Dynamics of Structure and Foundation - A Unified Approach 2. Applications

Preface

1 Dynamic soil structure interaction

• 1.1 Introduction
• 1.1.1 The marriage of soil and structure
• 1.1.2 What does the interaction mean?
• 1.1.3 It is an expensive analysis do we need to do it?
• 1.1.4 Different soil models and their coupling to superstructure
• 1.2 Mathematical modeling of soil & structure
• 1.2.1 Lagrangian formulation for 2D frames or stick-models
• 1.2.2 What happens if the raft is flexible?
• 1.3 A generalised model for dynamic soil structure interaction
• 1.3.1 Dynamic response of a structure with multi degree of freedom considering the underlying
• soil stiffness
• 1.3.2 Extension of the above theory to system with multi degree of freedom
• 1.3.3 Estimation of damping ratio for the soil structure system
• 1.3.4 Formulation of damping ratio for single degree of freedom
• 1.3.5 Extension of the above theory to systems with multi-degree freedom
• 1.3.6 Some fallacies in coupling of soil and structure
• 1.3.7 What makes the structural response attenuate or amplify?
• 1.4 The art of modelling
• 1.4.1 Some modelling techniques
• 1.4.2 To sum it up
• 1.5 Geotechnical considerations for dynamic soil structure interaction
• 1.5.1 What parameters do I look for in the soil report?
• 1.6 Field tests
• 1.6.1 Block vibration test
• 1.6.2 Seismic cross hole test
• 1.6.3 How do I co-relate dynamic shear modulus when I do not have data from the dynamic
• soil tests?
• 1.7 Theoretical co-relation from other soil parameters
• 1.7.1 Co-relation for sandy and gravelly soil
• 1.7.2 Co-relation for saturated clay
• 1.8 Estimation of material damping of soil
• 1.8.1 Whitman’s formula
• 1.8.2 Hardin’ formula
• 1.8.3 Ishibashi and Zhang’s formula
• 1.9 All things said and done how do we estimate the strain in soil, specially if the strain is large?
• 1.9.1 Estimation of strain in soil for machine foundation
• 1.9.2 Estimation of soil strain for earthquake analysis
• 1.9.3 What do we do if the soil is layered with varying soil property?
• 1.9.4 Checklist of parameters to be looked in the soil reports
• 1.10 Epilogue

2. Analysis and design of machine foundations

• 2.1 Introduction
• 2.1.1 Case history #1
• 2.1.2 Case history #2
• 2.2 Different types of foundations
• 2.2.1 Block foundations resting on soil/piles
• 2.2.2 How does a block foundation supporting rotating machines differ from a normal
• foundation?
• 2.2.3 Foundation for centrifugal or rotary type of machine: Different theoretical methods
• for analysis of block foundation
• 2.2.4 Analytical methods
• 2.2.5 Approximate analysis to de-couple equations with non-proportional damping
• 2.2.6 Alternative formulation of coupled equation of motion for sliding and rocking mode
• 2.3 Trick to by pass damping – Magnification factor, the key to the problem
• 2.4 Effect of embedment on foundation
• 2.4.1 Novak and Beredugo’s model
• 2.4.2 Wolf’s model
• 2.5 Foundation supported on piles
• 2.5.1 Pile and soil modelled as finite element
• 2.5.2 Piles modelled as beams supported on elastic springs
• 2.5.3 Novak’s (1974) model for equivalent spring stiffness for piles 1
• 2.5.4 Equivalent pile springs in vertical direction
• 2.5.5 The group effect on the vertical spring and damping value of the piles
• 2.5.6 Effect of pile cap on the spring and damping stiffness
• 2.5.7 Equivalent pile springs and damping in the horizontal direction
• 2.5.8 Equivalent pile springs and damping in rocking motion
• 2.5.9 Group effect for rotational motion
• 2.5.10 Model for dynamic response of pile
• 2.5.11 Dynamic analysis of laterally loaded piles
• 2.5.12 Partially embedded piles under rocking mode
• 2.5.13 Group effect of pile
• 2.5.14 Comparison of results
• 2.5.15 Practical aspects of design of machine foundations
• 2.6 Special provisions of IS-code
• 2.6.1 Recommendations on vibration isolation
• 2.6.2 Frequency separation
• 2.6.3 Permissible amplitudes
• 2.6.4 Permissible stresses
• 2.6.5 Concrete and its placing
• 2.6.6 Reinforcements
• 2.6.7 Cover to concrete
• 2.7 Analysis and design of machine foundation under impact loading
• 2.7.1 Introduction
• 2.7.2 Mathematical model of a hammer foundation
• 2.8 Design of hammer foundation
• 2.8.1 Design criteria for hammer foundation
• 2.8.2 Discussion on the IS-code method of analysis
• 2.8.3 Check list for analysis of hammer foundation
• 2.8.4 Other techniques of analysis of Hammer foundation
• 2.9 Design of eccentrically loaded hammer foundation
• 2.9.1 Mathematical formulation of anvil placed eccentrically on a foundation
• 2.9.2 Damped equation of motion with eccentric anvil
• 2.10 Details of design
• 2.10.1 Reinforcement detailing
• 2.10.2 Construction procedure
• 2.11 Vibration measuring instruments
• 2.11.1 Some background on vibration measuring instruments and their application
• 2.11.2 Response due to motion of the support
• 2.11.3 Vibration pick-ups
• 2.12 Evaluation of friction damping from energy consideration
• 2.13 Vibration isolation
• 2.13.1 Active isolation
• 2.13.2 Passive isolation
• 2.13.3 Isolation by trench
• 2.14 Machine foundation supported on frames
• 2.14.1 Introduction
• 2.14.2 Different types of turbines and the generation process
• 2.14.3 Layout planning
• 2.14.4 Vibration analysis of turbine foundations
• 2.15 Dynamic soil-structure interaction model for vibration analysis of turbine foundation
• 2.16 Computer analysis of turbine foundation based on multi degree of freedom
• 2.17 Analysis of turbine foundation
• 2.17.1 The analysis
• 2.17.2 Calculation of the eigen values
• 2.17.3 So the ground rule is
• 2.17.4 Calculation of amplitude
• 2.17.5 Calculation of moments, shears and torsion
• 2.17.6 Practical aspects of design of Turbine foundation
• 2.18 Design of turbine foundation
• 2.18.1 Check list for turbine foundation design
• 2.18.2 Spring mounted turbine foundation

3. Analytical and design concepts for earthquake engineering

• 3.1 Introduction
• 3.1.1 Why do earthquakes happen in nature?
• 3.1.2 Essential difference between systems subjected to earthquake and vibration from machine
• 3.1.3 Some history of major earthquakes around the world
• 3.1.4 Intensity
• 3.1.5 Effect of earthquake on soil-foundation system
• 3.1.6 Liquefaction analysis
• 3.2 Earthquake analysis
• 3.2.1 Seismic coefficient method
• 3.2.2 Response spectrum method
• 3.2.3 Dynamic analysis under earthquake loading
• 3.2.4 How do we evaluate the earthquake force?
• 3.2.5 Earthquake analysis of systems with multidegree of freedom
• 3.2.6 Modal combination of forces
• 3.3 Time history analysis under earthquake force
• 3.3.1 Earthquake analysis of tall chimneys and stack like structure
• 3.4 Analysis of concrete dams
• 3.4.1 Earthquake analysis of concrete dam
• 3.4.2 A method for dynamic analysis of concrete dam
• 3.5 Analysis of earth dams and embankments
• 3.5.1 Dynamic earthquake analysis of earth dams
• 3.5.2 Mononobe’s method for analysis of earth dam
• 3.5.3 Gazetas’ method for earth dam analysis
• 3.5.4 Makadisi and Seed’s method for analysis of earth dam
• 3.5.5 Calculation of seismic force in dam and its stability
• 3.6 Analysis of earth retaining structures
• 3.6.1 Earthquake analysis of earth retaining structures
• 3.6.2 Mononobe’s method of analysis of retaining wall
• 3.6.3 Seed and Whitman’s method
• 3.6.4 Arango’s method
• 3.6.5 Steedman and Zeng’s method
• 3.6.6 Dynamic analysis of RCC retaining wall
• 3.6.7 Dynamic analysis of cantilever and counterfort retaining wall
• 3.6.8 Some discussions on the above method
• 3.6.9 Extension to the generic case of soil at a slope i behind the wall
• 3.6.10 Dynamic analysis of counterfort retaining wall
• 3.6.11 Soil sloped at an angle i with horizontal
• 3.7 Unyielding earth retaining structures
• 3.7.1 Earthquake Analysis of rigid walls when the soil does not yield
• 3.7.2 Ostadan’s method
• 3.8 Earthquake analysis of water tanks
• 3.8.1 Analysis of water tanks under earthquake force
• 3.8.2 Impulsive time period for non rigid walls
• 3.8.3 Sloshing time period of the vibrating fluid
• 3.8.4 Calculation of horizontal seismic force for tank resting on ground
• 3.8.5 Calculation of base shear for tanks resting on ground
• 3.8.6 Calculation of bending moment on the tank wall resting on the ground
• 3.8.7 Calculation of hydrodynamic pressure
• 3.9 Mathematical model for overhead tanks under earthquake
• 3.9.1 Earthquake Analysis for overhead tanks
• 3.9.2 Hydrodynamic pressure on tank wall and base
• 3.9.3 Hydrodynamic pressure for circular tank
• 3.9.4 Hydrodynamic pressure for rectangular tank
• 3.9.5 Effect of vertical ground acceleration
• 3.9.6 Pressure due to inertia of the wall
• 3.9.7 Maximum design dynamic pressure
• 3.10 Practical aspects of earthquake engineering
• 3.10.1 Epilogue

References

Subject index

Biography

Indrajit Chowdhury, Shambhu P. Dasgupta