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TitleAN ANALYSIS OF THE US ARMY LIGHT VEHICLE / FOOT BRIDGE DESIGN by Stephen J ...
LanguageEnglish
File Size6.1 MB
Total Pages261
Document Text Contents
Page 1

AN ANALYSIS

OF THE

U. S. ARMY

LIGHT VEHICLE / FOOT BRIDGE

DESIGN

by

Stephen J. Ressler

Celal N. Kostem

Fritz Engineering Laboratory

Department of Civil Engineering

Lehigh University

Bethlehem, Pennsylvania 18015

May 1990

Fritz Engineering Laboratory Report No. 432.12

Page 2

TABLE OF CONTENTS

ABSTRACT . . 1
1. INTRODUCTION 3

1.1 Background 3
1.2 Purpose 5
1.3 Research Objectives and Scope 5
1.4 Analytical Approach . 6

1.4.1 General . . . . . . 6
1.4.2 Research Phases 8

1.4.2.1 Investigation of Composite Membrane Deck Behavior 8
1.4.2.2 Investigation of Bridge Behavior. 8

1.4.3 Guidelines for Finite Element Modeling 9

2. DESCRIPTION OF BRIDGE . . . . . . . . 10
2.1 Design Concept . . . . . . . . . . . . 10

2.1.1 General Configuration and Terminology 10
2.1.2 Employment . . 13
2.1.3 Trilateral Code . . . 14

2.2 Structural Details . . . . 15
2.2.1 Welded Connections . 15
2.2.2 Diagonal Cable Braces 16
2.2.3 Hinges and Latches 16
2.2.4 End Ramp Bays 17
2.2.5 Deck End Plates 18

2.3 Material Properties 18
2.3.1 Aluminum . . . 18
2.3.2 Steel . . . . . 19
2.3.3 Composite Membrane 19

2.3.3.1 Fiber Properties 20
2.3.3.2 Matrix Properties 21
2.3.3.3 Elastic Properties of Unidirectional Laminae . 22
2.3.3.4 Elastic Properties of the Membrane 24
2.3.3.5 Nonlinearity in the Membrane 25

2.4 Critical Members. . . . . . . . . . . . 26

3. DESCRIPTION OF FINITE ELEMENT MODELS 28
3.1 Finite Element Analysis Computer Programs. 28

3.1.1 The Finite Element Method . 28
3.1.2 SAP IV . . . . . 29
3.1.3 ADINA • . . . . 29

3.2 Membrane Deck Model 1.
3.2.1 Purpose. . . . .
3.2.2 Discretization
3.2.3 Nonlinear Truss/Cable Elements
3.2.4 Boundary Conditions.
3.2.5 Assumptions . .

3.3 Bridge Model 1
3.3.1 Purpose . . .
3.3.2 Discretization
3.3.3 Tubular Frame Members

IV

31
31
32
34
36
36
37
37
38
39

Page 130

UPRIGHT
<DETAIL B >

COMPOSITE
MEMBRANE
DECK

CROSS
MEMBERS

<DETAIL C>

TOP.
CHORD

<DETAIL Al

n
7.5" 15.0"

~------------4_ ·_ ~o· I
.,__ _____ 3 7 . 0. ------4

0.188. l
0. 1 25. 2.376"

J
l--J. 0 ·----l

l . • 10.878"

Figure 2. Typical Cross Section of the Center Bay

119

BOTTOM
CHORD

<DETAIL AI

DETAIL C

Page 131

o = CROSS- MEMBER LOCATION

0

8 COEFG H J K L

LONGITUDINAL SECTIONS

Figure 3. Configuration of Cross Members in a Typical Ramp Bay

FOLDED BRIDGE

\
166.0·--...

TRAILER __ ____,

Figure 4. LV /FB in the Travel Mode

120

Page 260

WIND LOADS APPUED TO THE DECK
0.261 kip

0.163 kip

0

0 J I I
STATICALLY EQUIVALENT FORCES AND MOMENT
APPUED AT CENTROIDAL AXIS

LOCATION OF
MAXIYUK

~TOP CHORD u NOIUW. STRESS

0

0.261 kip

1.4 71 kip-inch

Fiaure C.3. 'find Loads Applied to the Cross Section of the Analytical Model

249

0

0

0

0

Page 261

MLC 7 VEHICLE POSITION

89" I 48" I • • • • 120" l83" ·I

Q
440"

FREE BODY DIAGRAM

3.939 lc

7.679 k-in 11.82 k-in 11.82 k-in
0.0806 k

AXIAL FORCE DIAGRAM

-1.313 k

-2.626 k

-3.939 k

MOMENT DIAGRAM 13.03 k-in
9.?48 k-in

1.345 k-in

1.206 "-in

-6.336 k-in

Figure C.4. Application of Braking Load to the Analytical Wodel

250

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