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
Strength I
Flexure
1.29
1.30
1.67
1.69
Shear
2.44
3.16
Strength II
Service II
1.21
1.22
1.57
1.58
Exterior Girder
1.40
1.37
1.81
1.77
3.05
3.14
3.95
4.08
1.48
1.38
1.92
1.8
ASD HS20
HS20
0.74
0.76
1.35
LFD HS 20
1.33
2.22
2.26
Serviceability
1.19
1.25
1.98
2.01
Example A2 – Simple Span Reinforced Concrete T beam
LRFD HL 93
0.59
0.77
0.85
1.10
ASD HS 20
0.91
0.97
1.54
0.88
1.47
1.51
Example A3 – Simple Span Prestressed Concrete I-Girder bridge
Flexure (as midspan)
1.91
Shear (at 64 in)
1.96
1.12
-
Shear (at 20 ft)
3.04
Service III
Flexure (at midspan)
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
Interior Stringer
LRFR Mode
Strength I Limit State
0.35
0.37
0.45
0.48
1.07
1.08
1.39
Example A5 – Four Span Continuous WPG bridge
Flexure at 0.4L (+M)
0.96
0.94
1.24
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
2.27
2.34
1
1.01
1.3
1.32
1.1
1.11
1.44
1.26
1.64
Example A6 – Single Span Through Pratt Truss bridge
MBE A6
Design Load Rating (HL-93)
Top Chord TC4
1.97
2.04
Bottom Chord BC4
1.85
Diagonal D1
Vertical V1
2.4
Example A7 – Simple Span Reinforced Concrete Slab bridge
Strenghth I
0.63
0.64
0.82
0.83
LFD HS-20
HS-20
Details
MR
MD
MLL+I
0.17
0.29
52
12.4
95.7
Example A8 – Simple Span Two Girder Steel bridge
MBE A8
Floorbeam
Max +M
1.13
1.46
Max -M
2.42
1.6
2.07
Flexure Max +M (Governs)
1.06
1.27
Girder
1.89
2.45
2.12
Example A9 – Simple Span Prestressed Concrete Adjacent Box Beam bridge
MBE A9
1.61
1.65