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Informationen zum Autor Dr Helmut Wenzel , Managing Director Dieter Pichler , both of VCE Holding GmbH, Vienna, Austria Klappentext The development of methods for the monitoring and assessment of structures has been driven by the demand for better as well as cheaper methods. Constraints like undisturbed traffic flow, limited access possibilities and finally limited or even shrinking budgets have led to a development of an assessment model well fitted to the construction sector. Ambient vibration monitoring, which provides the opportunity to obtain useful data under ambient conditions for the assessment of structures and components, is the backbone of structural assessment monitoring and control. Nevertheless there is little available on this subject for the practising engineer. This book enables the practising engineer to learn about this fascinating area and gain information on practical applications. Ambient Vibration Monitoring describes current ambient vibration methodologies along with direct information on applicable solutions, and includes: Years of pioneering practical research collated into one book. Real-world applications with practical solutions. This book will be of interest to all engineers engaged in structural assessment monitoring and control, and provides a useful tool for students of structural dynamics, civil engineering, mechanical engineering and related fields. Zusammenfassung Written by a widely respected authority in this area! Ambient Vibration Monitoring describes the current practice of ambient vibration methodologies illustrated by a number of practical examples. Inhaltsverzeichnis PREFACE xi ACKNOWLEDGEMENTS xiii SUMMARY xv 1 INTRODUCTION 1 1.1 Scope of Applications 1 1.2 Laws and Regulations 2 1.3 Theories on the Development of the AVM 4 2 OBJECTIVES OF APPLICATIONS 7 2.1 System Identification 7 2.1.1 Eigenfrequencies and Mode Shapes 8 2.1.2 Damping 11 2.1.3 Deformations and Displacements 11 2.1.4 Vibration Intensity 12 2.1.5 Trend Cards 13 2.2 Stress Test 13 2.2.1 Determination of Static and Dynamic Stresses 14 2.2.2 Determination of the Vibration Elements 14 2.2.3 Stress of Individual Structural Members 15 2.2.4 Determination of Forces in Tendons and Cables 15 2.3 Assessment of Stresses 17 2.3.1 Structural Safety 17 2.3.2 Structural Member Safety 19 2.3.3 Maintenance Requirements and Intervals 19 2.3.4 Remaining Operational Lifetime 21 2.4 Load Observation (Determination of External Influences) 21 2.4.1 Load Collective 21 2.4.2 Stress Characteristic 21 2.4.3 Verification of Load Models 23 2.4.4 Determination of Environmental Influences 24 2.4.5 Determination of Specific Measures 24 2.4.6 Check on the Success of Rehabilitation Measures 25 2.4.7 Dynamic Effects on Cables and Tendons 25 2.4.8 Parametric Excitation 27 2.5 Monitoring of the Condition of Structures 28 2.5.1 Assessment of Individual Objects 29 2.5.2 Periodic Monitoring 31 2.5.3 BRIMOS_ Recorder 31 2.5.4 Permanent Monitoring 34 2.5.5 Subsequent Measures 35 2.6 Application of Ambient Vibration Testing to Structures for Railways 35 2.6.1 Sleepers 36 2.6.2 Noise and Vibration Problems 39 2.7 Limitations 49 2.7.1 Limits of Measuring Technology 49 2.7.2 Limits of Application 51 2.7.3 Limits of Analysis 52 2.7.4 Perspectives 53 References 54 3 FEEDBACK FROM MONITORING TO BRIDGE DESIGN 55 3.1 Economic Background 55 3.2 Lessons Learned 56 3.2.1 Conservative Design 56 3.2.2 External versus Internal Pre-stressing 57 3.2.3 Influence of Temperature 57 <...
