LARS Result Comparisons to MBE Examples


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

-

-