Structural Vibration Analysis, Design and Troubleshooting

Instructors

C. (Raj) Sundararajan, Ph.D., MASCE
Dr. Sundararajan has over 30 years of experience in the analysis and design of structures subjected to dynamic forces. He is President of EDA Consultants (formerly known as "Engineering Dynamics Associates").Previously he held senior technical positions at Lummus Company, Foster Wheeler Corporation and Impell Corporation.

He has published two books and over 50 technical papers, and authored numerous technical reports. He received ASME Best Paper Award in 1986. He has taught short courses for practicing engineers during the past 20 years. He has a B.E. in Civil Engineering from University of Madras, India, an M.E. in Civil Engineering from Indian Institute of Science, and a Ph.D. in Civil Engineering from University of Waterloo, Canada.

Course Description

Accidental, environmental and operational dynamic forces due to wind, earthquakes, waves, machinery operations, explosions and impact are major causes of structural failures. Equivalent static loads were used to design for dynamic loads in the past because of the computational complexities of dynamic analysis. With the availability of abundant computer resources (powerful PCs), dynamic analysis is more widely used nowadays. Structural designs on the basis of dynamic analyses are usually less conservative and thus more economical compared to equivalent static design procedures. This shore course will teach how to compute the structural response to dynamic loads and design for these loads.

The course will be divided into 5 parts: (1) Structural vibration fundamentals, (2) Analysis techniques, (3) Synthesis of analysis and test results, (4) Designing for dynamic forces, and (5) Special topics such as fluid-structure interaction, flow-induced vibrations, soil-structure interaction and foundation design for vibratory forces.

Emphasis of the course is not on derivation of equations but on assumptions and limitations of various analysis techniques, and guidelines on when to use which method. Example problems and case studies will be presented as necessary. participants will have ample opportunity to interact with the instructor and discuss their problems.

Seminar Benefits

• Learn how to compute natural frequencies of simple and complex structures
• Learn how to compute structural response to dynamic forces due to earthquakes, blasts, winds, waves, human activities and machinery operations
• Understand the underlying assumptions, approximations and limitations of different methods and thus choose the most appropriate method of analysis
• Compare analysis results with test results or field data and fine-tune analysis models
• Learn a variety of strategies of reducing vibrations of new and existing structures: frequency separation techniques, dampening, vibration absorbers (tuned mass dampers), vibration isolation, etc.
• Learn how to analyze and design rotating machinery foundations
• Gain exposure to special topics such as solid-fluid systems, flow induced vibrations and random vibrations
• Opportunity to discuss your projects with the instructor

Learning Objectives

This is an intermediate level course. Learn how to compute the natural frequencies, mode shapes and forced-vibration response of structures and structural components. Benchmarking analytical results with test results or field data is also taught. A variety of methods for reducing excessive vibrations are discussed. On completion of the course, you will know how to identify potential vibration problems during the design stage and design against them economically.

Who Should Attend?

Structural engineers and engineering supervisors who are responsible for designing or qualifying structures and structural components subjected to dynamic forces and those responsible for auditing reviewing, or approving such tasks will benefit from the course. Those with very little experience in vibration analysis as well as those with some years of experience will find the course useful. This is an intermediate level course.

Summary Outline

Day One:

• Structural vibration fundamentals
  • Free vibration and forced vibration
  • Analysis models for structural dynamic systems
  • Types of damping
  • Types of dynamic forces
  • Representation of dynamic forces in the time and frequency domains
• Analysis Techniques
  • One-degree-of-freedom systems
    • Natural frequency and critical damping
    • Harmonic forces and the concept of resonance
    • Transient and impulse forces
    • Dynamic amplification factor Transfer function and transmissibility Shock spectra and response spectra
  • Multiple-degrees-of-freedom systems
    • Natural frequencies and mode shapes
    • Direct time-history analysis
    • Model time-history analysis
    • Response spectrum analysis

Day Two:

• Continuous systems
  • Lateral vibration of beams
  • Lateral vibration of plates
  • Exact and approximate solutions
• Practical aspects of finite element modeling and analysis of vibration problems
  • This is not a course on finite element analysis. Course concentrates on the special aspects of modeling and analyzing complex structures for vibration analysis. Advantages and disadvantages of different methods of analysis such as coupled and decoupled analysis, and time-domain analysis and frequency-domain analysis are discussed with guidelines on which methods are best suited for what types of problems. Guidelines for mesh size, cut-off frequency and incremental time-steps are also presented.
• Structural response to blast loads
  • Blast load computation
  • Dynamic response analysis
• Structural response to earthquakes and underground explosions
  • Representation of base excitation
  • Time-history analysis
  • Response spectrum analysis
  • Design considerations
• Modal testing
  • Test procedure
  • Interpretation of test data
  • Determination of natural frequencies, mode shapes and damping
• Synthesis of analysis and test results
  • Test-analysis correlation
  • Fine-tuning finite element models using test data
• Vibration Absorbers (tuned mass dampers)
  • Basic concept, types of absorbers and design procedure
• Vibration Isolation
  • Basic concepts, Types of isolators and design procedure

Day Three:

• Designing for dynamic forces
  • Design aspects are discussed throughout the course. Here the different strategies of reducing vibration are summarized and relative merits discussed with practical examples.
• Special Topics
  • Basic concepts and overview of the following special topics are presented.
    • Foundation design for vibratory forces
    • Fluid-structure systems
    • Flow-induced vibrations
      • Random vibration analysis