Dynamic Analysis of Non-Linear Structures by the Method of Statistical Quadratization

1. Front Matter

   Pages N2-VII

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2. Introduction

   • M. G. Donley, P. D. Spanos

   Pages 1-13

3. Equivalent Stochastic Quadratization for Single-Degree-of-Freedom Systems

   • M. G. Donley, P. D. Spanos

   Pages 14-40

4. Equivalent Stochastic Quadratization for Multi-Degree-of-Freedom Systems

   • M. G. Donley, P. D. Spanos

   Pages 41-57

5. Potential Wave Forces on a Moored Vertical Cylinder

   • M. G. Donley, P. D. Spanos

   Pages 58-94

6. Equivalent Stochastic Quadratization for Tension Leg Platform Response to Viscous Drift Forces

   • M. G. Donley, P. D. Spanos

   Pages 95-114

7. Stochastic Response of a Tension Leg Platform to Viscous and Potential Drift Forces

   • M. G. Donley, P. D. Spanos

   Pages 115-146

8. Summary and Conclusions

   • M. G. Donley, P. D. Spanos

   Pages 147-150

9. Back Matter

   Pages 151-177

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1. 1 Introduction As offshore oil production moves into deeper water, compliant structural systems are becoming increasingly important. Examples of this type of structure are tension leg platfonns (TLP's), guyed tower platfonns, compliant tower platfonns, and floating production systems. The common feature of these systems, which distinguishes them from conventional jacket platfonns, is that dynamic amplification is minimized by designing the surge and sway natural frequencies to be lower than the predominant frequencies of the wave spectrum. Conventional jacket platfonns, on the other hand, are designed to have high stiffness so that the natural frequencies are higher than the wave frequencies. At deeper water depths, however, it becomes uneconomical to build a platfonn with high enough stiffness. Thus, the switch is made to the other side of the wave spectrum. The low natural frequency of a compliant platfonn is achieved by designing systems which inherently have low stiffness. Consequently, the maximum horizontal excursions of these systems can be quite large. The low natural frequency characteristic of compliant systems creates new analytical challenges for engineers. This is because geometric stiffness and hydrodynamic force nonlinearities can cause significant resonance responses in the surge and sway modes, even though the natural frequencies of these modes are outside the wave spectrum frequencies. High frequency resonance responses in other modes, such as the pitch mode of a TLP, are also possible.

• Fundament
• Mann
• calculus
• linear optimization
• linearity
• model
• offshore engineering
• simulation
• structure
• vibration

• Structural Dynamics Research Corporation, Milford, USA

  M. G. Donley

• Brown School of Engineering, Rice University, Houston, USA

  P. D. Spanos

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