LARS Bridge Result Comparison to MBE Examples
LARS Bridge has been run using MBE examples A1-A9 to compare results. Upcoming LARS version 6.00.01.01 was used in this comparison. The results are summarized below with any pertinent qualifications.
In general the comparisons are good. Variances occur due differences in:
Example A1 – Simple Span Composite Steel Stringer bridge
LRFD HL93 | |||||
Interior Girder | |||||
Limit state |
Design Load Rating | ||||
Inventory |
Operating | ||||
MBE |
LARS |
MBE |
LARS | ||
Strength I |
Flexure |
1.29 |
1.30 |
1.67 |
1.69 |
Shear |
2.44 |
|
3.16 |
3.16 | |
Strength II |
Flexure |
|
|
|
|
Shear |
|
|
|
| |
Service II |
1.21 |
1.22 |
1.57 |
1.58 | |
Exterior Girder | |||||
Limit state |
Design Load Rating | ||||
Inventory |
Operating | ||||
MBE |
LARS |
MBE |
LARS | ||
Strength I |
Flexure |
1.40 |
1.37 |
1.81 |
1.77 |
Shear |
3.05 |
3.14 |
3.95 |
4.08 | |
Strength II |
Flexure |
|
|
|
|
Shear |
|
|
|
| |
Service II |
1.48 |
1.38 |
1.92 |
1.8 | |
ASD HS20 | |||||
Interior Girder | |||||
HS20 | |||||
|
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | ||
Flexure |
0.74 |
0.76 |
1.35 |
1.38 | |
LFD HS 20 | |||||
Interior Girder | |||||
HS20 | |||||
|
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | ||
Flexure |
1.33 |
1.40 |
2.22 |
2.26 | |
Serviceability |
1.19 |
1.25 |
1.98 |
2.01 |
Example A2 – Simple Span Reinforced Concrete T beam
LRFD HL 93 | |||||
Limit state |
Design Load Rating | ||||
Inventory |
Operating | ||||
MBE |
LARS |
MBE |
LARS | ||
Strength I |
Flexure |
0.59 |
0.59 |
0.76 |
0.77 |
Shear |
0.85 |
0.85 |
1.10 |
1.10 | |
ASD HS 20 | |||||
Interior Girder | |||||
HS20 | |||||
|
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | ||
Flexure |
0.91 |
0.97 |
1.54 |
1.57 | |
LFD HS 20 | |||||
Interior Girder | |||||
HS20 | |||||
|
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | ||
Flexure |
0.88 |
0.91 |
1.47 |
1.51 |
Example A3 – Simple Span Prestressed Concrete I-Girder bridge
Interior Girder | ||||
Limit state |
Design Load Rating | |||
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | |
Strength I | ||||
Flexure (as midspan) |
1.48 |
1.47 |
1.92 |
1.91 |
Shear (at 64 in) |
1.96 |
1.12 |
- |
|
Shear (at 20 ft) |
1.30 |
3.04 |
- |
|
Service III | ||||
Flexure (at midspan) |
1.22 |
1.43 |
- |
|
Note: Shear results between LARS and MBE cannot be compared as the MBE results used MCFT theory and LARS does not.
Example A4 – Simple Span Timber Stringer bridge
LRFD HL93 | |||||
Interior Stringer | |||||
LRFR Mode |
Design Load Rating | ||||
Inventory |
Operating | ||||
MBE |
LARS |
MBE |
LARS | ||
Strength I Limit State |
Flexure |
0.35 |
0.37 |
0.45 |
0.48 |
Shear |
1.07 |
1.08 |
1.39 |
1.39 |
Example A5 – Four Span Continuous WPG bridge
LRFD HL93 | ||||
Interior Girder | ||||
Limit state |
Design Load Rating | |||
Inventory |
Operating | |||
MBE |
LARS |
MBE |
LARS | |
Strength I |
| |||
Flexure at 0.4L (+M) |
0.96 |
0.94 |
1.24 |
1.22 |
Flexure at 0.5L (+M) |
1.05 |
1.03 |
1.36 |
1.34 |
Flexure at pier 2 (-M) |
0.99 |
1.17 |
1.28 |
1.52 |
Shear at pier 1 |
1.75 |
1.8 |
2.27 |
2.34 |
Service II |
| |||
Flexure at 0.4L (+M) |
1 |
1.01 |
1.3 |
1.32 |
Flexure at 0.5L (+M) |
1.1 |
1.11 |
1.43 |
1.44 |
Flexure at pier 2 (-M) |
1.17 |
1.26 |
1.52 |
1.64 |
Example A6 – Single Span Through Pratt Truss bridge
MBE A6 | ||
Limit state |
Design Load Rating (HL-93) | |
Inventory | ||
MBE |
LARS | |
Strength I |
| |
Top Chord TC4 |
1.97 |
2.04 |
Bottom Chord BC4 |
1.97 |
1.85 |
Diagonal D1 |
1.69 |
1.67 |
Vertical V1 |
2.4 |
2.27 |
Example A7 – Simple Span Reinforced Concrete Slab bridge
LRFD HL93 | |||||||
Limit state |
Design Load Rating | ||||||
Inventory |
Operating | ||||||
MBE |
LARS |
|
MBE |
LARS |
| ||
Strenghth I |
Flexure |
0.63 |
0.64 |
|
0.82 |
0.83 |
|
LFD HS-20 | |||||||
Interior Girder | |||||||
|
HS-20 |
Details | |||||
Inventory |
Operating |
MR |
MD |
MLL+I | |||
LARS |
LARS |
LARS |
LARS |
LARS | |||
Flexure |
0.17 |
0.29 |
52 |
12.4 |
95.7 | ||
Example A8 – Simple Span Two Girder Steel bridge
MBE A8 | ||||||
Floorbeam | ||||||
Limit state |
Design Load Rating | |||||
Inventory |
Operating | |||||
MBE |
LARS |
MBE |
LARS | |||
Strength I |
Flexure |
Max +M |
1.13 |
1.17 |
1.46 |
1.52 |
Max -M |
2.42 |
|
3.14 |
| ||
Shear |
1.6 |
1.43 |
2.07 |
1.85 | ||
Service II |
Flexure Max +M (Governs) |
1.06 |
1.27 |
1.38 |
1.64 | |
Girder | ||||||
Limit state |
Design Load Rating | |||||
Inventory |
Operating | |||||
MBE |
LARS |
MBE |
LARS | |||
Strength I |
Flexure |
1.11 |
1.27 |
1.44 |
1.64 | |
Shear |
1.89 |
1.64 |
2.45 |
2.12 |
Example A9 – Simple Span Prestressed Concrete Adjacent Box Beam bridge
MBE A9 | |||||
Limit state |
Design Load Rating | ||||
Inventory |
Operating | ||||
MBE |
LARS |
MBE |
LARS | ||
Strength I |
Flexure |
1.25 |
1.28 |
1.61 |
1.65 |
Service III |
1.35 |
1.22 |
- |
- | |