Civil Engineering Association

Ghazvin - Rashat - Anzaliy Railway Bridge DESIGN OF LEAD RUBBER BEARINGS STRUCTURAL CALCULATIONS

TABLE OF CONTENTS
1. SUMMARY OF CALCULATIONS........................................................................................... 4
1.1 CHANGES IN REVISION ................................................................................................... 4
1.2 EFFECT OF INCREASED RUBBER SHEAR MODULUS...................................................................... 4
1.2.1 ISOLATION SYSTEM DISPLACEMENTS AND FORCES............................................................. 4
1.2.2 DYNAMIC PROPERTIES AND DAMPING ........................................................................... 5
1.2.3 TEST CONDITIONS.................................................................................................. 5
2. PROJECT REQUIREMENTS ................................................................................................... 7
2.1 REFERENCES................................................................................................................. 7
2.2 DESIGN CONDITIONS..................................................................................................... 7
3. PROCEDURES USED FOR BEARING DESIGN.......................................................................... 9
3.1 DEFINITIONS ................................................................................................................ 9
3.2 CALCULATION OF EQUIVALENT SHEAR STRAINS ..................................................................... 10
3.3 LIMITING STRAIN CRITERIA............................................................................................... 11
3.3.1 AASHTO LIMITING STRAIN CRITERIA........................................................................... 11
3.4 VERTICAL LOAD STABILITY ................................................................................................ 11
3.4.1 AASHTO VERTICAL LOAD STABILITY ............................................................................ 11
3.5 AASHTO LATERAL RESTORING FORCE ................................................................................ 13
3.6 LATERAL STIFFNESS PARAMETERS FOR BEARING....................................................................... 13
3.7 SYSTEM PROPERTY MODIFICATION FACTORS......................................................................... 15
3.7.1 AGE CHANGE IN PROPERTIES ................................................................................... 16
3.7.2 TEMPERATURE CHANGE IN PROPERTIES......................................................................... 17
3.7.3 MODIFICATION FACTORS USED FOR DESIGN................................................................. 17
4. BEARING DESIGN CALCULATIONS.................................................................................... 19
4.1 ANALYSIS RESULTS USED FOR ISOLATION SYSTEM DESIGN......................................................... 19
4.2 DESIGN LOADS ........................................................................................................... 20
4.3 MATERIAL PROPERTIES .................................................................................................... 20
4.4 BEARING SHAPE .......................................................................................................... 20
4.5 BEARING DIMENSIONS.................................................................................................. 21
4.6 BEARING PROPERTIES..................................................................................................... 22
4.7 LIMITING STRAIN CALCULATIONS ...................................................................................... 23
4.7.1 AASHTO CRITERIA ............................................................................................... 23
4.7.1.1 AASHTO Equation 25 ............................................................................................................. 23
4.7.1.2 AASHTO Equation 26 ............................................................................................................. 24
4.7.1.3 AASHTO Equation 27 ............................................................................................................. 24
4.8 VERTICAL LOAD STABILITY ................................................................................................ 25
4.8.1 AASHTO REQUIREMENTS ....................................................................................... 25
4.9 RESTORING FORCE....................................................................................................... 26
4.10 EFFECTIVE STIFFNESS AND DAMPING .............................................................................. 27

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