Max Moment w/ Max Shear
STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Critical Sections
 AASHTO LRFD
ASTM C1577 
Consider Haunches
Yes – Check Box
Extend Critical Sections
Use Max Moment w/ Max Shear
User preference

47. STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Flexure
 AASHTO LRFD
ASTM C1577 
Ignore Axial Thrust
Do Not Check Box
Use Pipe Equation

48. Always Check Iterative Beta
STEP 5 – DESIGN PARAMETERS
SCREEN 3-14
Shear
 AASHTO LRFD
ASTM C1577 
Always Check Iterative Beta
Do Not Check Box

49. STEP 5 – DESIGN PARAMETERS
SCREEN 3-15

50. STEP 5 – DESIGN PARAMETERS
SCREEN 3-17
Design Mode does not investigate shear reinforcement – concrete is assumed to provide only means of shear resistance. Shear reinforcement is only reviewed in Analysis Mode.

51. STEP 6 – REVIEW / OPTIMIZE
Reduce the length of the text report:
CLICK <<FILE>>
CLICK <<OPTIONS>>

52. STEP 6 – REVIEW / OPTIMIZE
Review Input Data

53. STEP 6 – REVIEW / OPTIMIZE
Review Input Data – continued…..

54. STEP 6 – REVIEW / OPTIMIZE
Review Input Data – continued…..

55. STEP 6 – REVIEW / OPTIMIZE
Overall Design Results (slab thicknesses and reinforcing areas)
Modify Spacing to 2” (plant standard)
Adjust As, prv based on actual sizes

56. STEP 6 – REVIEW / OPTIMIZE
Review Flexural Design each depth increment
Consider reducing As1

57. STEP 6 – REVIEW / OPTIMIZE
Review Shear Design each depth increment
Could reduce slab thickness – but plant has 8” forms as a standard – could also reduce concrete strength required

58. STEP 7 – SWITCH TO ANALYSIS
SCREEN 3-5

59. STEP 8 – UPDATE REINFORCING

60. OK @ 2’ – check other depths
STEP 9 – OPTIMIZE
Reduced As1 from 0.30 to 0.24
2’ – check other depths

61. Change Steel Yield or Concrete Strength
STEP 9 – OPTIMIZE
Problem with Mcr check
Change Steel Yield or Concrete Strength

62. STEP 9 – OPTIMIZE
fc = 4.5ksi or fy = 65 ksi

63. Reduced Concrete Strength (lower MOR)
STEP 9 – OPTIMIZE
Reduced Concrete Strength (lower MOR)

64. Increased Steel Yield Strength
STEP 9 – OPTIMIZE
Increased Steel Yield Strength

65. STEP 10 – PRINT / REVIEW Switch back to Full Length Report:
CLICK <<FILE>>
CLICK <<OPTIONS>>

66. STEP 10 – PRINT / REVIEW

67. STEP 10 – PRINT / REVIEW

68. STEP 10 – PRINT / REVIEW

69. STEP 10 – PRINT / REVIEW